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Song X, Luo S, Fan X, Tang M, Zhao X, Chen W, Yang Q, Quan Z. Controlled Synthesis of PtNi Hexapods for Enhanced Oxygen Reduction Reaction. Front Chem 2018; 6:468. [PMID: 30338256 PMCID: PMC6180145 DOI: 10.3389/fchem.2018.00468] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2018] [Accepted: 09/18/2018] [Indexed: 11/13/2022] Open
Abstract
Well-defined PtNi nanocrystals represent one of the most efficient electrocatalysts to boost the oxygen reduction reaction (ORR), especially in the shape of octahedrons, nanoframes, and nanowires. However, the synthesis of complex PtNi nanostructure is still a great challenge. Herein, we report a new class of PtNi hexapods with high activity and stability toward ORR. The hexapods are prepared by selective capping and simultaneous corrosion. By controlling the oxidative etching, PtNi polyhedrons and nanoparticles are obtained, respectively. The intriguing hexapods are composed of six nanopods with an average length of 12.5 nm. Due to their sharp tips and three-dimensional (3D) accessible surfaces, the PtNi hexapods show a high mass activity of 0.85 A mg Pt - 1 at 0.9 V vs. RHE, which are 5.4-fold higher than commercial Pt/C, also outperforming PtNi polyhedrons and PtNi nanoparticles. In addition, the mass activity of PtNi hexapods maintains 92.3% even after 10,000 potential cycles.
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Affiliation(s)
- Xing Song
- Department of Chemistry, Southern University of Science and Technology (SUSTech), Shenzhen, China
| | - Shuiping Luo
- Department of Chemistry, Southern University of Science and Technology (SUSTech), Shenzhen, China
| | - Xiaokun Fan
- Department of Chemistry, Southern University of Science and Technology (SUSTech), Shenzhen, China
| | - Min Tang
- Department of Chemistry, Southern University of Science and Technology (SUSTech), Shenzhen, China
| | - Xixia Zhao
- Department of Chemistry, Southern University of Science and Technology (SUSTech), Shenzhen, China
| | - Wen Chen
- Department of Chemistry, Southern University of Science and Technology (SUSTech), Shenzhen, China
| | - Qi Yang
- Department of Chemistry, Southern University of Science and Technology (SUSTech), Shenzhen, China
| | - Zewei Quan
- Department of Chemistry, Southern University of Science and Technology (SUSTech), Shenzhen, China
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153
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Itasaka H, Mimura KI, Kato K. Extra Surfactant-Assisted Self-Assembly of Highly Ordered Monolayers of BaTiO₃ Nanocubes at the Air⁻Water Interface. Nanomaterials (Basel) 2018; 8:E739. [PMID: 30231568 DOI: 10.3390/nano8090739] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/22/2018] [Revised: 09/13/2018] [Accepted: 09/14/2018] [Indexed: 11/16/2022]
Abstract
Assembly of nanocrystals into ordered two- or three-dimensional arrays is an essential technology to achieve their application in novel functional devices. Among a variety of assembly techniques, evaporation-induced self-assembly (EISA) is one of the prospective approaches because of its simplicity. Although EISA has shown its potential to form highly ordered nanocrystal arrays, the formation of uniform nanocrystal arrays over large areas remains a challenging subject. Here, we introduce a new EISA method and demonstrate the formation of large-scale highly ordered monolayers of barium titanate (BaTiO₃, BT) nanocubes at the air-water interface. In our method, the addition of an extra surfactant to a water surface assists the EISA of BT nanocubes with a size of 15⁻20 nm into a highly ordered arrangement. We reveal that the compression pressure exerted by the extra surfactant on BT nanocubes during the solvent evaporation is a key factor in the self-assembly in our method. The BT nanocube monolayers transferred to substrates have sizes up to the millimeter scale and a high out-of-plane crystal orientation, containing almost no microcracks and voids.
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154
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Khan J, Bashir S, Khan MA, Mohammad MA, Isreb M. Fabrication and characterization of dexibuprofen nanocrystals using microchannel fluidic rector. Drug Des Devel Ther 2018; 12:2617-2626. [PMID: 30214150 PMCID: PMC6120565 DOI: 10.2147/dddt.s168522] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Purpose Dexibuprofen is an enantiomer of ibuprofen with low bioavailability which results from its hydrophobic nature. Nanosuspensions have developed a podium to solve the in vitro dissolution problem that frequently occurs in current research. Materials and methods The drug and polymer solutions were mixed in a microchannel fluid reactor and the successive embryonic nanosuspension was decanted into a vial having the polymer solution. The impact of different process and formulation parameters including inlet angle, antisolvent and solvent flow rate(s), mixing time, drug concentration, polymer type and concentration was evaluated. Results and discussion Stable dexibuprofen nanocrystals with a particle size of 45±3.0 nm and polydispersity index of 0.19±0.06 were obtained. Differential scanning calorimetry and powder X-ray diffraction confirmed the crystallinity. The key parameters observed were inlet angle 10°, antisolvent to solvent volume of 2.0/0.5 mL/min, 60 minutes mixing with 5 minutes sonication, Poloxamer-407 with a concentration of 0.5% w/v and drug concentration (5 mg/mm). The 60-day stability studies revealed that the nanocrystals were stable at 4°C and 25°C. The scanning electron microscopy and transmission electron microscopy images showed crystalline morphology with a homogeneous distribution. Conclusion Stable dexibuprofen nanocrystals with retentive distinctive characteristics and having marked dissolution rate compared to raw and marketed formulations were efficiently fabricated. In future perspectives, these nanocrystals could be converted to solid dosage form and the process can be industrialized by chemical engineering approach.
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Affiliation(s)
- Jahangir Khan
- Department of Pharmacy, Faculty of Pharmacy, University of Sargodha, Sargodha, Pakistan, .,Department of Pharmacy, University of Malakand, Dīr, Khyber Pakhtunkhwa, Pakistan, .,School of Pharmacy, Institute of Life Science Research, School of Pharmacy, University of Bradford, Bradford, UK,
| | - Sajid Bashir
- Department of Pharmacy, Faculty of Pharmacy, University of Sargodha, Sargodha, Pakistan,
| | | | - Mohammad Amin Mohammad
- School of Pharmacy, Institute of Life Science Research, School of Pharmacy, University of Bradford, Bradford, UK,
| | - Mohammad Isreb
- School of Pharmacy, Institute of Life Science Research, School of Pharmacy, University of Bradford, Bradford, UK,
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155
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Kravchyk KV, Piveteau L, Caputo R, He M, Stadie NP, Bodnarchuk MI, Lechner RT, Kovalenko MV. Colloidal Bismuth Nanocrystals as a Model Anode Material for Rechargeable Mg-Ion Batteries: Atomistic and Mesoscale Insights. ACS Nano 2018; 12:8297-8307. [PMID: 30086624 DOI: 10.1021/acsnano.8b03572] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
At present, the technical progress of secondary batteries employing metallic magnesium as the anode material has been severely hindered due to the low oxidation stability of state-of-the-art Mg electrolytes, which cannot be used to explore high-voltage (>3 V versus Mg2+/Mg) cathode materials. All known electrolytes based on oxidatively stable solvents and salts, such as Mg(ClO4)2 and Mg bis(trifluoromethanesulfonimide), react with the metallic magnesium anode, forming a passivating layer at its surface and preventing the reversible plating and stripping of Mg. Therefore, in a near-term effort to extend the upper voltage limit in the exploration of future candidate Mg-ion battery cathode materials, bismuth anodes have attracted considerable attention due to their efficient magnesiation and demagnesiation alloying reaction in such electrolytes. In this context, we present colloidal Bi nanocrystals (NCs) as a model anode material for the exploration of cathode materials for rechargeable Mg-ion batteries. Bi NCs demonstrate a stable capacity of 325 mAh g-1 over at least 150 cycles at a current density of 770 mA g-1, which is among the most-stable performance of Mg-ion battery anode materials. First-principles crystal structure prediction methodologies and ex situ X-ray diffraction measurements reveal that the magnesiation of Bi NCs leads to the simultaneous formation of the low-temperature trigonal structure, α-Mg3Bi2, and the high-temperature cubic structure, β-Mg3Bi2, which sheds insight into the high stability of this reversible alloying reaction. Furthermore, small-angle X-ray scattering measurements indicate that although the monodispersed, crystalline nature of the Bi NCs is indeed disturbed during the first discharge step, no notable morphological or structural changes occur in the following electrochemical cycles. The cost-effective and facile synthesis of colloidal Bi NCs and their remarkably high electrochemical stability upon magnesiation make them an excellent model anode material with which to accelerate progress in the field of Mg-ion secondary batteries.
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Affiliation(s)
- Kostiantyn V Kravchyk
- Department of Chemistry and Applied Biosciences , ETH Zürich , Vladimir-Prelog-Weg 1 , Zurich , CH-8093 Switzerland
- Empa-Swiss Federal Laboratories for Materials Science and Technology , Überlandstrasse 129 , Dübendorf , CH-8600 Switzerland
| | - Laura Piveteau
- Department of Chemistry and Applied Biosciences , ETH Zürich , Vladimir-Prelog-Weg 1 , Zurich , CH-8093 Switzerland
- Empa-Swiss Federal Laboratories for Materials Science and Technology , Überlandstrasse 129 , Dübendorf , CH-8600 Switzerland
| | - Riccarda Caputo
- Department of Chemistry and Applied Biosciences , ETH Zürich , Vladimir-Prelog-Weg 1 , Zurich , CH-8093 Switzerland
| | - Meng He
- Department of Chemistry and Applied Biosciences , ETH Zürich , Vladimir-Prelog-Weg 1 , Zurich , CH-8093 Switzerland
- Empa-Swiss Federal Laboratories for Materials Science and Technology , Überlandstrasse 129 , Dübendorf , CH-8600 Switzerland
| | - Nicholas P Stadie
- Department of Chemistry and Applied Biosciences , ETH Zürich , Vladimir-Prelog-Weg 1 , Zurich , CH-8093 Switzerland
- Empa-Swiss Federal Laboratories for Materials Science and Technology , Überlandstrasse 129 , Dübendorf , CH-8600 Switzerland
| | - Maryna I Bodnarchuk
- Empa-Swiss Federal Laboratories for Materials Science and Technology , Überlandstrasse 129 , Dübendorf , CH-8600 Switzerland
| | - Rainer T Lechner
- Institute of Physics , Montanuniversitaet Leoben , Franz-Josef-Strasse 18 , A-8700 Leoben , Austria
| | - Maksym V Kovalenko
- Department of Chemistry and Applied Biosciences , ETH Zürich , Vladimir-Prelog-Weg 1 , Zurich , CH-8093 Switzerland
- Empa-Swiss Federal Laboratories for Materials Science and Technology , Überlandstrasse 129 , Dübendorf , CH-8600 Switzerland
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156
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Gilmore RH, Winslow SW, Lee EMY, Ashner MN, Yager KG, Willard AP, Tisdale WA. Inverse Temperature Dependence of Charge Carrier Hopping in Quantum Dot Solids. ACS Nano 2018; 12:7741-7749. [PMID: 29927579 DOI: 10.1021/acsnano.8b01643] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
In semiconductors, increasing mobility with decreasing temperature is a signature of charge carrier transport through delocalized bands. Here, we show that this behavior can also occur in nanocrystal solids due to temperature-dependent structural transformations. Using a combination of broadband infrared transient absorption spectroscopy and numerical modeling, we investigate the temperature-dependent charge transport properties of well-ordered PbS quantum dot (QD) solids. Contrary to expectations, we observe that the QD-to-QD charge tunneling rate increases with decreasing temperature, while simultaneously exhibiting thermally activated nearest-neighbor hopping behavior. Using synchrotron grazing-incidence small-angle X-ray scattering, we show that this trend is driven by a temperature-dependent reduction in nearest-neighbor separation that is quantitatively consistent with the measured tunneling rate.
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Affiliation(s)
| | | | | | | | - Kevin G Yager
- Center for Functional Nanomaterials , Brookhaven National Laboratory , Upton , New York 11973 , United States
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157
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Lin H, Tian P, Luo C, Wang H, Zhang J, Yang J, Peng H. Luminescent Nanofluids of Organometal Halide Perovskite Nanocrystals in Silicone Oils with Ultrastability. ACS Appl Mater Interfaces 2018; 10:27244-27251. [PMID: 30036467 DOI: 10.1021/acsami.8b05489] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Luminescent nanofluids are successfully prepared by directly dispersing organometal halide perovskite nanocrystals (OHP NCs) with different emission colors in silicone oils. The photoluminescence quantum yields of nanofluids with green, blue and red emission are 47, 32, and 19%, respectively. Furthermore, the nanofluids greatly enhance the stability of OHP NCs and show excellent resistance against moisture, heat and ultraviolet light. The luminescent nanofluids can be used as liquid color converter for LED. By loading them onto silica aerogel, luminescent perovskite powders were achieved. Their applications as phosphor additives for preparing luminescent PMMA composites were demonstrated.
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Affiliation(s)
- Hechun Lin
- Key Laboratory of Polar Materials and Devices, Ministry of Education, Department of Electrical Engineering , East China Normal University , Shanghai , P. R. China
| | - Pei Tian
- Key Laboratory of Polar Materials and Devices, Ministry of Education, Department of Electrical Engineering , East China Normal University , Shanghai , P. R. China
| | - Chunhua Luo
- Key Laboratory of Polar Materials and Devices, Ministry of Education, Department of Electrical Engineering , East China Normal University , Shanghai , P. R. China
| | - Hai Wang
- Key Laboratory of Polar Materials and Devices, Ministry of Education, Department of Electrical Engineering , East China Normal University , Shanghai , P. R. China
| | - Jungang Zhang
- Shanghai Transcom Scientific Co., Ltd. , 528 Ruiqing Road, 20A, Z. J. East Area Hi-Tech Medical Park , Shanghai , P. R. China
| | - Jianping Yang
- Shanghai Transcom Scientific Co., Ltd. , 528 Ruiqing Road, 20A, Z. J. East Area Hi-Tech Medical Park , Shanghai , P. R. China
| | - Hui Peng
- Key Laboratory of Polar Materials and Devices, Ministry of Education, Department of Electrical Engineering , East China Normal University , Shanghai , P. R. China
- Collaborative Innovation Center of Extreme Optics , Shanxi University , Taiyuan , Shanxi 030006 , P. R. China
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158
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Mei X, Wu B, Guo X, Liu X, Rong Z, Liu S, Chen Y, Qin D, Xu W, Hou L, Chen B. Efficient CdTe Nanocrystal/TiO₂ Hetero-Junction Solar Cells with Open Circuit Voltage Breaking 0.8 V by Incorporating A Thin Layer of CdS Nanocrystal. Nanomaterials (Basel) 2018; 8:E614. [PMID: 30104543 PMCID: PMC6116231 DOI: 10.3390/nano8080614] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/22/2018] [Revised: 08/10/2018] [Accepted: 08/10/2018] [Indexed: 11/18/2022]
Abstract
Nanocrystal solar cells (NCs) allow for large scale solution processing under ambient conditions, permitting a promising approach for low-cost photovoltaic products. Although an up to 10% power conversion efficiency (PCE) has been realized with the development of device fabrication technologies, the open circuit voltage (Voc) of CdTe NC solar cells has stagnated below 0.7 V, which is significantly lower than most CdTe thin film solar cells fabricated by vacuum technology (around 0.8 V~0.9 V). To further improve the NC solar cells' performance, an enhancement in the Voc towards 0.8⁻1.0 V is urgently required. Given the unique processing technologies and physical properties in CdTe NC, the design of an optimized band alignment and improved junction quality are important issues to obtain efficient solar cells coupled with high Voc. In this work, an efficient method was developed to improve the performance and Voc of solution-processed CdTe nanocrystal/TiO₂ hetero-junction solar cells. A thin layer of solution-processed CdS NC film (~5 nm) as introduced into CdTe NC/TiO₂ to construct hetero-junction solar cells with an optimized band alignment and p-n junction quality, which resulted in a low dark current density and reduced carrier recombination. As a result, devices with improved performance (5.16% compared to 2.63% for the control device) and a Voc as high as 0.83 V were obtained; this Voc value is a record for a solution-processed CdTe NC solar cell.
