1
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Shulenberger KE, Jilek MR, Sherman SJ, Hohman BT, Dukovic G. Electronic Structure and Excited State Dynamics of Cadmium Chalcogenide Nanorods. Chem Rev 2023; 123:3852-3903. [PMID: 36881852 DOI: 10.1021/acs.chemrev.2c00676] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/09/2023]
Abstract
The cylindrical quasi-one-dimensional shape of colloidal semiconductor nanorods (NRs) gives them unique electronic structure and optical properties. In addition to the band gap tunability common to nanocrystals, NRs have polarized light absorption and emission and high molar absorptivities. NR-shaped heterostructures feature control of electron and hole locations as well as light emission energy and efficiency. We comprehensively review the electronic structure and optical properties of Cd-chalcogenide NRs and NR heterostructures (e.g., CdSe/CdS dot-in-rods, CdSe/ZnS rod-in-rods), which have been widely investigated over the last two decades due in part to promising optoelectronic applications. We start by describing methods for synthesizing these colloidal NRs. We then detail the electronic structure of single-component and heterostructure NRs and follow with a discussion of light absorption and emission in these materials. Next, we describe the excited state dynamics of these NRs, including carrier cooling, carrier and exciton migration, radiative and nonradiative recombination, multiexciton generation and dynamics, and processes that involve trapped carriers. Finally, we describe charge transfer from photoexcited NRs and connect the dynamics of these processes with light-driven chemistry. We end with an outlook that highlights some of the outstanding questions about the excited state properties of Cd-chalcogenide NRs.
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Affiliation(s)
| | - Madison R Jilek
- Department of Chemistry, University of Colorado Boulder, Boulder, Colorado 80309, United States
| | - Skylar J Sherman
- Department of Chemistry, University of Colorado Boulder, Boulder, Colorado 80309, United States
| | - Benjamin T Hohman
- Department of Chemistry, University of Colorado Boulder, Boulder, Colorado 80309, United States
| | - Gordana Dukovic
- Department of Chemistry, University of Colorado Boulder, Boulder, Colorado 80309, United States.,Renewable and Sustainable Energy Institute (RASEI), University of Colorado Boulder, Boulder, Colorado 80309, United States.,Materials Science and Engineering, University of Colorado Boulder, Boulder, Colorado 80303, United States
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2
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Ben-Shahar Y, Stone D, Banin U. Rich Landscape of Colloidal Semiconductor-Metal Hybrid Nanostructures: Synthesis, Synergetic Characteristics, and Emerging Applications. Chem Rev 2023; 123:3790-3851. [PMID: 36735598 PMCID: PMC10103135 DOI: 10.1021/acs.chemrev.2c00770] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Nanochemistry provides powerful synthetic tools allowing one to combine different materials on a single nanostructure, thus unfolding numerous possibilities to tailor their properties toward diverse functionalities. Herein, we review the progress in the field of semiconductor-metal hybrid nanoparticles (HNPs) focusing on metal-chalcogenides-metal combined systems. The fundamental principles of their synthesis are discussed, leading to a myriad of possible hybrid architectures including Janus zero-dimensional quantum dot-based systems and anisotropic quasi 1D nanorods and quasi-2D platelets. The properties of HNPs are described with particular focus on emergent synergetic characteristics. Of these, the light-induced charge-separation effect across the semiconductor-metal nanojunction is of particular interest as a basis for the utilization of HNPs in photocatalytic applications. The extensive studies on the charge-separation behavior and its dependence on the HNPs structural characteristics, environmental and chemical conditions, and light excitation regime are surveyed. Combining the advanced synthetic control with the charge-separation effect has led to demonstration of various applications of HNPs in different fields. A particular promise lies in their functionality as photocatalysts for a variety of uses, including solar-to-fuel conversion, as a new type of photoinitiator for photopolymerization and 3D printing, and in novel chemical and biomedical uses.
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Affiliation(s)
- Yuval Ben-Shahar
- Department of Physical Chemistry, Israel Institute for Biological Research, P.O. Box 19, Ness Ziona74100, Israel
| | - David Stone
- The Institute of Chemistry and Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, Jerusalem91904, Israel
| | - Uri Banin
- The Institute of Chemistry and Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, Jerusalem91904, Israel
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3
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Faisal M, Rashed MA, Alhmami M, Harraz FA. Clean light oriented ultrafast Pt/Bi2S3 nanoflakes for the photocatalytic destruction of gemifloxacin mesylate drug and methylene blue. J Photochem Photobiol A Chem 2021. [DOI: 10.1016/j.jphotochem.2021.113288] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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4
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Solar-driven CO2 conversion over Co2+ doped 0D/2D TiO2/g-C3N4 heterostructure: Insights into the role of Co2+ and cocatalyst. J CO2 UTIL 2020. [DOI: 10.1016/j.jcou.2020.01.005] [Citation(s) in RCA: 40] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
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5
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Sandeep K, Manoj B, Thomas KG. Gold nanoparticle on semiconductor quantum dot: Do surface ligands influence Fermi level equilibration. J Chem Phys 2020; 152:044710. [PMID: 32007054 DOI: 10.1063/1.5138216] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Semiconductor-metal heterojunction nanostructures possess an ability to store electrons upon photoexcitation through Fermi level equilibration. The unique role of capping ligands in modulating the equilibration of Fermi level in CdSe-Au heteronanostructures is explored by taking alkyl thiols and alkyl amines as examples. Alkyl thiol having its highest occupied molecular orbital (HOMO) above the valence band of the heterojunction nanostructure inhibits the exciton recombination by scavenging the photogenerated hole. This leads to the elevation in the Fermi level of Au and equilibration with the conduction band of CdSe. The Fermi level equilibrated electrons are further transferred to an acceptor molecule such as methyl viologen, demonstrating the potential of heterojunction nanostructures capped with hole accepting ligands for charge transport application in photovoltaics. In contrast, alkyl amine being a non-hole acceptor ligand with its HOMO placed below its valence band promotes rapid Au mediated exciton recombination, limiting its usefulness in charge transport application. Thus, the energetics of ligands on heterojunction nanostructures plays a decisive role in Fermi level equilibration.
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Affiliation(s)
- K Sandeep
- School of Chemistry, Indian Institute of Science Education and Research Thiruvananthapuram (IISER-TVM), Vithura, Thiruvananthapuram 695 551, India
| | - B Manoj
- School of Chemistry, Indian Institute of Science Education and Research Thiruvananthapuram (IISER