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Affiliation(s)
- Xianglin Mei
- School of Materials Science and Engineering, South China University of Technology, Guangzhou 510640, China.
| | - Bin Wu
- School of Materials Science and Engineering, South China University of Technology, Guangzhou 510640, China.
| | - Xiuzhen Guo
- School of Materials Science and Engineering, South China University of Technology, Guangzhou 510640, China.
| | - Xiaolin Liu
- School of Materials Science and Engineering, South China University of Technology, Guangzhou 510640, China.
| | - Zhitao Rong
- School of Materials Science and Engineering, South China University of Technology, Guangzhou 510640, China.
| | - Songwei Liu
- School of Materials Science and Engineering, South China University of Technology, Guangzhou 510640, China.
| | - Yanru Chen
- School of Materials Science and Engineering, South China University of Technology, Guangzhou 510640, China.
| | - Donghuan Qin
- School of Materials Science and Engineering, South China University of Technology, Guangzhou 510640, China.
- Institute of Polymer Optoelectronic Materials & Devices, State Key Laboratory of Luminescent Materials & Devices, South China University of Technology, Guangzhou 510640, China.
| | - Wei Xu
- School of Materials Science and Engineering, South China University of Technology, Guangzhou 510640, China.
- Institute of Polymer Optoelectronic Materials & Devices, State Key Laboratory of Luminescent Materials & Devices, South China University of Technology, Guangzhou 510640, China.
| | - Lintao Hou
- Guangdong Provincial Key Laboratory of Optical Fiber Sensing and Communications, Guangzhou Key Laboratory of Vacuum Coating Technologies and New Energy Materials, Siyuan Laboratory, Department of Physics, Jinan University, Guangzhou 510632, China.
| | - Bingchang Chen
- School of Materials Science and Engineering, South China University of Technology, Guangzhou 510640, China.
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159
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Liu Y, Zhang Y, Lim KH, Ibáñez M, Ortega S, Li M, David J, Martí-Sánchez S, Ng KM, Arbiol J, Kovalenko MV, Cadavid D, Cabot A. High Thermoelectric Performance in Crystallographically Textured n-Type Bi 2Te 3- xSe x Produced from Asymmetric Colloidal Nanocrystals. ACS Nano 2018; 12:7174-7184. [PMID: 29966413 DOI: 10.1021/acsnano.8b03099] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
In the present work, we demonstrate crystallographically textured n-type Bi2Te3- xSe x nanomaterials with exceptional thermoelectric figures of merit produced by consolidating disk-shaped Bi2Te3- xSe x colloidal nanocrystals (NCs). Crystallographic texture was achieved by hot pressing the asymmetric NCs in the presence of an excess of tellurium. During the hot press, tellurium acted both as lubricant to facilitate the rotation of NCs lying close to normal to the pressure axis and as solvent to dissolve the NCs approximately aligned with the pressing direction, which afterward recrystallize with a preferential orientation. NC-based Bi2Te3- xSe x nanomaterials showed very high electrical conductivities associated with large charge carrier concentrations, n. We hypothesize that such large n resulted from the presence of an excess of tellurium during processing, which introduced a high density of donor TeBi antisites. Additionally, the presence in between grains of traces of elemental Te, a narrow band gap semiconductor with a work function well below Bi2Te3- xSe x, might further contribute to increase n through spillover of electrons, while at the same time blocking phonon propagation and hole transport through the nanomaterial. NC-based Bi2Te3- xSe x nanomaterials were characterized by very low thermal conductivities in the pressing direction, which resulted in ZT values up to 1.31 at 438 K in this direction. This corresponds to a ca. 40% ZT enhancement from commercial ingots. Additionally, high ZT values were extended over wider temperature ranges due to reduced bipolar contribution to the Seebeck coefficient and the thermal conductivity. Average ZT values up to 1.15 over a wide temperature range, 320 to 500 K, were measured, which corresponds to a ca. 50% increase over commercial materials in the same temperature range. Contrary to most previous works, highest ZT values were obtained in the pressing direction, corresponding to the c crystallographic axis, due to the predominance of the thermal conductivity reduction over the electrical conductivity difference when comparing the two crystal directions.
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Affiliation(s)
- Yu Liu
- Catalonia Energy Research Institute - IREC , Sant Adria de Besòs , 08930 Barcelona , Spain
| | - Yu Zhang
- Catalonia Energy Research Institute - IREC , Sant Adria de Besòs , 08930 Barcelona , Spain
| | - Khak Ho Lim
- Department of Chemical and Biological Engineering , Hong Kong University of Science and Technology , Hong Kong , China
| | - Maria Ibáñez
- Institute of Inorganic Chemistry, Department of Chemistry and Applied Biosciences , ETH Zürich , Vladimir Prelog Weg 1 , CH-8093 Zürich , Switzerland
- Empa-Swiss Federal Laboratories for Materials Science and Technology , Überlandstrasse 129 , CH-8600 Dübendorf , Switzerland
| | - Silvia Ortega
- Catalonia Energy Research Institute - IREC , Sant Adria de Besòs , 08930 Barcelona , Spain
| | - Mengyao Li
- Catalonia Energy Research Institute - IREC , Sant Adria de Besòs , 08930 Barcelona , Spain
| | - Jérémy David
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC, and BIST , Campus UAB , Bellaterra, 08193 Barcelona , Catalonia Spain
| | - Sara Martí-Sánchez
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC, and BIST , Campus UAB , Bellaterra, 08193 Barcelona , Catalonia Spain
| | - Ka Ming Ng
- Department of Chemical and Biological Engineering , Hong Kong University of Science and Technology , Hong Kong , China
| | - Jordi Arbiol
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC, and BIST , Campus UAB , Bellaterra, 08193 Barcelona , Catalonia Spain
- ICREA Pg. Lluis Companys 23 , 08010 Barcelona , Spain
| | - Maksym V Kovalenko
- Institute of Inorganic Chemistry, Department of Chemistry and Applied Biosciences , ETH Zürich , Vladimir Prelog Weg 1 , CH-8093 Zürich , Switzerland
- Empa-Swiss Federal Laboratories for Materials Science and Technology , Überlandstrasse 129 , CH-8600 Dübendorf , Switzerland
| | - Doris Cadavid
- Catalonia Energy Research Institute - IREC , Sant Adria de Besòs , 08930 Barcelona , Spain
- Departamento de Física , Universidad Nacional de Colombia , Ciudad Universitaria, 111321 Bogotá , Colombia
| | - Andreu Cabot
- Catalonia Energy Research Institute - IREC , Sant Adria de Besòs , 08930 Barcelona , Spain
- ICREA Pg. Lluis Companys 23 , 08010 Barcelona , Spain
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160
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Saeki R, Ohgai T. Effect of Growth Rate on the Crystal Orientation and Magnetization Performance of Cobalt Nanocrystal Arrays Electrodeposited from Aqueous Solution. Nanomaterials (Basel) 2018; 8:nano8080566. [PMID: 30042366 PMCID: PMC6116207 DOI: 10.3390/nano8080566] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/15/2018] [Revised: 07/15/2018] [Accepted: 07/19/2018] [Indexed: 11/16/2022]
Abstract
The formation work of a two-dimensional hcp-Co (metallic cobalt crystal with hexagonal close packed structure) nucleus, Whkl, was calculated by Pangarov's theory. W002 was estimated to be smaller than W100 in a cathode potential range nobler than the transition potential, Etra (ca. -0.77 V vs. Ag/AgCl). To confirm the above estimation, ferromagnetic nanocomposite thick films, which contained (002) textured hcp-Co nanocrystal arrays, were synthesized by potentiostatic electrochemical reduction of Co2+ ions in anodized aluminum oxide (AAO) nanochannel films with ca. 45 µm thickness. The aspect ratio of hcp-Co nanocrystals with a diameter of ca. 25 nm reached up to ca. 1800. Our experimental results revealed that the texture coefficient, TC002, increased when decreasing the overpotential for hcp-Co electrodeposition by shifting the cathode potential nobler than Etra. In a similar way, TC002 increased sharply by decreasing the growth rate of the hcp-Co nanocrystals so that it was smaller than the transition growth rate, Rtra (ca. 600 nm s-1). The perpendicular magnetization performance was observed in AAO nanocomposite films containing hcp-Co nanocrystal arrays. With increasing TC002, the coercivity of the nanocomposite film increased and reached up to 1.66 kOe, with a squareness of ca. 0.9 at room temperature.
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Affiliation(s)
- Ryusei Saeki
- Graduate School of Engineering, Nagasaki University, Bunkyo-machi 1-14, Nagasaki 852-8521, Japan.
| | - Takeshi Ohgai
- Faculty of Engineering, Nagasaki University, Bunkyo-machi 1-14, Nagasaki 852-8521, Japan.
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161
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Huo D, Xia Y. Quantifying the Sub-Cellular Distributions of Gold Nanospheres Taken Up by Cells through Stepwise, Site-Selective Etching. Chemistry 2018; 24:8513-8518. [PMID: 29637633 DOI: 10.1002/chem.201800525] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2018] [Indexed: 11/11/2022]
Abstract
A quantitative understanding of the sub-cellular distributions of nanospheres taken up by cells is of key importance to the development of effective nanomedicine. With gold nanospheres as a model system, here we demonstrate, for the first time, how to quantify the numbers of nanospheres bound to plasma membrane, accumulated in cytosol, and entrapped in endo-lysosomes, respectively, through stepwise, site-selective etching. Our results indicate that the chance for nanospheres to escape from endo-lysosomes is insensitive to the presence of targeting ligand although ligand-receptor binding has been documented as a critical factor in triggering internalization. Furthermore, the presence of serum proteins is shown to facilitate the binding of nanospheres to plasma membrane lacking the specific receptor. Collectively, these findings confirm the potential of stepwise etching in quantitatively analyzing the sub-cellular distributions of nanospheres taken up by cells in an effort to optimize the therapeutic effect.
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Affiliation(s)
- Da Huo
- The Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA, 30332, USA
| | - Younan Xia
- The Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA, 30332, USA.,School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA, 30332, USA
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162
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Xu B, Feng T, Li Z, Pantelides ST, Wu Y. Constructing Highly Porous Thermoelectric Monoliths with High-Performance and Improved Portability from Solution-Synthesized Shape-Controlled Nanocrystals. Nano Lett 2018; 18:4034-4039. [PMID: 29804458 DOI: 10.1021/acs.nanolett.8b01691] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Thermoelectricity offers a viable and reliable solution to convert waste heat into electricity. To enhance the performance and portability of thermoelectric materials, the crystal grain and pore structure should be simultaneously manipulated to achieve high electrical conductivity (σ), low thermal conductivity (κ), high figure of merit (zT), and low relative density. However, they cannot be synchronously realized using nanocrystals with uncontrolled domain size and shape as building blocks. Here, we employ solution-synthesized PbS nanocrystals with large grain size, controllable shape and tunable spatial packing to realize the aforementioned structural tuning. The as-sintered highly porous and well crystalline monolith exhibits high σ, low κ, high zT (1.06 at 838 K) and low relative density (82%). The phonon transport is studied by density functional theory highlighting the crucial role of phonon-pore scattering in reducing κ to enhance zT. Our strategy may benefit thermoelectrics and shed light on other technical fields such as catalysis, gas sensing, photovoltaics, and so forth.
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Affiliation(s)
- Biao Xu
- School of Chemical Engineering , Nanjing University of Science and Technology , Nanjing , Jiangsu 210094 , China
- Department of Chemical and Biological Engineering , Iowa State University , Ames , Iowa 50011 , United States
| | - Tianli Feng
- Department of Physics and Astronomy and Department of Electrical Engineering and Computer Science , Vanderbilt University , Nashville , Tennessee 37235 , United States
- Materials Science and Technology Division , Oak Ridge National Laboratory , Oak Ridge , Tennessee 37831 , United States
| | - Zhe Li
- Department of Chemical and Biological Engineering , Iowa State University , Ames , Iowa 50011 , United States
| | - Sokrates T Pantelides
- Department of Physics and Astronomy and Department of Electrical Engineering and Computer Science , Vanderbilt University , Nashville , Tennessee 37235 , United States
- Materials Science and Technology Division , Oak Ridge National Laboratory , Oak Ridge , Tennessee 37831 , United States
| | - Yue Wu
- Department of Chemical and Biological Engineering , Iowa State University , Ames , Iowa 50011 , United States
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163
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Orfield NJ, Majumder S, McBride JR, Yik-Ching Koh F, Singh A, Bouquin SJ, Casson JL, Johnson AD, Sun L, Li X, Shih CK, Rosenthal SJ, Hollingsworth JA, Htoon H. Photophysics of Thermally-Assisted Photobleaching in "Giant" Quantum Dots Revealed in Single Nanocrystals. ACS Nano 2018; 12:4206-4217. [PMID: 29709173 DOI: 10.1021/acsnano.7b07450] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Quantum dots (QDs) are steadily being implemented as down-conversion phosphors in market-ready display products to enhance color rendering, brightness, and energy efficiency. However, for adequate longevity, QDs must be encased in a protective barrier that separates them from ambient oxygen and humidity, and device architectures are designed to avoid significant heating of the QDs as well as direct contact between the QDs and the excitation source. In order to increase the utility of QDs in display technologies and to extend their usefulness to more demanding applications as, for example, alternative phosphors for solid-state lighting (SSL), QDs must retain their photoluminescence emission properties over extended periods of time under conditions of high temperature and high light flux. Doing so would simplify the fabrication costs for QD display technologies and enable QDs to be used as down-conversion materials in light-emitting diodes for SSL, where direct-on-chip configurations expose the emitters to temperatures approaching 100 °C and to photon fluxes from 0.1 W/mm2 to potentially 10 W/mm2. Here, we investigate the photobleaching processes of single QDs exposed to controlled temperature and photon flux. In particular, we investigate two types of room-temperature-stable core/thick-shell QDs, known as "giant" QDs for which shell growth is conducted using either a standard layer-by-layer technique or by a continuous injection method. We determine the mechanistic pathways responsible for thermally-assisted photodegradation, distinguishing effects of hot-carrier trapping and QD charging. The findings presented here will assist in the further development of advanced QD heterostructures for maximum device lifetime stability.
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Affiliation(s)
- Noah J Orfield
- Materials Physics and Applications Division: Center for Integrated Nanotechnologies , Los Alamos National Laboratory , Los Alamos , New Mexico 87545 , United States
| | - Somak Majumder
- Materials Physics and Applications Division: Center for Integrated Nanotechnologies , Los Alamos National Laboratory , Los Alamos , New Mexico 87545 , United States
| | - James R McBride
- Department of Chemistry , Vanderbilt University , Nashville , Tennessee 37235 , United States
| | - Faith Yik-Ching Koh
- Materials Physics and Applications Division: Center for Integrated Nanotechnologies , Los Alamos National Laboratory , Los Alamos , New Mexico 87545 , United States
| | - Ajay Singh
- Materials Physics and Applications Division: Center for Integrated Nanotechnologies , Los Alamos National Laboratory , Los Alamos , New Mexico 87545 , United States
| | - Sarah J Bouquin
- Materials Physics and Applications Division: Center for Integrated Nanotechnologies , Los Alamos National Laboratory , Los Alamos , New Mexico 87545 , United States
| | - Joanna L Casson
- Chemistry Division , Los Alamos National Laboratory , Los Alamos , New Mexico 87545 , United States
| | - Alex D Johnson
- Physics Department and Center for Complex Quantum Systems , University of Texas at Austin , Austin , Texas 78712 , United States
| | - Liuyang Sun
- Physics Department and Center for Complex Quantum Systems , University of Texas at Austin , Austin , Texas 78712 , United States
| | - Xiaoqin Li
- Physics Department and Center for Complex Quantum Systems , University of Texas at Austin , Austin , Texas 78712 , United States
| | - Chih-Kang Shih
- Physics Department and Center for Complex Quantum Systems , University of Texas at Austin , Austin , Texas 78712 , United States
| | - Sandra J Rosenthal
- Department of Chemistry , Vanderbilt University , Nashville , Tennessee 37235 , United States
| | - Jennifer A Hollingsworth
- Materials Physics and Applications Division: Center for Integrated Nanotechnologies , Los Alamos National Laboratory , Los Alamos , New Mexico 87545 , United States
| | - Han Htoon
- Materials Physics and Applications Division: Center for Integrated Nanotechnologies , Los Alamos National Laboratory , Los Alamos , New Mexico 87545 , United States
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164
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Berestok T, Guardia P, Du R, Portals JB, Colombo M, Estradé S, Peiró F, Brock SL, Cabot A. Metal Oxide Aerogels with Controlled Crystallinity and Faceting from the Epoxide-Driven Cross-Linking of Colloidal Nanocrystals. ACS Appl Mater Interfaces 2018; 10:16041-16048. [PMID: 29672016 DOI: 10.1021/acsami.8b03754] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
We present a novel method to produce crystalline oxide aerogels which is based on the cross-linking of preformed colloidal nanocrystals (NCs) triggered by propylene oxide (PO). Ceria and titania were used to illustrate this new approach. Ceria and titania colloidal NCs with tuned geometry and crystal facets were produced in solution from the decomposition of a suitable salt in the presence of oleylamine (OAm). The native surface ligands were replaced by amino acids, rendering the NCs colloidally stable in polar solvents. The NC colloidal solution was then gelled by adding PO, which gradually stripped the ligands from the NC surface, triggering a slow NC aggregation. NC-based metal oxide aerogels displayed both high surface areas and excellent crystallinity associated with the crystalline nature of the constituent building blocks, even without any annealing step. Such NC-based metal oxide aerogels showed higher thermal stability compared with aerogels directly produced from ionic precursors using conventional sol-gel chemistry strategies.
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Affiliation(s)
- Taisiia Berestok
- Catalonia Institute for Energy Research-IREC , 08930 Sant Adrià de Besòs, Barcelona , Spain
- LENS-MIND, Departament d'Enginyeria Electrònica I Biomèdica , Universitat de Barcelona , 08028 Barcelona , Spain
| | - Pablo Guardia
- Catalonia Institute for Energy Research-IREC , 08930 Sant Adrià de Besòs, Barcelona , Spain
| | - Ruifeng Du
- Catalonia Institute for Energy Research-IREC , 08930 Sant Adrià de Besòs, Barcelona , Spain
| | - Javier Blanco Portals
- LENS-MIND, Departament d'Enginyeria Electrònica I Biomèdica , Universitat de Barcelona , 08028 Barcelona , Spain
- Institute of Nanoscience and Nanotechnology (In2UB) , Universitat de Barcelona , 08028 Barcelona , Spain
| | - Massimo Colombo
- Nanochemistry Department , Istituto Italiano di Tecnologia , via Morego 30 , 16130 Genova , Italy
| | - Sònia Estradé
- LENS-MIND, Departament d'Enginyeria Electrònica I Biomèdica , Universitat de Barcelona , 08028 Barcelona , Spain
- Institute of Nanoscience and Nanotechnology (In2UB) , Universitat de Barcelona , 08028 Barcelona , Spain
| | - Francesca Peiró
- LENS-MIND, Departament d'Enginyeria Electrònica I Biomèdica , Universitat de Barcelona , 08028 Barcelona , Spain
- Institute of Nanoscience and Nanotechnology (In2UB) , Universitat de Barcelona , 08028 Barcelona , Spain
| | - Stephanie L Brock
- Department of Chemistry , Wayne State University , Detroit , Michigan 48202 , United States
| | - Andreu Cabot
- Catalonia Institute for Energy Research-IREC , 08930 Sant Adrià de Besòs, Barcelona , Spain
- ICREA , Pg. Lluís Companys 23 , 08010 Barcelona , Spain
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165
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Xiao Z, Sun X, Li X, Wang Y, Wang Z, Zhang B, Li XL, Shen Z, Kong LB, Huang Y. Phase Transformation of GeO 2 Glass to Nanocrystals under Ambient Conditions. Nano Lett 2018; 18:3290-3296. [PMID: 29667834 DOI: 10.1021/acs.nanolett.8b01142] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Theoretically, the accomplishment of phase transformation requires sufficient energy to overcome the barriers of structure rearrangements. The transition of an amorphous structure to a crystalline structure is implemented traditionally by heating at high temperatures. However, phase transformation under ambient condition without involving external energy has not been reported. Here, we demonstrate that the phase transformation of GeO2 glass to nanocrystals can be triggered at ambient conditions when subjected to aqueous environments. In this case, continuous chemical reactions between amorphous GeO2 and water are responsible for the amorphous-to-crystalline transition. The dynamic evolution process is monitored by using in situ liquid-cell transmission electron microscopy, clearly revealing this phase transformation. It is the hydrolysis of amorphous GeO2 that leads to the formation of clusters with a size of ∼0.4 nm, followed by the development of dense liquid clusters, which subsequently aggregate to facilitate the nucleation and growth of GeO2 nanocrystals. Our finding breaks the traditional understanding of phase transformation and will bring about a significant revolution and contribution to the classical glass-crystallization theories.
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Affiliation(s)
- Zhuohao Xiao
- School of Materials Science and Engineering , Jingdezhen Ceramic Institute , Jingdezhen 333001 , China
| | - Xinyuan Sun
- Department of Physics , Jinggangshan University , Ji'an 343009 , China
| | - Xiuying Li
- School of Materials Science and Engineering , Jingdezhen Ceramic Institute , Jingdezhen 333001 , China
| | - Yongqing Wang
- School of Materials Science and Engineering , Jingdezhen Ceramic Institute , Jingdezhen 333001 , China
| | - Zhiqiang Wang
- School of Materials Science and Engineering , Nanyang Technological University , Singapore 639798 , Singapore
| | - Bowei Zhang
- School of Materials Science and Engineering , Nanyang Technological University , Singapore 639798 , Singapore
| | - Xiang Lin Li
- School of Materials Science and Engineering , Nanyang Technological University , Singapore 639798 , Singapore
| | - Zexiang Shen
- School of Materials Science and Engineering , Nanyang Technological University , Singapore 639798 , Singapore
| | - Ling Bing Kong
- School of Materials Science and Engineering , Nanyang Technological University , Singapore 639798 , Singapore
| | - Yizhong Huang
- School of Materials Science and Engineering , Nanyang Technological University , Singapore 639798 , Singapore
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166
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Zhang M, Guo J, Yu Y, Wu Y, Yun H, Jishkariani D, Chen W, Greybush NJ, Kübel C, Stein A, Murray CB, Kagan CR. 3D Nanofabrication via Chemo-Mechanical Transformation of Nanocrystal/Bulk Heterostructures. Adv Mater 2018; 30:e1800233. [PMID: 29658166 DOI: 10.1002/adma.201800233] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/12/2018] [Revised: 02/08/2018] [Indexed: 06/08/2023]
Abstract
Planar nanocrystal/bulk heterostructures are transformed into 3D architectures by taking advantage of the different chemical and mechanical properties of nanocrystal and bulk thin films. Nanocrystal/bulk heterostructures are fabricated via bottom-up assembly and top-down fabrication. The nanocrystals are capped by long ligands introduced in their synthesis, and therefore their surfaces are chemically addressable, and their assemblies are mechanically "soft," in contrast to the bulk films. Chemical modification of the nanocrystal surface, exchanging the long ligands for more compact chemistries, triggers large volume shrinkage of the nanocrystal layer and drives bending of the nanocrystal/bulk heterostructures. Exploiting the differential chemo-mechanical properties of nanocrystal and bulk materials, the scalable fabrication of designed 3D, cell-sized nanocrystal/bulk superstructures is demonstrated, which possess unique functions derived from nanocrystal building blocks.
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Affiliation(s)
- Mingliang Zhang
- Department of Electrical and Systems Engineering, University of Pennsylvania, Philadelphia, PA, 19104, USA
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA, 19104, USA
- Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Jiacen Guo
- Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Yao Yu
- Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Yaoting Wu
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Hongseok Yun
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Davit Jishkariani
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Wenxiang Chen
- Department of Electrical and Systems Engineering, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Nicholas J Greybush
- Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Christian Kübel
- Karlsruhe Nano Micro Facility and Institute of Nanotechnology, Karlsruhe Institute of Technology, 76344, Eggenstein-Leopoldshafen, Germany
| | - Aaron Stein
- Center for Functional Nanomaterials, Brookhaven National Laboratory, Upton, NY, 11973, USA
| | - Christopher B Murray
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA, 19104, USA
- Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Cherie R Kagan
- Department of Electrical and Systems Engineering, University of Pennsylvania, Philadelphia, PA, 19104, USA
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA, 19104, USA
- Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, PA, 19104, USA
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167
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Liu Y, Zhang Y, Ortega S, Ibáñez M, Lim KH, Grau-Carbonell A, Martí-Sánchez S, Ng KM, Arbiol J, Kovalenko MV, Cadavid D, Cabot A. Crystallographically Textured Nanomaterials Produced from the Liquid Phase Sintering of Bi xSb 2- xTe 3 Nanocrystal Building Blocks. Nano Lett 2018; 18:2557-2563. [PMID: 29546994 DOI: 10.1021/acs.nanolett.8b00263] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Bottom-up approaches for producing bulk nanomaterials have traditionally lacked control over the crystallographic alignment of nanograins. This limitation has prevented nanocrystal-based nanomaterials from achieving optimized performances in numerous applications. Here we demonstrate the production of nanostructured Bi xSb2- xTe3 alloys with controlled stoichiometry and crystallographic texture through proper selection of the starting building blocks and the adjustment of the nanocrystal-to-nanomaterial consolidation process. In particular, we hot pressed disk-shaped Bi xSb2- xTe3 nanocrystals and tellurium nanowires using multiple pressure and release steps at a temperature above the tellurium melting point. We explain the formation of the textured nanomaterials though a solution-reprecipitation mechanism under a uniaxial pressure. Additionally, we further demonstrate these alloys to reach unprecedented thermoelectric figures of merit, up to ZT = 1.96 at 420 K, with an average value of ZTave = 1.77 for the record material in the temperature range 320-500 K, thus potentially allowing up to 60% higher energy conversion efficiencies than commercial materials.
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Affiliation(s)
- Yu Liu
- Catalonia Energy Research Institute - IREC , Sant Adria de Besòs , 08930 Barcelona , Spain
| | - Yu Zhang
- Catalonia Energy Research Institute - IREC , Sant Adria de Besòs , 08930 Barcelona , Spain
| | - Silvia Ortega
- Catalonia Energy Research Institute - IREC , Sant Adria de Besòs , 08930 Barcelona , Spain
| | - Maria Ibáñez
- Institute of Inorganic Chemistry, Department of Chemistry and Applied Biosciences , ETH Zürich , Vladimir Prelog Weg 1 , CH-8093 Zürich , Switzerland
- Empa-Swiss Federal Laboratories for Materials Science and Technology, Dübendorf , Überlandstrasse 129 , CH-8600 Dübendorf , Switzerland
| | - Khak Ho Lim
- Department of Chemical and Biological Engineering , Hong Kong University of Science and Technology , Hong Kong , China
| | - Albert Grau-Carbonell
- Catalan Institute of Nanoscience and Nanotechnology (ICN2) , CSIC and BIST , Campus UAB, Bellaterra, 08193 Barcelona , Catalonia , Spain
| | - Sara Martí-Sánchez
- Catalan Institute of Nanoscience and Nanotechnology (ICN2) , CSIC and BIST , Campus UAB, Bellaterra, 08193 Barcelona , Catalonia , Spain
| | - Ka Ming Ng
- Department of Chemical and Biological Engineering , Hong Kong University of Science and Technology , Hong Kong , China
| | - Jordi Arbiol
- Catalan Institute of Nanoscience and Nanotechnology (ICN2) , CSIC and BIST , Campus UAB, Bellaterra, 08193 Barcelona , Catalonia , Spain
- ICREA , Pg. Lluis Companys 23 , 08010 Barcelona , Spain
| | - Maksym V Kovalenko
- Institute of Inorganic Chemistry, Department of Chemistry and Applied Biosciences , ETH Zürich , Vladimir Prelog Weg 1 , CH-8093 Zürich , Switzerland
- Empa-Swiss Federal Laboratories for Materials Science and Technology, Dübendorf , Überlandstrasse 129 , CH-8600 Dübendorf , Switzerland
| | - Doris Cadavid
- Catalonia Energy Research Institute - IREC , Sant Adria de Besòs , 08930 Barcelona , Spain
- Departamento de Física , Universidad Nacional de Colombia , 111321 Ciudad Universitaria, Bogotá , Colombia
| | - Andreu Cabot
- Catalonia Energy Research Institute - IREC , Sant Adria de Besòs , 08930 Barcelona , Spain
- ICREA , Pg. Lluis Companys 23 , 08010 Barcelona , Spain
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168
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Henckel DA, Lenz OM, Krishnan KM, Cossairt BM. Improved HER Catalysis through Facile, Aqueous Electrochemical Activation of Nanoscale WSe 2. Nano Lett 2018; 18:2329-2335. [PMID: 29498869 DOI: 10.1021/acs.nanolett.7b05213] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
In the search for nonprecious metal catalysts for the hydrogen evolution reaction (HER), transition metal dichalcogenides (TMDCs) have been proposed as promising candidates. Here, we present a facile method for significantly decreasing the overpotential required for catalyzing the HER with colloidally synthesized WSe2. Solution phase deposition of 2H WSe2 nanoflowers (NFs) onto carbon fiber electrodes results in low catalytic activity in 0.5 M H2SO4 with an overpotential at -10 mA/cm2 of greater than 600 mV. However, two postdeposition electrode processing steps significantly reduce the overpotential. First, a room-temperature treatment of the prepared electrodes with a dilute solution of the alkylating agent Meerwein's salt ([Et3O][BF4]) results in a reduction in overpotential by approximately 130 mV at -10 mA/cm2. Second, we observe a decrease in overpotential of approximately 200-300 mV when the TMDC electrode is exposed to H+, Li+, Na+, or K+ ions under a reducing potential. The combined effect of ligand removal and electrochemical activation results in an improvement in overpotential by as much as 400 mV. Notably, the Li+ activated WSe2 NF deposited carbon fiber electrode requires an overpotential of only 243 mV to generate a current density of -10 mA/cm2. Measurement of changes in the material work function and charge transfer resistance ultimately provide rationale for the catalytic improvement.
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Affiliation(s)
- Danielle A Henckel
- Department of Chemistry , University of Washington , Box 351700, Bagley Hall, Seattle , Washington 98195-1700 , United States
| | - Olivia M Lenz
- Department of Materials Science and Engineering , University of Washington , Box 352120, Roberts Hall, Seattle , Washington 98195-1700 , United States
| | - Kannan M Krishnan
- Department of Materials Science and Engineering , University of Washington , Box 352120, Roberts Hall, Seattle , Washington 98195-1700 , United States
| | - Brandi M Cossairt
- Department of Chemistry , University of Washington , Box 351700, Bagley Hall, Seattle , Washington 98195-1700 , United States
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169
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Lim S, Choi B, Lee SY, Lee S, Nahm HH, Kim YH, Kim T, Park JG, Lee J, Hong J, Kwon SG, Hyeon T. Microscopic States and the Verwey Transition of Magnetite Nanocrystals Investigated by Nuclear Magnetic Resonance. Nano Lett 2018; 18:1745-1750. [PMID: 29461844 DOI: 10.1021/acs.nanolett.7b04866] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
57Fe nuclear magnetic resonance (NMR) of magnetite nanocrystals ranging in size from 7 nm to 7 μm is measured. The line width of the NMR spectra changes drastically around 120 K, showing microscopic evidence of the Verwey transition. In the region above the transition temperature, the line width of the spectrum increases and the spin-spin relaxation time decreases as the nanocrystal size decreases. The line-width broadening indicates the significant deformation of magnetic structure and reduction of charge order compared to bulk crystals, even when the structural distortion is unobservable. The reduction of the spin-spin relaxation time is attributed to the suppressed polaron hopping conductivity in ferromagnetic metals, which is a consequence of the enhanced electron-phonon coupling in the quantum-confinement regime. Our results show that the magnetic distortion occurs in the entire nanocrystal and does not comply with the simple model of the core-shell binary structure with a sharp boundary.
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170
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Chen L, Li B, Zhang C, Huang X, Wang X, Xiao M. Composition-Dependent Energy Splitting between Bright and Dark Excitons in Lead Halide Perovskite Nanocrystals. Nano Lett 2018; 18:2074-2080. [PMID: 29464960 DOI: 10.1021/acs.nanolett.8b00184] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Perovskite semiconductor nanocrystals with different compositions have shown promise for applications in light-emitting devices. Dark excitonic states may suppress light emission from such nanocrystals by providing an additional nonradiative recombination channel. Here, we study the composition dependence of dark exciton dynamics in nanocrystals of lead halides by time-resolved photoluminescence spectroscopy at cryogenic temperatures. The presence of a spin-related dark state is revealed by magneto-optical spectroscopy. The energy splitting between bright and dark states is found to be highly sensitive to both halide elements and organic cations, which is explained by considering the effects of size confinement and charge screening, respectively, on the exchange interaction. These findings suggest the possibility of manipulating dark exciton dynamics in perovskite semiconductor nanocrystals by composition engineering, which will be instrumental in the design of highly efficient light-emitting devices.
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Affiliation(s)
- Lan Chen
- National Laboratory of Solid State Microstructures, School of Physics & Collaborative Innovation Center of Advanced Microstructures , Nanjing University , Nanjing 210093 , China
| | - Bin Li
- National Laboratory of Solid State Microstructures, School of Physics & Collaborative Innovation Center of Advanced Microstructures , Nanjing University , Nanjing 210093 , China
| | - Chunfeng Zhang
- National Laboratory of Solid State Microstructures, School of Physics & Collaborative Innovation Center of Advanced Microstructures , Nanjing University , Nanjing 210093 , China
- Synergetic Innovation Center in Quantum Information and Quantum Physics , University of Science and Technology of China , Hefei , Anhui 230026 , China
| | - Xinyu Huang
- National Laboratory of Solid State Microstructures, School of Physics & Collaborative Innovation Center of Advanced Microstructures , Nanjing University , Nanjing 210093 , China
| | - Xiaoyong Wang
- National Laboratory of Solid State Microstructures, School of Physics & Collaborative Innovation Center of Advanced Microstructures , Nanjing University , Nanjing 210093 , China
| | - Min Xiao
- National Laboratory of Solid State Microstructures, School of Physics & Collaborative Innovation Center of Advanced Microstructures , Nanjing University , Nanjing 210093 , China
- Synergetic Innovation Center in Quantum Information and Quantum Physics , University of Science and Technology of China , Hefei , Anhui 230026 , China
- Department of Physics , University of Arkansas , Fayetteville , Arkansas 72701 , United States
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171
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You J, Chen Y, Mohamed Alsayeh ZM, Shen X, Li C, Zhao P, Chen F, Liu Y, Xu C. Nanocrystals of a new camptothecin derivative WCN-21 enhance its solubility and efficacy. Oncotarget 2018; 8:29808-29822. [PMID: 28423733 PMCID: PMC5444705 DOI: 10.18632/oncotarget.16159] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2016] [Accepted: 02/23/2017] [Indexed: 11/25/2022] Open
Abstract
WCN-21 is a new camptothecin derivative we synthesized and has desirable anti-tumor efficacy, but its aqueous solubility is very low and hurdles the further evaluation and development. In this study, we prepared nanocrystals of WCN-21 through a bottom-up approach to enhance its solubility and obtained WCN-21 nanorods (WND) and nanospheres (WNP). We investigated the crystallization of WND and WNP in different temperature and solvents and found that both temperature and solvents affect the crystal shapes and sizes. We prepared WND at 50°C and DMSO : H2O 1: 50 and WNP at 25°C and DMSO : H2O 1: 100 and found they were dispersed evenly in water with average hydrodynamic diameters 337 and 231 nm, respectively. WND and WNP increased the solubility of WCN-21 from extreme insolubility to more than 9 and 11 mM in H2O or PBS, respectively. In vitro studies showed that WND and WNP enhanced the uptake of WCN-21 in tumor cells by 3 and 9 folds, and increased cytotoxicity of WCN-21 in comparison with free WCN-21 by 5 and 6 folds, respectively. In xenograft tumor mice, intravenous injection of WND and WNP enhanced the accumulation of WCN-21 in tumor tissues and improved the anti-tumor efficacy. In addition, WND and WNP did not increase the toxicity of WCN-21 in mice. Therefore, nanocrystal is a robust tool to improve the solubility of insoluble drugs and holds a great potential in the application of drug development.
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Affiliation(s)
- Jia You
- School of Pharmacy, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, P. R. China
| | - Yuyuan Chen
- School of Pharmacy, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, P. R. China
| | - Zubaeda M Mohamed Alsayeh
- School of Pharmacy, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, P. R. China
| | - Xingyu Shen
- School of Pharmacy, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, P. R. China
| | - Chun Li
- School of Pharmacy, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, P. R. China
| | - Pengxuan Zhao
- School of Pharmacy, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, P. R. China
| | - Fei Chen
- Max Planck Institute for Polymer Research, 55128 Mainz, Germany
| | - Yingqian Liu
- School of Pharmacy, Lanzhou University, Lanzhou, 730000, P. R. China
| | - Chuanrui Xu
- School of Pharmacy, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, P. R. China
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172
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Zhao Q, Zhao T, Guo J, Chen W, Zhang M, Kagan CR. The Effect of Dielectric Environment on Doping Efficiency in Colloidal PbSe Nanostructures. ACS Nano 2018; 12:1313-1320. [PMID: 29346726 DOI: 10.1021/acsnano.7b07602] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Doping, as a central strategy to control free carrier type and concentration in semiconductor materials, suffers from low efficiency at the nanoscale, especially in systems having high permittivity (ϵ) and large Bohr radii, such as lead chalcogenide nanocrystals (NCs) and nanowires (NWs). Here, we study dielectric confinement effects on the doping efficiency of lead chalcogenides nanostructures by integrating PbSe NWs in the platform of field effect transistors (FETs). Elemental Pb or In or elemental Se is deposited by thermal evaporation to remotely n- or p-dope the NWs. Polymeric and oxide materials of varying ϵ are subsequently deposited to control the dielectric environment surrounding the NWs. Analyzing the device characteristics, we extract the change of carrier concentration introduced by tailoring the dielectric environment. The calculated doping efficiency for n-type (Pb/In) and p-type (Se) dopants increases as the ϵ of the surrounding medium increases. Using a high-ϵ material, such as HfO2 for encapsulation, the doping efficiency can be enhanced by >10-fold. A theoretical model is built to describe the doping efficiency in PbSe NWs embedded in different dielectric environments, which agrees with our experimental data for both NW array and single NW devices. As dielectric confinement affects all low-dimensional materials, engineering the dielectric environment is a promising general approach to enhance doping concentrations, without introducing excess impurities that may scatter carriers, and is suitable for various device applications.
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Affiliation(s)
- Qinghua Zhao
- Department of Chemistry, ‡Department of Materials Science and Engineering, and §Department of Electrical and Systems Engineering, University of Pennsylvania , Philadelphia, Pennsylvania 19104, United States
| | - Tianshuo Zhao
- Department of Chemistry, ‡Department of Materials Science and Engineering, and §Department of Electrical and Systems Engineering, University of Pennsylvania , Philadelphia, Pennsylvania 19104, United States
| | - Jiacen Guo
- Department of Chemistry, ‡Department of Materials Science and Engineering, and §Department of Electrical and Systems Engineering, University of Pennsylvania , Philadelphia, Pennsylvania 19104, United States
| | - Wenxiang Chen
- Department of Chemistry, ‡Department of Materials Science and Engineering, and §Department of Electrical and Systems Engineering, University of Pennsylvania , Philadelphia, Pennsylvania 19104, United States
| | - Mingliang Zhang
- Department of Chemistry, ‡Department of Materials Science and Engineering, and §Department of Electrical and Systems Engineering, University of Pennsylvania , Philadelphia, Pennsylvania 19104, United States
| | - Cherie R Kagan
- Department of Chemistry, ‡Department of Materials Science and Engineering, and §Department of Electrical and Systems Engineering, University of Pennsylvania , Philadelphia, Pennsylvania 19104, United States
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173
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Yoshioka C, Ito Y, Nagai N. Enhanced percutaneous absorption of cilostazol nanocrystals using aqueous gel patch systems and clarification of the absorption mechanism. Exp Ther Med 2018; 15:3501-3508. [PMID: 29545875 DOI: 10.3892/etm.2018.5820] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2017] [Accepted: 01/12/2018] [Indexed: 12/19/2022] Open
Abstract
Cilostazol (CLZ), an anti-platelet agent, is primarily used following the onset of cerebral infarction. However, as CLZ is only marginally soluble in water, a strategy for patients with serious secondary conditions, such as impaired consciousness or aphagia, is required. In the present study, topical formulations containing CLZ nanocrystals (CLZnano) were designed to enhance percutaneous absorption. In addition, the mechanism of penetration of CLZnano through rat skin was investigated. A topical formulation containing CLZ nanoparticles (CLZnano gel patch) was prepared using a combination of recrystallization and ball milling of an aqueous gel. The particle size of CLZnano was 74.5±6.2 nm (mean ± standard deviation). The concentration of permeated CLZnano and penetration mechanism of the nanocrystals were measured in a percutaneous absorption experiment. The amount of penetrated CLZ, the penetration rate (Jc), the penetration coefficient through the skin (Kp) and the skin/preparation partition coefficient (Km) for the CLZnano gel patch were all significantly higher than those of the CLZ powder (CLZmicro) gel patch, the CLZnano ointment and the CLZmicro ointment. In in vitro percutaneous penetration experiments on the CLZnano gel patches, there was a positive correlation between the number of CLZnano. Following the application of the CLZnano gel patch on rat skin, 98% of penetrated CLZ was observed in nanoparticle form; for the CLZmicro gel patch, this figure was 9%. In addition, the CLZ concentrations in the plasma of rats administered the CLZnano gel patches were significantly higher than those of rats administered the CLZnano CP gel and PEG ointments. It was suggested that CLZnano (diameter <100 nm) were transferred through the intracellular spaces in the skin and then into peripheral blood vessels. To the best of our knowledge, this is the first report to elucidate the mechanism of the percutaneous penetration of nanocrystal medicines.
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Affiliation(s)
- Chiaki Yoshioka
- Faculty of Pharmacy, Kindai University, Higashi-Osaka, Osaka 577-8502, Japan
| | - Yoshimasa Ito
- Faculty of Pharmacy, Kindai University, Higashi-Osaka, Osaka 577-8502, Japan
| | - Noriaki Nagai
- Faculty of Pharmacy, Kindai University, Higashi-Osaka, Osaka 577-8502, Japan
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174
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Gorni G, Velázquez JJ, Mosa J, Balda R, Fernández J, Durán A, Castro Y. Transparent Glass-Ceramics Produced by Sol-Gel: A Suitable Alternative for Photonic Materials. Materials (Basel) 2018; 11:E212. [PMID: 29385706 DOI: 10.3390/ma11020212] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/11/2018] [Revised: 01/26/2018] [Accepted: 01/27/2018] [Indexed: 11/16/2022]
Abstract
Transparent glass-ceramics have shown interesting optical properties for several photonic applications. In particular, compositions based on oxide glass matrices with fluoride crystals embedded inside, known as oxyfluoride glass-ceramics, have gained increasing interest in the last few decades. Melt-quenching is still the most used method to prepare these materials but sol-gel has been indicated as a suitable alternative. Many papers have been published since the end of the 1990s, when these materials were prepared by sol-gel for the first time, thus a review of the achievements obtained so far is necessary. In the first part of this paper, a review of transparent sol-gel glass-ceramics is made focusing mainly on oxyfluoride compositions. Many interesting optical results have been obtained but very little innovation of synthesis and processing is found with respect to pioneering papers published 20 years ago. In the second part we describe the improvements in synthesis and processing obtained by the authors during the last five years. The main achievements are the preparation of oxyfluoride glass-ceramics with a much higher fluoride crystal fraction, at least double that reported up to now, and the first synthesis of NaGdF4 glass-ceramics. Moreover, a new SiO2 precursor was introduced in the synthesis, allowing for a reduction in the treatment temperature and favoring hydroxyl group removal. Interesting optical properties demonstrated the incorporation of dopant ions in the fluoride crystals, thus obtaining crystal-like spectra along with higher efficiencies with respect to xerogels, and hence demonstrating that these materials are a suitable alternative for photonic applications.
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175
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de Jong EMLD, Rutjes H, Valenta J, Trinh MT, Poddubny AN, Yassievich IN, Capretti A, Gregorkiewicz T. Thermally stimulated exciton emission in Si nanocrystals. Light Sci Appl 2018; 7:17133. [PMID: 30839625 PMCID: PMC6107050 DOI: 10.1038/lsa.2017.133] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/27/2017] [Revised: 09/14/2017] [Accepted: 09/15/2017] [Indexed: 06/09/2023]
Abstract
Increasing temperature is known to quench the excitonic emission of bulk silicon, which is due to thermally induced dissociation of excitons. Here, we demonstrate that the effect of temperature on the excitonic emission is reversed for quantum-confined silicon nanocrystals. Using laser-induced heating of silicon nanocrystals embedded in SiO2, we achieved a more than threefold (>300%) increase in the radiative (photon) emission rate. We theoretically modeled the observed enhancement in terms of the thermally stimulated effect, taking into account the massive phonon production under intense illumination. These results elucidate one more important advantage of silicon nanostructures, illustrating that their optical properties can be influenced by temperature. They also provide an important insight into the mechanisms of energy conversion and dissipation in ensembles of silicon nanocrystals in solid matrices. In practice, the radiative rate enhancement under strong continuous wave optical pumping is relevant for the possible application of silicon nanocrystals for spectral conversion layers in concentrator photovoltaics.
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Affiliation(s)
- Elinore MLD de Jong
- Van der Waals-Zeeman Institute, University of Amsterdam, Science Park 904, 1098 XH, Amsterdam, The Netherlands
| | - Huub Rutjes
- Van der Waals-Zeeman Institute, University of Amsterdam, Science Park 904, 1098 XH, Amsterdam, The Netherlands
| | - Jan Valenta
- Department of Chemical Physics and Optics, Faculty of Mathematics and Physics, Charles University, Ke Karlovu 3, 121 16 Prague 2, Czech Republic
| | - M Tuan Trinh
- Department of Electrical Engineering and Computer Science, University of Michigan, 2200 Bonisteel Blvd, Ann Arbor, MI 48109, USA
| | - Alexander N Poddubny
- Ioffe Institute, Russian Academy of Sciences, 26 Polytechnicheskaya, 194021 St Petersburg, Russia
| | - Irina N Yassievich
- Ioffe Institute, Russian Academy of Sciences, 26 Polytechnicheskaya, 194021 St Petersburg, Russia
| | - Antonio Capretti
- Van der Waals-Zeeman Institute, University of Amsterdam, Science Park 904, 1098 XH, Amsterdam, The Netherlands
| | - Tom Gregorkiewicz
- Van der Waals-Zeeman Institute, University of Amsterdam, Science Park 904, 1098 XH, Amsterdam, The Netherlands
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176
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Wu YZ, Sun J, Yang H, Zhao X, He D, Pu M, Zhang G, He N, Zeng X. Biosynthetic Mechanism of Luminescent ZnO Nanocrystals in the Mammalian Blood Circulation and Their Functionalization for Tumor Therapy. ACS Appl Mater Interfaces 2018; 10:105-113. [PMID: 29281248 DOI: 10.1021/acsami.7b13691] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The biosynthesis of nanoparticles in bioreactors using microbial, plant, or animal cells is at the forefront of nanotechnology. We demonstrated for the first time that luminescent, water-soluble ZnO nanocrystals (bio-ZnO NCs) can be spontaneously biosynthesized in the mammalian blood circulation, not in cells, when animals were fed with Zn(CH3COO)2 aqueous solution. Serum albumin, rather than metallothioneins or glutathione, proved to play the pivotal role in biosynthesis. The bio-ZnO NCs were gradually taken up in the liver and degraded and excreted in the urine. Thus, we propose that in mammals such as rodents, bovinae, and humans, excess metal ions absorbed into the cardiovascular system via the intestine can be transformed into nanoparticles by binding to serum albumin, forming a "provisional metal-pool", to reduce the toxicity of free metal ions at high concentration and regulate metal homeostasis in the body. Furthermore, the bio-ZnO NCs, which showed favorable biocompatibility, were functionalized with the anticancer drug daunorubicin and effectively achieved controlled drug release mediated by intracellular glutathione in tumor xenograft mice.
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Affiliation(s)
| | | | - Haowen Yang
- Department of Chemistry and Applied Biosciences, Institute for Chemical and Bioengineering, ETH Zürich , Zurich 8093, Switzerland
| | - Xiaohui Zhao
- Key Laboratory of Tibetan Medicine Research, Northwest Institute of Plateau Biology, Chinese Academy of Sciences , Xining 810001, China
| | - Dacheng He
- Department of Cell Biology, College of Life Science, Beijing Normal University , Beijing 100875, China
| | | | | | - Nongyue He
- The State Key Laboratory of Bioelectronics, Department of Biological Science and Medical Engineering, Southeast University , Nanjing 210096, China
| | - Xin Zeng
- Nanjing Maternity and Child Health Medical Institute, Obstetrics and Gynecology Hospital Affiliated to Nanjing Medical University , Nanjing 210004, China
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177
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Abstract
The optical response of ZnO nanocrystals (NCs) doped with Al (Ga) impurities is calculated using a model that incorporates the effects of quantum confinement, dielectric mismatch, surface, and ionized impurity scattering. For dopant concentrations of a few percent, the NC polarizability is dominated by a localized surface plasmon resonance (LSPR) in the infrared (IR) which follows the Drude-Lorentz law for NC diameter above ∼10 nm but is strongly blue-shifted for smaller diameters due to quantum confinement effects. The intrinsic width of the LSPR peak is calculated in order to characterize plasmon losses induced by ionized impurity scattering. Widths below 80 meV are found in the best cases, in agreement with the lowest values recently measured on single NCs. These results confirm that doped ZnO NCs are very promising for the development of IR plasmonics. The width of the LSPR peak strongly increases when dopants are placed near the surface of the NCs or when additional fixed charges are present.
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Affiliation(s)
- Christophe Delerue
- Univiversity Lille, CNRS, Centrale Lille, ISEN, University Valenciennes , UMR 8520-IEMN, F-59000 Lille, France
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178
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Lee TH, Hwang HG, Jang S, Wang G, Han S, Kim DH, Kang CY, Nahm S. Low-Temperature-Grown KNbO 3 Thin Films and Their Application to Piezoelectric Nanogenerators and Self-Powered ReRAM Device. ACS Appl Mater Interfaces 2017; 9:43220-43229. [PMID: 29144121 DOI: 10.1021/acsami.7b11519] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Amorphous KNbO3 (KN) film containing KN nanocrystals was grown on TiN/SiO2/Si substrate at 350 °C. This KN film showed a dielectric constant (εr) and a piezoelectric strain constant (d33) of 43 and 80 pm/V at 10 V, respectively, owing to the existence of KN nanocrystals. Piezoelectric nanogenerators (PNGs) were fabricated using KN films grown on the TiN/polyimide/poly(ethylene terephthalate) substrates. The PNG fabricated with the KN film grown at 350 °C showed an open-circuit output voltage of 2.5 V and a short-circuit current of 70 nA. The KN film grown at 350 °C exhibited a bipolar resistive switching behavior with good reliability characteristics that can be explained by the formation and rupture of the oxygen vacancy filaments. The KN resistive random access memory device powered by the KN PNG also showed promising resistive switching behavior. Moreover, the KN film shows good biocompatibility. Therefore, the KN film can be used for self-powered biomedical devices.
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Affiliation(s)
| | | | | | | | | | | | - Chong-Yun Kang
- Electronic Materials Center, KIST , 39-1 Hawolkok-dong, Seongbuk-gu, Seoul 137-791, Republic of Korea
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179
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Oka N, Ishimaru M, Tane M, Sina Y, McHargue CJ, Sickafus KE, Alves E. Formation of metastable phases in Zr-ion-irradiated Al2O3 upon thermal annealing. Microscopy (Oxf) 2017; 66:388-396. [PMID: 28992044 DOI: 10.1093/jmicro/dfx028] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2017] [Accepted: 07/11/2017] [Indexed: 06/07/2023] Open
Abstract
Formation of metastable phases in Zr-ion-irradiated corundum alumina (Al2O3) upon thermal annealing was examined using transmission electron microscopy. A metastable cubic spinel phase was formed in the topmost layer of the as-irradiated microstructure. During thermal annealing at temperatures ranging from 1073 to 1273 K, this spinel layer grew in extent via an unusual corundum-to-spinel phase transformation. A normal spinel-to-corundum phase transformation was observed at post-irradiation annealing temperatures greater than 1473 K. In addition, ZrO2 nanocrystals embedded in α-Al2O3 were observed to form at these higher temperatures. High-resolution transmission electron microscopy observations and electron diffraction experiments revealed that the structure of the ZrO2 precipitates observed in this study are consistent with a high-pressure metastable orthorhombic phase of ZrO2 known as the Ortho-I phase.
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Affiliation(s)
- Naomasa Oka
- Department of Materials Science and Engineering, Kyushu Institute of Technology, Fukuoka 804-8550, Japan
| | - Manabu Ishimaru
- Department of Materials Science and Engineering, Kyushu Institute of Technology, Fukuoka 804-8550, Japan
| | - Masakazu Tane
- The Institute of Scientific and Industrial Research, Osaka University, Osaka 567-0047, Japan
| | - Younes Sina
- Materials Science and Engineering Department, University of Tennessee, Knoxville, TN 37996-2200, USA
| | - Carl J McHargue
- Materials Science and Engineering Department, University of Tennessee, Knoxville, TN 37996-2200, USA
| | - Kurt E Sickafus
- Materials Science and Engineering Department, University of Tennessee, Knoxville, TN 37996-2200, USA
| | - Eduardo Alves
- Unit of Physics and Accelerators, Ion Beam Laboratory, Instituto Superior Técnico/Instituto Tecnológico e Nuclear, EN. 10, 2686-953 Sacavém, Portugal
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180
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Abstract
We present a detailed analysis of the interaction between two nanocrystals capped with ligands consisting of hydrocarbon chains by united atom molecular dynamics simulations. We show that the bonding of two nanocrystals is characterized by ligand textures in the form of vortices. These results are generalized to nanocrystals of different types (differing core and ligand sizes) where the structure of the vortices depends on the softness asymmetry. We provide rigorous calculations for the binding free energy, show that these energies are independent of the chemical composition of the cores, and derive analytical formulas for the equilibrium separation. We discuss the implications of our results for the self-assembly of single-component and binary nanoparticle superlattices. Overall, our results show that the structure of the ligands completely determines the bonding of nanocrystals, fully supporting the predictions of the recently proposed Orbifold topological model.
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Affiliation(s)
- Curt Waltmann
- Department of Materials Science and Engineering and Ames Laboratory, Iowa State University , Ames, Iowa 50011, United States
| | - Nathan Horst
- Department of Materials Science and Engineering and Ames Laboratory, Iowa State University , Ames, Iowa 50011, United States
| | - Alex Travesset
- Department of Materials Science and Engineering and Ames Laboratory, Iowa State University , Ames, Iowa 50011, United States
- Department of Physics and Astronomy and Ames Laboratory, Iowa State University , Ames, Iowa 50011, United States
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181
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Abstract
Frequency upconversion activated with lanthanide has attracted attention in various real-world applications, because it is far simpler and more efficient than traditional nonlinear susceptibility-based frequency upconversion, such as second harmonic generation. However, the quantum yield of frequency upconversion of lanthanide-based upconversion nanocrystals remains inefficient for practical applications, and spatial control of upconverted emission is not yet developed. Here, we developed an asymmetric nanocrescent antenna on upconversion nanocrystal (ANAU) to deliver excitation light effectively to the core of upconversion nanocrystal by nanofocusing light and generating asymmetric frequency upconverted emission concentrated toward the tip region. ANAUs were fabricated by high-angle deposition (60°) of gold (Au) on the isolated upconversion nanoparticles supported by nanopillars then moved to refractive-index matched substrate for orientation-dependent upconversion luminescence analysis in the single-nanoparticle scale. We studied shape-dependent nanofocusing efficiency of nanocrescent antennae as a function of the tip-to-tip distance by modulating the deposition angle. The generation of asymmetric frequency upconverted emission toward the tip region was simulated by the asymmetric far-field radiation pattern of dipoles in the nanocrescent antenna and experimentally demonstrated by the orientation-dependent photon intensity of frequency upconverted emission of an ANAU. This finding provides a new way to improve frequency upconversion using an antenna, which locally increases the excitation light and generates the radiation power to certain directions for various applications.
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Affiliation(s)
- Doyeon Bang
- Berkeley Sensor and Actuator Center, Department of Bioengineering, §Department of Electrical Engineering and Computer Science, Biophysics Graduate Program, University of California at Berkeley , Berkeley, California 94720, United States
- Department of Chemistry, School of Physics and Chemistry, ⊥School of Materials Science and Engineering, Gwangju Institute of Science and Technology (GIST) , Gwangju 500-712, Republic of Korea
| | - Eun-Jung Jo
- Berkeley Sensor and Actuator Center, Department of Bioengineering, §Department of Electrical Engineering and Computer Science, Biophysics Graduate Program, University of California at Berkeley , Berkeley, California 94720, United States
- Department of Chemistry, School of Physics and Chemistry, ⊥School of Materials Science and Engineering, Gwangju Institute of Science and Technology (GIST) , Gwangju 500-712, Republic of Korea
| | - SoonGweon Hong
- Berkeley Sensor and Actuator Center, Department of Bioengineering, §Department of Electrical Engineering and Computer Science, Biophysics Graduate Program, University of California at Berkeley , Berkeley, California 94720, United States
- Department of Chemistry, School of Physics and Chemistry, ⊥School of Materials Science and Engineering, Gwangju Institute of Science and Technology (GIST) , Gwangju 500-712, Republic of Korea
| | - Ju-Young Byun
- Berkeley Sensor and Actuator Center, Department of Bioengineering, §Department of Electrical Engineering and Computer Science, Biophysics Graduate Program, University of California at Berkeley , Berkeley, California 94720, United States
- Department of Chemistry, School of Physics and Chemistry, ⊥School of Materials Science and Engineering, Gwangju Institute of Science and Technology (GIST) , Gwangju 500-712, Republic of Korea
| | - Jae Young Lee
- Berkeley Sensor and Actuator Center, Department of Bioengineering, §Department of Electrical Engineering and Computer Science, Biophysics Graduate Program, University of California at Berkeley , Berkeley, California 94720, United States
- Department of Chemistry, School of Physics and Chemistry, ⊥School of Materials Science and Engineering, Gwangju Institute of Science and Technology (GIST) , Gwangju 500-712, Republic of Korea
| | - Min-Gon Kim
- Berkeley Sensor and Actuator Center, Department of Bioengineering, §Department of Electrical Engineering and Computer Science, Biophysics Graduate Program, University of California at Berkeley , Berkeley, California 94720, United States
- Department of Chemistry, School of Physics and Chemistry, ⊥School of Materials Science and Engineering, Gwangju Institute of Science and Technology (GIST) , Gwangju 500-712, Republic of Korea
| | - Luke P Lee
- Berkeley Sensor and Actuator Center, Department of Bioengineering, §Department of Electrical Engineering and Computer Science, Biophysics Graduate Program, University of California at Berkeley , Berkeley, California 94720, United States
- Department of Chemistry, School of Physics and Chemistry, ⊥School of Materials Science and Engineering, Gwangju Institute of Science and Technology (GIST) , Gwangju 500-712, Republic of Korea
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182
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Wen S, Li M, Yang J, Mei X, Wu B, Liu X, Heng J, Qin D, Hou L, Xu W, Wang D. Rationally Controlled Synthesis of CdSe xTe 1-x Alloy Nanocrystals and Their Application in Efficient Graded Bandgap Solar Cells. Nanomaterials (Basel) 2017; 7:nano7110380. [PMID: 29117132 PMCID: PMC5707597 DOI: 10.3390/nano7110380] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/27/2017] [Revised: 11/01/2017] [Accepted: 11/05/2017] [Indexed: 11/25/2022]
Abstract
CdSexTe1−x semiconductor nanocrystals (NCs), being rod-shaped/irregular dot-shaped in morphology, have been fabricated via a simple hot-injection method. The NCs composition is well controlled through varying molar ratios of Se to Te precursors. Through changing the composition of the CdSexTe1−x NCs, the spectral absorption of the NC thin film between 570–800 nm is proved to be tunable. It is shown that the bandgap of homogeneously alloyed CdSexTe1−x active thin film is nonlinearly correlated with the different compositions, which is perceived as optical bowing. The solar cell devices based on CdSexTe1−x NCs with the structure of ITO/ZnO/CdSe/CdSexTe1−x/MoOx/Au and the graded bandgap ITO/ZnO/CdSe(w/o)/CdSexTe1−x/CdTe/MoOx/Au are systematically evaluated. It was found that the performance of solar cells degrades almost linearly with the increase of alloy NC film thickness with respect to ITO/ZnO/CdSe/CdSe0.2Te0.8/MoOx/Au. From another perspective, in terms of the graded bandgap structure of ITO/ZnO/CdSe/CdSexTe1−x/CdTe/MoOx/Au, the performance is improved in contrast with its single-junction analogues. The graded bandgap structure is proved to be efficient when absorbing spectrum and the solar cells fabricated under the structure of ITO/ZnO/CdSe0.8Te0.2/CdSe0.2Te0.8/CdTe/MoOx/Au indicate power conversion efficiency (PCE) of 6.37%, a value among the highest for solution-processed inversely-structured CdSexTe1−x NC solar cells. As the NC solar cells are solution-processed under environmental conditions, they are promising for fabricating solar cells at low cost, roll by roll and in large area.
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Affiliation(s)
- Shiya Wen
- School of Materials Science and Engineering, South China University of Technology, Guangzhou 510640, China.
| | - Miaozi Li
- School of Materials Science and Engineering, South China University of Technology, Guangzhou 510640, China.
| | - Junyu Yang
- Siyuan Laboratory, Guangzhou Key Laboratory of Vacuum Coating Technologies and New Energy Materials, Guangdong Provincial Key Laboratory of Optical Fiber Sensing and Communications, Department of Physics, Jinan University, Guangzhou 510632, China.
| | - Xianglin Mei
- School of Materials Science and Engineering, South China University of Technology, Guangzhou 510640, China.
| | - Bin Wu
- School of Materials Science and Engineering, South China University of Technology, Guangzhou 510640, China.
| | - Xiaolin Liu
- School of Materials Science and Engineering, South China University of Technology, Guangzhou 510640, China.
| | - Jingxuan Heng
- School of Materials Science and Engineering, South China University of Technology, Guangzhou 510640, China.
| | - Donghuan Qin
- School of Materials Science and Engineering, South China University of Technology, Guangzhou 510640, China.
- Institute of Polymer Optoelectronic Materials & Devices, State Key Laboratory of Luminescent Materials & Devices, South China University of Technology, Guangzhou 510640, China.
| | - Lintao Hou
- Siyuan Laboratory, Guangzhou Key Laboratory of Vacuum Coating Technologies and New Energy Materials, Guangdong Provincial Key Laboratory of Optical Fiber Sensing and Communications, Department of Physics, Jinan University, Guangzhou 510632, China.
| | - Wei Xu
- School of Materials Science and Engineering, South China University of Technology, Guangzhou 510640, China.
- Institute of Polymer Optoelectronic Materials & Devices, State Key Laboratory of Luminescent Materials & Devices, South China University of Technology, Guangzhou 510640, China.
| | - Dan Wang
- School of Materials Science and Engineering, South China University of Technology, Guangzhou 510640, China.
- Institute of Polymer Optoelectronic Materials & Devices, State Key Laboratory of Luminescent Materials & Devices, South China University of Technology, Guangzhou 510640, China.
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183
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Ghosh S, Soudackov AV, Hammes-Schiffer S. Role of Proton Diffusion in the Nonexponential Kinetics of Proton-Coupled Electron Transfer from Photoreduced ZnO Nanocrystals. ACS Nano 2017; 11:10295-10302. [PMID: 28925682 DOI: 10.1021/acsnano.7b05009] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Experiments have suggested that photoreduced ZnO nanocrystals transfer an electron and a proton to organic radicals through a concerted proton-coupled electron transfer (PCET) mechanism. The kinetics of this process was studied by monitoring the decay of the absorbance that reflects the concentration of electrons in the conduction bands of the nanocrystals. Interestingly, this absorbance exhibited nonexponential decay kinetics that could not be explained by heterogeneities of the nanoparticles or electron content. To determine if proton diffusion from inside the nanocrystal to reactive sites on the surface could lead to such nonexponential kinetics, herein this process is modeled using kinetic Monte Carlo simulations. These simulations provide the survival probability of a proton hopping among bulk, subsurface, and surface sites within the nanocrystal until it reaches a reactive surface site where it transfers to an organic radical. Using activation barriers predominantly obtained from periodic density functional theory, the simulations reproduce the nonexponential decay kinetics. This nonexponential behavior is found to arise from the broad distribution of lifetimes caused by different types of subsurface and surface sites. The longer lifetimes are associated with the proton becoming temporarily trapped in a subsurface site that does not have direct access to a reactive surface site due to capping ligands. These calculations suggest that movement of the protons rather than the electrons dominate the nonexponential kinetics of the PCET reaction. Thus, the impact of both bulk and surface properties of metal-oxide nanoparticles on proton conductivity should be considered when designing heterogeneous catalysts.
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Affiliation(s)
- Soumya Ghosh
- Department of Chemistry, 600 South Mathews Avenue, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States
| | - Alexander V Soudackov
- Department of Chemistry, 600 South Mathews Avenue, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States
| | - Sharon Hammes-Schiffer
- Department of Chemistry, 600 South Mathews Avenue, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States
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184
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Yin X, Shi M, Wu J, Pan YT, Gray DL, Bertke JA, Yang H. Quantitative Analysis of Different Formation Modes of Platinum Nanocrystals Controlled by Ligand Chemistry. Nano Lett 2017; 17:6146-6150. [PMID: 28873317 DOI: 10.1021/acs.nanolett.7b02751] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Well-defined metal nanocrystals play important roles in various fields, such as catalysis, medicine, and nanotechnology. They are often synthesized through kinetically controlled process in colloidal systems that contain metal precursors and surfactant molecules. The chemical functionality of surfactants as coordinating ligands to metal ions however remains a largely unsolved problem in this process. Understanding the metal-ligand complexation and its effect on formation kinetics at the molecular level is challenging but essential to the synthesis design of colloidal nanocrystals. Herein we report that spontaneous ligand replacement and anion exchange control the form of coordinated Pt-ligand intermediates in the system of platinum acetylacetonate [Pt(acac)2], primary aliphatic amine, and carboxylic acid ligands. The formed intermediates govern the formation mode of Pt nanocrystals, leading to either a pseudo two-step or a one-step mechanism by switching on or off an autocatalytic surface growth. This finding shows the importance of metal-ligand complexation at the prenucleation stage and represents a critical step forward for the designed synthesis of nanocrystal-based materials.
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Affiliation(s)
- Xi Yin
- Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign , 206 Roger Adams Laboratory, 600 South Matthews Avenue, Urbana, Illinois 61801, United States
| | - Miao Shi
- Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign , 206 Roger Adams Laboratory, 600 South Matthews Avenue, Urbana, Illinois 61801, United States
| | - Jianbo Wu
- Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign , 206 Roger Adams Laboratory, 600 South Matthews Avenue, Urbana, Illinois 61801, United States
| | - Yung-Tin Pan
- Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign , 206 Roger Adams Laboratory, 600 South Matthews Avenue, Urbana, Illinois 61801, United States
| | - Danielle L Gray
- George L. Clark X-ray Facility, University of Illinois at Urbana-Champaign , 505 South Matthews Avenue, Urbana, Illinois 61801, United States
| | - Jeffery A Bertke
- George L. Clark X-ray Facility, University of Illinois at Urbana-Champaign , 505 South Matthews Avenue, Urbana, Illinois 61801, United States
| | - Hong Yang
- Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign , 206 Roger Adams Laboratory, 600 South Matthews Avenue, Urbana, Illinois 61801, United States
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185
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Montanarella F, Altantzis T, Zanaga D, Rabouw FT, Bals S, Baesjou P, Vanmaekelbergh D, van Blaaderen A. Composite Supraparticles with Tunable Light Emission. ACS Nano 2017; 11:9136-9142. [PMID: 28787121 PMCID: PMC5618141 DOI: 10.1021/acsnano.7b03975] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2017] [Accepted: 08/08/2017] [Indexed: 05/20/2023]
Abstract
Robust luminophores emitting light with broadly tunable colors are desirable in many applications such as light-emitting diode (LED)-based lighting, displays, integrated optoelectronics and biology. Nanocrystalline quantum dots with multicolor emission, from core- and shell-localized excitons, as well as solid layers of mixed quantum dots that emit different colors have been proposed. Here, we report on colloidal supraparticles that are composed of three types of Cd(Se,ZnS) core/(Cd,Zn)S shell nanocrystals with emission in the red, green, and blue. The emission of the supraparticles can be varied from pure to composite colors over the entire visible region and fine-tuned into variable shades of white light by mixing the nanocrystals in controlled proportions. Our approach results in supraparticles with sizes spanning the colloidal domain and beyond that combine versatility and processability with a broad, stable, and tunable emission, promising applications in lighting devices and biological research.
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Affiliation(s)
- Federico Montanarella
- Condensed Matter and Interfaces and Soft Condensed Matter, Debye Institute
for
Nanomaterials Science, Utrecht University, P.O. Box 80000, 3508 TA Utrecht, The Netherlands
| | - Thomas Altantzis
- EMAT, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp, Belgium
| | - Daniele Zanaga
- EMAT, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp, Belgium
| | - Freddy T. Rabouw
- Condensed Matter and Interfaces and Soft Condensed Matter, Debye Institute
for
Nanomaterials Science, Utrecht University, P.O. Box 80000, 3508 TA Utrecht, The Netherlands
| | - Sara Bals
- EMAT, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp, Belgium
| | - Patrick Baesjou
- Condensed Matter and Interfaces and Soft Condensed Matter, Debye Institute
for
Nanomaterials Science, Utrecht University, P.O. Box 80000, 3508 TA Utrecht, The Netherlands
| | - Daniel Vanmaekelbergh
- Condensed Matter and Interfaces and Soft Condensed Matter, Debye Institute
for
Nanomaterials Science, Utrecht University, P.O. Box 80000, 3508 TA Utrecht, The Netherlands
- E-mail:
| | - Alfons van Blaaderen
- Condensed Matter and Interfaces and Soft Condensed Matter, Debye Institute
for
Nanomaterials Science, Utrecht University, P.O. Box 80000, 3508 TA Utrecht, The Netherlands
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186
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Wu L, Hu H, Xu Y, Jiang S, Chen M, Zhong Q, Yang D, Liu Q, Zhao Y, Sun B, Zhang Q, Yin Y. From Nonluminescent Cs 4PbX 6 (X = Cl, Br, I) Nanocrystals to Highly Luminescent CsPbX 3 Nanocrystals: Water-Triggered Transformation through a CsX-Stripping Mechanism. Nano Lett 2017; 17:5799-5804. [PMID: 28806517 DOI: 10.1021/acs.nanolett.7b02896] [Citation(s) in RCA: 180] [Impact Index Per Article: 25.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
We report a novel CsX-stripping mechanism that enables the efficient chemical transformation of nonluminescent Cs4PbX6 (X = Cl, Br, I) nanocrystals (NCs) to highly luminescent CsPbX3 NCs. During the transformation, Cs4PbX6 NCs dispersed in a nonpolar solvent are converted into CsPbX3 NCs by stripping CsX through an interfacial reaction with water in a different phase. This process takes advantage of the high solubility of CsX in water as well as the ionic nature and high ion diffusion property of Cs4PbX6 NCs, and produces monodisperse and air-stable CsPbX3 NCs with controllable halide composition, tunable emission wavelength covering the full visible range, narrow emission width, and high photoluminescent quantum yield (up to 75%). An additional advantage is that this is a clean synthesis as Cs4PbX6 NCs are converted into CsPbX3 NCs in the nonpolar phase while the byproduct of CsX is formed in water that could be easily separated from the organic phase. The as-prepared CsPbX3 NCs show enhanced stability against moisture because of the passivated surface. Our finding not only provides a new pathway for the preparation of highly luminescent CsPbX3 NCs but also adds insights into the chemical transformation behavior and stabilization mechanism of these emerging perovskite nanocrystals.
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Affiliation(s)
- Linzhong Wu
- Institute of Functional Nano and Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Soochow University , 199 Ren'ai Road, Suzhou, 215123, Jiangsu People's Republic of China
| | - Huicheng Hu
- Institute of Functional Nano and Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Soochow University , 199 Ren'ai Road, Suzhou, 215123, Jiangsu People's Republic of China
| | - Yong Xu
- Institute of Functional Nano and Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Soochow University , 199 Ren'ai Road, Suzhou, 215123, Jiangsu People's Republic of China
- Department of Chemistry, University of California, Riverside , Riverside, California 92521 United States
| | - Shu Jiang
- Institute of Functional Nano and Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Soochow University , 199 Ren'ai Road, Suzhou, 215123, Jiangsu People's Republic of China
| | - Min Chen
- Institute of Functional Nano and Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Soochow University , 199 Ren'ai Road, Suzhou, 215123, Jiangsu People's Republic of China
| | - Qixuan Zhong
- Institute of Functional Nano and Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Soochow University , 199 Ren'ai Road, Suzhou, 215123, Jiangsu People's Republic of China
| | - Di Yang
- Institute of Functional Nano and Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Soochow University , 199 Ren'ai Road, Suzhou, 215123, Jiangsu People's Republic of China
| | - Qipeng Liu
- Institute of Functional Nano and Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Soochow University , 199 Ren'ai Road, Suzhou, 215123, Jiangsu People's Republic of China
| | - Yun Zhao
- Institute of Functional Nano and Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Soochow University , 199 Ren'ai Road, Suzhou, 215123, Jiangsu People's Republic of China
| | - Baoquan Sun
- Institute of Functional Nano and Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Soochow University , 199 Ren'ai Road, Suzhou, 215123, Jiangsu People's Republic of China
| | - Qiao Zhang
- Institute of Functional Nano and Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Soochow University , 199 Ren'ai Road, Suzhou, 215123, Jiangsu People's Republic of China
| | - Yadong Yin
- Department of Chemistry, University of California, Riverside , Riverside, California 92521 United States
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187
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Ghosh S, Castillo-Lora J, Soudackov AV, Mayer JM, Hammes-Schiffer S. Theoretical Insights into Proton-Coupled Electron Transfer from a Photoreduced ZnO Nanocrystal to an Organic Radical. Nano Lett 2017; 17:5762-5767. [PMID: 28846428 DOI: 10.1021/acs.nanolett.7b02642] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Proton-coupled electron transfer (PCET) at metal-oxide nanoparticle interfaces plays a critical role in many photocatalytic reactions and energy conversion processes. Recent experimental studies have shown that photoreduced ZnO nanocrystals react by PCET with organic hydrogen atom acceptors such as the nitroxyl radical TEMPO. Herein, the interfacial PCET rate constant is calculated in the framework of vibronically nonadiabatic PCET theory, which treats the electrons and transferring proton quantum mechanically. The input quantities to the PCET rate constant, including the electronic couplings, are calculated with density functional theory. The computed interfacial PCET rate constant is consistent with the experimentally measured value for this system, providing validation for this PCET theory. In this model, the electron transfers from the conduction band of the ZnO nanocrystal to TEMPO concertedly with proton transfer from a surface oxygen of the ZnO nanocrystal to the oxygen of TEMPO. Moreover, the proton tunneling at the interface is gated by the relatively low-frequency proton donor-acceptor motion between the TEMPO radical and the ZnO nanocrystal. The ZnO nanocrystal and TEMPO are found to contribute similar amounts to the inner-sphere reorganization energy, implicating structural reorganization at the nanocrystal surface. These fundamental mechanistic insights may guide the design of metal-oxide nanocatalysts for a wide range of energy conversion processes.
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Affiliation(s)
- Soumya Ghosh
- Department of Chemistry, University of Illinois at Urbana-Champaign , 600 South Mathews Avenue, Urbana, Illinois 61801, United States
| | - Janelle Castillo-Lora
- Department of Chemistry, Yale University , New Haven, Connecticut 06520, United States
| | - Alexander V Soudackov
- Department of Chemistry, University of Illinois at Urbana-Champaign , 600 South Mathews Avenue, Urbana, Illinois 61801, United States
| | - James M Mayer
- Department of Chemistry, Yale University , New Haven, Connecticut 06520, United States
| | - Sharon Hammes-Schiffer
- Department of Chemistry, University of Illinois at Urbana-Champaign , 600 South Mathews Avenue, Urbana, Illinois 61801, United States
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188
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Zhang C, Zhang R, Li X, Chen W. PtNi Nanocrystals Supported on Hollow Carbon Spheres: Enhancing the Electrocatalytic Performance through High-Temperature Annealing and Electrochemical CO Stripping Treatments. ACS Appl Mater Interfaces 2017; 9:29623-29632. [PMID: 28813593 DOI: 10.1021/acsami.7b04489] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
PtNi nanoparticles have been proved to be a type of highly efficient electrocatalyst for the oxygen reduction reaction (ORR) among the Pt-based nanomaterials. However, how to improve the surface catalytic activity and stability of polymer-stabilized Pt-based nanocrystals is still a critical issue for their application in fuel cells. In this work, a one-step solvothermal process was used to synthesize PVP-stabilized PtNi nanocubes supported on hollow carbon spheres. With optimized metal precursor ratio (Pt/Ni = 1:1) and solvothermal temperature (130 °C), PtNi nanocrystals with uniform size and cubic shape can be synthesized and highly dispersed on hollow carbon spheres. To improve the electrocatalytic activity of the PtNi nanocrystals, the synthesized composite was treated by a heating annealing at 300 °C and a subsequent electrochemical CO stripping process. It was found that the two-step treatment can significantly enhance the catalytic activity of the PtNi nanocrystals for ORR with high durability. In addition, the prepared PtNi composite also showed higher catalytic activity and stability for methanol oxidation. The obtained peak current density on the present catalyst can reach 3.89 A/mgPt, which is 9 times as high as commercial Pt/C (0.43 A/mgPt). The present study not only demonstrates a general method to synthesize hollow carbon sphere-supported nanoparticle catalysts but also provides an efficient strategy to active the surface activity of nanoparticles.
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Affiliation(s)
- Chunmei Zhang
- State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences , Changchun 130022, Jilin China
- University of Chinese Academy of Sciences , Beijing 100039, China
| | - Ruizhong Zhang
- State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences , Changchun 130022, Jilin China
- University of Chinese Academy of Sciences , Beijing 100039, China
| | - Xiaokun Li
- State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences , Changchun 130022, Jilin China
| | - Wei Chen
- State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences , Changchun 130022, Jilin China
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189
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Zhang J, Yan J, Yang Q, Yan Y, Li S, Wang L, Li C, Lei B, Yang G, He W. Arginine-modified dual emission photoluminescent nanocrystals for bioimaging at subcellular resolution. J Biomater Appl 2017; 32:533-542. [PMID: 28799820 DOI: 10.1177/0885328217725203] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Bioimaging at a subcellular resolution to label cytoplasm and nucleus in living cell by just one photoluminescent nanoparticle has great application potential in bioresearch, preclinical diagnosis, screening, and image-guided therapy of life-threatening diseases. Herein, we report a novel arginine (Arg) functionalized ultra-small lanthanide oxyfluoride nanocrystals (LaOF) for simultaneously targeted imaging cell cytoplasm and nucleus. As-prepared Arg-modified PAA capped LaOF: 45%Ce, 15%Tb nanocrystals (LaOF:Ce,Tb@PAA@Arg) possessed high water dispersibility, ultra-small size (∼5.7 nm) and double emissions (green and red) with high quantum yield (40%). Such functionalized nanocrystals presented high cellular biocompatibility and were successfully used to label living cells with very high contrast. These functionalized nanocrystals also exhibited significantly higher photostability and brightness as compared to commercial dyes. Such the ultra-small size, high photostability and intensity, double emissions, excellent biocompatibility and targeted ability, make as-prepared functionalized nanocrystals particularly promising for cellular and subcellular bioimaging applications.
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Affiliation(s)
- Jun Zhang
- 1 Center for Physical Education, Xi'an Jiaotong University, Xi'an, China
| | - Jin Yan
- 2 State Key Laboratory for Mechanical Behavior of Materials, Frontier Institute of Science and Technology, Xi'an Jiaotong University, Xi'an, China
| | - Qingchen Yang
- 3 Key Laboratory of Biomedical Information Engineering of Ministry of Education, Center for Translational Medicine, School of Life Science and Technology and Frontier Institute of Science and Technology, Xi'an Jiaotong University, Xi'an, China
| | - Yuwei Yan
- 3 Key Laboratory of Biomedical Information Engineering of Ministry of Education, Center for Translational Medicine, School of Life Science and Technology and Frontier Institute of Science and Technology, Xi'an Jiaotong University, Xi'an, China
| | - Shichao Li
- 3 Key Laboratory of Biomedical Information Engineering of Ministry of Education, Center for Translational Medicine, School of Life Science and Technology and Frontier Institute of Science and Technology, Xi'an Jiaotong University, Xi'an, China
| | - Lijuan Wang
- 4 School of Science, Xi'an Jiaotong University, Xi'an, China
| | - Chenyu Li
- 4 School of Science, Xi'an Jiaotong University, Xi'an, China
| | - Bo Lei
- 2 State Key Laboratory for Mechanical Behavior of Materials, Frontier Institute of Science and Technology, Xi'an Jiaotong University, Xi'an, China
| | - Guang Yang
- 5 Department of Oncology, BenQ Medical Center, Nanjing Medical University, Nanjing, China
| | - Wangxiao He
- 3 Key Laboratory of Biomedical Information Engineering of Ministry of Education, Center for Translational Medicine, School of Life Science and Technology and Frontier Institute of Science and Technology, Xi'an Jiaotong University, Xi'an, China
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190
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Isarov M, Tan LZ, Bodnarchuk MI, Kovalenko MV, Rappe AM, Lifshitz E. Rashba Effect in a Single Colloidal CsPbBr 3 Perovskite Nanocrystal Detected by Magneto-Optical Measurements. Nano Lett 2017; 17:5020-5026. [PMID: 28657325 DOI: 10.1021/acs.nanolett.7b02248] [Citation(s) in RCA: 97] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
This study depicts the influence of the Rashba effect on the band-edge exciton processes in all-inorganic CsPbBr3 perovskite single colloidal nanocrystal (NC). The study is based on magneto-optical measurements carried out at cryogenic temperatures under various magnetic field strengths in which discrete excitonic transitions were detected by linearly and circularly polarized measurements. Interestingly, the experiments show a nonlinear energy splitting between polarized transitions versus magnetic field strength, indicating a crossover between a Rashba effect (at the lowest fields) to a Zeeman effect at fields above 4 T. We postulate that the Rashba effect emanates from a lattice distortion induced by the Cs+ motion degree of freedom or due to a surface effect in nanoscale NCs. The unusual magneto-optical properties shown here underscore the importance of the Rashba effect in the implementation of such perovskite materials in various optical and spin-based devices.
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Affiliation(s)
- Maya Isarov
- Schulich Faculty of Chemistry, Nancy and Stephen Grand Technion Energy Program, Russell Berrie Nanotechnology Institute, Solid State Institute, Technion , Haifa 3200003, Israel
| | - Liang Z Tan
- Department of Chemistry, University of Pennsylvania , Philadelphia, Pennsylvania 19104-6323, United States
| | - Maryna I Bodnarchuk
- Institute of Inorganic Chemistry, Department of Chemistry and Applied Biosciences, ETH Zürich , Vladimir Prelog Weg 1, CH-8093 Zürich, Switzerland
- Laboratory for Thin Films and Photovoltaics, Empa - Swiss Federal Laboratories for Materials Science and Technology , Überlandstrasse 129, CH-8600 Dübendorf, Switzerland
| | - Maksym V Kovalenko
- Institute of Inorganic Chemistry, Department of Chemistry and Applied Biosciences, ETH Zürich , Vladimir Prelog Weg 1, CH-8093 Zürich, Switzerland
- Laboratory for Thin Films and Photovoltaics, Empa - Swiss Federal Laboratories for Materials Science and Technology , Überlandstrasse 129, CH-8600 Dübendorf, Switzerland
| | - Andrew M Rappe
- Department of Chemistry, University of Pennsylvania , Philadelphia, Pennsylvania 19104-6323, United States
| | - Efrat Lifshitz
- Schulich Faculty of Chemistry, Nancy and Stephen Grand Technion Energy Program, Russell Berrie Nanotechnology Institute, Solid State Institute, Technion , Haifa 3200003, Israel
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191
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Greenberg BL, Robinson ZL, Reich KV, Gorynski C, Voigt BN, Francis LF, Shklovskii BI, Aydil ES, Kortshagen UR. ZnO Nanocrystal Networks Near the Insulator-Metal Transition: Tuning Contact Radius and Electron Density with Intense Pulsed Light. Nano Lett 2017; 17:4634-4642. [PMID: 28704060 DOI: 10.1021/acs.nanolett.7b01078] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Networks of ligand-free semiconductor nanocrystals (NCs) offer a valuable combination of high carrier mobility and optoelectronic properties tunable via quantum confinement. In principle, maximizing carrier mobility entails crossing the insulator-metal transition (IMT), where carriers become delocalized. A recent theoretical study predicted that this transition occurs at nρ3 ≈ 0.3, where n is the carrier density and ρ is the interparticle contact radius. In this work, we satisfy this criterion in networks of plasma-synthesized ZnO NCs by using intense pulsed light (IPL) annealing to tune n and ρ independently. IPL applied to as-deposited NCs increases ρ by inducing sintering, and IPL applied after the NCs are coated with Al2O3 by atomic layer deposition increases n by removing electron-trapping surface hydroxyls. This procedure does not substantially alter NC size or composition and is potentially applicable to a wide variety of nanomaterials. As we increase nρ3 to at least twice the predicted critical value, we observe conductivity scaling consistent with arrival at the critical region of a continuous quantum phase transition. This allows us to determine the critical behavior of the dielectric constant and electron localization length at the IMT. However, our samples remain on the insulating side of the critical region, which suggests that the critical value of nρ3 may in fact be significantly higher than 0.3.
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Affiliation(s)
| | | | - K V Reich
- Ioffe Institute , St Petersburg, 194021, Russia
| | - Claudia Gorynski
- Department of Mechanical and Process Engineering, University of Duisburg-Essen , Forsthausweg 2, 47057 Duisburg, Germany
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192
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Abstract
A number of bewildering paradoxes arise in the field of nanoparticle self-assembly: nominal low density superlattices, strong stability of low coordination sites, and a clear but imperfect correlation between lattice stability and the maximum of hard sphere packing, despite the fact that that nanocrystals themselves are, through their ligands, very much compressible. In this study, I show that by regarding nanocrystals as pseudotopological objects ("soft skyrmions"), it is possible to identify and classify the ligand textures that determine their bonding. These textures consist of interacting vortices, where the total vorticity defines a spontaneous valence (coordination). Furthermore, skyrmion interactions are governed by two simple assumptions, which lead to a set of selection rules for superlattice structure. Besides resolving all the above paradoxes, the predictions are completely supported by more than one hundred sixty experiments gathered from the literature, including a wide range of nanocrystal cores and ligands (saturated or unsaturated hydrocarbons, amines, polystyrene, etc.). How those results can be used for addressing more complex structures and guiding future experiments is also addressed.
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Affiliation(s)
- Alex Travesset
- Department of Physics and Astronomy and Ames Laboratory, Iowa State University , Ames, Iowa 50011, United States
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193
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Spoor FM, Tomić S, Houtepen AJ, Siebbeles LDA. Broadband Cooling Spectra of Hot Electrons and Holes in PbSe Quantum Dots. ACS Nano 2017; 11:6286-6294. [PMID: 28558190 PMCID: PMC5492216 DOI: 10.1021/acsnano.7b02506] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/2017] [Accepted: 05/30/2017] [Indexed: 05/22/2023]
Abstract
Understanding cooling of hot charge carriers in semiconductor quantum dots (QDs) is of fundamental interest and useful to enhance the performance of QDs in photovoltaics. We study electron and hole cooling dynamics in PbSe QDs up to high energies where carrier multiplication occurs. We characterize distinct cooling steps of hot electrons and holes and build up a broadband cooling spectrum for both charge carriers. Cooling of electrons is slower than of holes. At energies near the band gap we find cooling times between successive electronic energy levels in the order of 0.5 ps. We argue that here the large spacing between successive electronic energy levels requires cooling to occur by energy transfer to vibrational modes of ligand molecules or phonon modes associated with the QD surface. At high excess energy the energy loss rate of electrons is 1-5 eV/ps and exceeds 8 eV/ps for holes. Here charge carrier cooling can be understood in terms of emission of LO phonons with a higher density-of-states in the valence band than the conduction band. The complete mapping of the broadband cooling spectrum for both charge carriers in PbSe QDs is a big step toward understanding and controlling the cooling of hot charge carriers in colloidal QDs.
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Affiliation(s)
- Frank
C. M. Spoor
- Optoelectronic
Materials Section, Department of Chemical Engineering, Delft University of Technology, Van der Maasweg 9, 2629 HZ Delft, The Netherlands
| | - Stanko Tomić
- Joule
Physics Laboratory, School of Computing, Science and Engineering, University of Salford, Manchester M5 4WT, United Kingdom
| | - Arjan J. Houtepen
- Optoelectronic
Materials Section, Department of Chemical Engineering, Delft University of Technology, Van der Maasweg 9, 2629 HZ Delft, The Netherlands
| | - Laurens D. A. Siebbeles
- Optoelectronic
Materials Section, Department of Chemical Engineering, Delft University of Technology, Van der Maasweg 9, 2629 HZ Delft, The Netherlands
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194
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Qiao L, Fu Z, Li J, Ghosen J, Zeng M, Stebbins J, Prasad PN, Swihart MT. Standardizing Size- and Shape-Controlled Synthesis of Monodisperse Magnetite (Fe 3O 4) Nanocrystals by Identifying and Exploiting Effects of Organic Impurities. ACS Nano 2017; 11:6370-6381. [PMID: 28599110 DOI: 10.1021/acsnano.7b02752] [Citation(s) in RCA: 63] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Magnetite (Fe3O4) nanocrystals (MNCs) are among the most-studied magnetic nanomaterials, and many reports of solution-phase synthesis of monodisperse MNCs have been published. However, lack of reproducibility of MNC synthesis is a persistent problem, and the keys to producing monodisperse MNCs remain elusive. Here, we define and explore synthesis parameters in this system thoroughly to reveal their effects on the product MNCs. We demonstrate the essential role of benzaldehyde and benzyl benzoate produced by oxidation of benzyl ether, the solvent typically used for MNC synthesis, in producing monodisperse MNCs. This insight allowed us to develop stable formulas for producing monodisperse MNCs and propose a model to rationalize MNC size and shape evolution. Solvent polarity controls the MNC size, while short ligands shift the morphology from octahedral to cubic. We demonstrate preparation of specific assemblies with these MNCs. This standardized and reproducible synthesis of MNCs of well-controlled size, shape, and magnetic properties demonstrates a rational approach to stabilizing and expanding existing protocols for nanocrystal syntheses and may drive practical advances including enhanced MRI contrast, higher catalytic selectivity, and more accurate magnetic targeting.
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Affiliation(s)
| | | | - Ji Li
- MIIT Key Laboratory of Critical Materials Technology for New Energy Conversion and Storage, School of Chemistry and Chemical Engineering, Harbin Institute of Technology , Harbin, Heilongjiang 150001, China
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195
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Gilroy KD, Elnabawy AO, Yang TH, Roling LT, Howe J, Mavrikakis M, Xia Y. Thermal Stability of Metal Nanocrystals: An Investigation of the Surface and Bulk Reconstructions of Pd Concave Icosahedra. Nano Lett 2017; 17:3655-3661. [PMID: 28448153 DOI: 10.1021/acs.nanolett.7b00844] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Despite the remarkable success in controlling the synthesis of metal nanocrystals, it still remains a grand challenge to stabilize and preserve the shapes or internal structures of metastable kinetic products. In this work, we address this issue by systematically investigating the surface and bulk reconstructions experienced by a Pd concave icosahedron when subjected to heating up to 600 °C in vacuum. We used in situ high-resolution transmission electron microscopy to identify the equilibration pathways of this far-from-equilibrium structure. We were able to capture key structural transformations occurring during the thermal annealing process, which were mechanistically rationalized by implementing self-consistent plane-wave density functional theory (DFT) calculations. Specifically, the concave icosahedron was found to evolve into a regular icosahedron via surface reconstruction in the range of 200-400 °C, and then transform into a pseudospherical crystalline structure through bulk reconstruction when further heated to 600 °C. The mechanistic understanding may lead to the development of strategies for enhancing the thermal stability of metal nanocrystals.
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Affiliation(s)
- Kyle D Gilroy
- The Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University , Atlanta, Georgia 30332, United States
| | - Ahmed O Elnabawy
- Department of Chemical and Biological Engineering, University of Wisconsin-Madison , Madison, Wisconsin 53706, United States
| | - Tung-Han Yang
- The Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University , Atlanta, Georgia 30332, United States
| | - Luke T Roling
- Department of Chemical and Biological Engineering, University of Wisconsin-Madison , Madison, Wisconsin 53706, United States
| | - Jane Howe
- Hitachi High-Technologies Canada, Toronto, Ontario M9W 6A4, Canada
| | - Manos Mavrikakis
- Department of Chemical and Biological Engineering, University of Wisconsin-Madison , Madison, Wisconsin 53706, United States
| | - Younan Xia
- The Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University , Atlanta, Georgia 30332, United States
- School of Chemistry and Biochemistry, Georgia Institute of Technology , Atlanta, Georgia 30332, United States
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196
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Williams BA, Trejo ND, Wu A, Holgate CS, Francis LF, Aydil ES. Copper-Zinc-Tin-Sulfide Thin Films via Annealing of Ultrasonic Spray Deposited Nanocrystal Coatings. ACS Appl Mater Interfaces 2017; 9:18865-18871. [PMID: 28505419 DOI: 10.1021/acsami.7b04414] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Thin polycrystalline films of the solar absorber copper-zinc-tin-sulfide (CZTS) were formed by annealing coatings deposited on molybdenum-coated soda lime glass via ultrasonic spraying of aerosol droplets from colloidal CZTS nanocrystal dispersions. Production of uniform continuous nanocrystal coatings with ultrasonic spraying requires that the evaporation time is longer than the aerosol flight time from the spray nozzle to the substrate such that the aerosol droplets still have low enough viscosity to smooth the impact craters that form on the coating surface. In this work, evaporation was slowed by adding a high boiling point cosolvent, cyclohexanone, to toluene as the dispersing liquid. We analyzed, quantitatively, the effects of the solvent composition on the aerosol and coating drying dynamics using an aerosol evaporation model. Annealing coatings in sulfur vapor converts them into polycrystalline films with micrometer size grains, but the grains form continuous films only when Na is present during annealing to enhance grain growth. Continuous films are easier to form when the average nanocrystal size is 15 nm: using larger nanocrystals (e.g., 20 nm) sacrifices film continuity.
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Affiliation(s)
- Bryce A Williams
- Department of Chemical Engineering and Materials Science, University of Minnesota , Minneapolis, Minnesota 55455, United States
| | - Nancy D Trejo
- Department of Chemical Engineering and Materials Science, University of Minnesota , Minneapolis, Minnesota 55455, United States
| | - Albert Wu
- Department of Chemical Engineering and Materials Science, University of Minnesota , Minneapolis, Minnesota 55455, United States
| | - Collin S Holgate
- Department of Chemical Engineering and Materials Science, University of Minnesota , Minneapolis, Minnesota 55455, United States
| | - Lorraine F Francis
- Department of Chemical Engineering and Materials Science, University of Minnesota , Minneapolis, Minnesota 55455, United States
| | - Eray S Aydil
- Department of Chemical Engineering and Materials Science, University of Minnesota , Minneapolis, Minnesota 55455, United States
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197
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Abe S, Joos JJ, Martin LIDJ, Hens Z, Smet PF. Hybrid remote quantum dot/powder phosphor designs for display backlights. Light Sci Appl 2017; 6:e16271. [PMID: 30167259 PMCID: PMC6062237 DOI: 10.1038/lsa.2016.271] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2016] [Revised: 12/05/2016] [Accepted: 12/07/2016] [Indexed: 05/18/2023]
Abstract
Quantum dots are ideally suited for color conversion in light emitting diodes owing to their spectral tunability, high conversion efficiency and narrow emission bands. These properties are particularly important for display backlights; the highly saturated colors generated by quantum dots justify their higher production cost. Here, we demonstrate the benefits of a hybrid remote phosphor approach that combines a green-emitting europium-doped phosphor with red-emitting CdSe/CdS core/shell quantum dots. Different stacking geometries, including mixed and separate layers of both materials, are studied at the macroscopic and microscopic levels to identify the configuration that achieves maximum device efficiency while minimizing material usage. The influence of reabsorption, optical outcoupling and refractive index-matching between the layers is evaluated in detail with respect to device efficiency and cost. From the findings of this study, general guidelines are derived to optimize both the cost and efficiency of CdSe/CdS and other (potentially cadmium-free) quantum dot systems. When reabsorption of the green and/or red emission is significant compared to the absorption strength for the blue emission of the pumping light emitting diode, the hybrid remote phosphor approach becomes beneficial.
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Affiliation(s)
- Sofie Abe
- Department of Inorganic and Physical Chemistry, Ghent University, Gent, Belgium
- Department of Solid State Sciences, LumiLab, Ghent University, Gent, Belgium
- Center for Nano and Biophotonics, Ghent University, Gent, Belgium
| | - Jonas J Joos
- Department of Solid State Sciences, LumiLab, Ghent University, Gent, Belgium
- Center for Nano and Biophotonics, Ghent University, Gent, Belgium
| | - Lisa IDJ Martin
- Department of Solid State Sciences, LumiLab, Ghent University, Gent, Belgium
- Center for Nano and Biophotonics, Ghent University, Gent, Belgium
| | - Zeger Hens
- Department of Inorganic and Physical Chemistry, Ghent University, Gent, Belgium
- Center for Nano and Biophotonics, Ghent University, Gent, Belgium
| | - Philippe F Smet
- Department of Solid State Sciences, LumiLab, Ghent University, Gent, Belgium
- Center for Nano and Biophotonics, Ghent University, Gent, Belgium
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198
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Li M, Liu X, Wen S, Liu S, Heng J, Qin D, Hou L, Wu H, Xu W, Huang W. CdTe Nanocrystal Hetero-Junction Solar Cells with High Open Circuit Voltage Based on Sb-doped TiO₂ Electron Acceptor Materials. Nanomaterials (Basel) 2017; 7:E101. [PMID: 28467347 DOI: 10.3390/nano7050101] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/13/2017] [Revised: 04/27/2017] [Accepted: 04/28/2017] [Indexed: 12/04/2022]
Abstract
We propose Sb-doped TiO2 as electron acceptor material for depleted CdTe nanocrystal (NC) hetero-junction solar cells. Novel devices with the architecture of FTO/ZnO/Sb:TiO2/CdTe/Au based on CdTe NC and TiO2 precursor are fabricated by rational ambient solution process. By introducing TiO2 with dopant concentration, we are able to tailor the optoelectronic properties of NC solar cells. Our novel devices demonstrate a very high open circuit voltage of 0.74 V, which is the highest Voc reported for any CdTe NC based solar cells. The power conversion efficiency (PCE) of solar cells increases with the increase of Sb-doped content from 1% to 3%, then decreases almost linearly with further increase of Sb content due to the recombination effect. The champion device shows Jsc, Voc, FF, and PCE of 14.65 mA/cm2, 0.70 V, 34.44, and 3.53% respectively, which is prospective for solution processed NC solar cells with high Voc.
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199
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Li B, Bian K, Zhou X, Lu P, Liu S, Brener I, Sinclair M, Luk T, Schunk H, Alarid L, Clem PG, Wang Z, Fan H. Pressure compression of CdSe nanoparticles into luminescent nanowires. Sci Adv 2017; 3:e1602916. [PMID: 28508074 PMCID: PMC5419700 DOI: 10.1126/sciadv.1602916] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2016] [Accepted: 03/08/2017] [Indexed: 05/20/2023]
Abstract
Oriented attachment (OA) of synthetic nanocrystals is emerging as an effective means of fabricating low-dimensional nanoscale materials. However, OA relies on energetically favorable nanocrystal facets to grow nanostructured materials. Consequently, nanostructures synthesized through OA are generally limited to a specific crystal facet in their final morphology. We report our discovery that high-pressure compression can induce consolidation of spherical CdSe nanocrystal arrays, leading to unexpected one-dimensional semiconductor nanowires that do not exhibit the typical crystal facet. In particular, in situ high-pressure synchrotron x-ray scattering, optical spectroscopy, and high-resolution transmission electron microscopy characterizations indicate that by manipulating the coupling between nanocrystals through external pressure, a reversible change in nanocrystal assemblies and properties can be achieved at modest pressure. When pressure is increased above a threshold, these nanocrystals begin to contact one another and consolidate, irreversibly forming one-dimensional luminescent nanowires. High-fidelity molecular dynamics (MD) methods were used to calculate surface energies and simulate compression and coalescence mechanisms of CdSe nanocrystals. The MD results provide new insight into nanowire assembly dynamics and phase stability of nanocrystalline structures.
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Affiliation(s)
- Binsong Li
- Sandia National Laboratories, Albuquerque, NM 87185, USA
| | - Kaifu Bian
- Sandia National Laboratories, Albuquerque, NM 87185, USA
| | - Xiaowang Zhou
- Sandia National Laboratories, Albuquerque, NM 87185, USA
| | - Ping Lu
- Sandia National Laboratories, Albuquerque, NM 87185, USA
| | - Sheng Liu
- Sandia National Laboratories, Albuquerque, NM 87185, USA
| | - Igal Brener
- Sandia National Laboratories, Albuquerque, NM 87185, USA
| | | | - Ting Luk
- Sandia National Laboratories, Albuquerque, NM 87185, USA
| | - Hattie Schunk
- Sandia National Laboratories, Albuquerque, NM 87185, USA
| | - Leanne Alarid
- Sandia National Laboratories, Albuquerque, NM 87185, USA
| | - Paul G. Clem
- Sandia National Laboratories, Albuquerque, NM 87185, USA
| | - Zhongwu Wang
- Cornell High Energy Synchrotron Source, Cornell University, Ithaca, NY 14853, USA
| | - Hongyou Fan
- Sandia National Laboratories, Albuquerque, NM 87185, USA
- Department of Chemical and Biological Engineering, Center for Micro-Engineered Materials, University of New Mexico, Albuquerque, NM 87106, USA
- Corresponding author.
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200
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Treml BE, Savitzky BH, Tirmzi AM, DaSilva JC, Kourkoutis LF, Hanrath T. Successive Ionic Layer Absorption and Reaction for Postassembly Control over Inorganic Interdot Bonds in Long-Range Ordered Nanocrystal Films. ACS Appl Mater Interfaces 2017; 9:13500-13507. [PMID: 28368112 DOI: 10.1021/acsami.7b01588] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Epitaxially connected assemblies of nanocrystals (NCs) present an interesting new class of nanomaterial in which confinement of charge carriers is intermediate between that of a quantum dot and a quantum well. Despite impressive advances in the formation of high-fidelity assemblies, predicted collective properties have not yet emerged. A critical knowledge gap toward realizing these properties is the current lack of understanding of and control over the formation of epitaxial interdot bonds connecting the NCs within the assemblies. In this work we demonstrate successive ionic layer absorption and reaction (SILAR) to enhance the interdot bonding within the NC assembly. SILAR treatment improved the fraction of interdot bonds from 82% to 91% and increased their width from 3.1 to 4.0 nm. Absorption spectra and charge transport measurements indicate that the effect of postassembly growth on quantum confinement in this system depends on the composition of the SILAR shell material. Increased NC film conductance following SILAR processing indicates that building and strengthening interdot bonds lead to increased electronic coupling and doping in the assemblies. The postassembly film growth detailed here presents an opportunity to repair structural defects and to tailor the balance of quantum confinement and interdot coupling in epitaxially connected NC assemblies.
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Affiliation(s)
- Benjamin E Treml
- Department of Materials Science and Engineering, ‡Department of Physics, §Department of Chemistry and Chemical Biology, ∥School of Applied and Engineering Physics, ⊥Kavli Institute for Nanoscale Science, and #Robert Fredrick Smith School of Chemical and Biomolecular Engineering, Cornell University , Ithaca, New York 14853, United States
| | - Benjamin H Savitzky
- Department of Materials Science and Engineering, ‡Department of Physics, §Department of Chemistry and Chemical Biology, ∥School of Applied and Engineering Physics, ⊥Kavli Institute for Nanoscale Science, and #Robert Fredrick Smith School of Chemical and Biomolecular Engineering, Cornell University , Ithaca, New York 14853, United States
| | - Ali M Tirmzi
- Department of Materials Science and Engineering, ‡Department of Physics, §Department of Chemistry and Chemical Biology, ∥School of Applied and Engineering Physics, ⊥Kavli Institute for Nanoscale Science, and #Robert Fredrick Smith School of Chemical and Biomolecular Engineering, Cornell University , Ithaca, New York 14853, United States
| | - Jessica Cimada DaSilva
- Department of Materials Science and Engineering, ‡Department of Physics, §Department of Chemistry and Chemical Biology, ∥School of Applied and Engineering Physics, ⊥Kavli Institute for Nanoscale Science, and #Robert Fredrick Smith School of Chemical and Biomolecular Engineering, Cornell University , Ithaca, New York 14853, United States
| | - Lena F Kourkoutis
- Department of Materials Science and Engineering, ‡Department of Physics, §Department of Chemistry and Chemical Biology, ∥School of Applied and Engineering Physics, ⊥Kavli Institute for Nanoscale Science, and #Robert Fredrick Smith School of Chemical and Biomolecular Engineering, Cornell University , Ithaca, New York 14853, United States
| | - Tobias Hanrath
- Department of Materials Science and Engineering, ‡Department of Physics, §Department of Chemistry and Chemical Biology, ∥School of Applied and Engineering Physics, ⊥Kavli Institute for Nanoscale Science, and #Robert Fredrick Smith School of Chemical and Biomolecular Engineering, Cornell University , Ithaca, New York 14853, United States
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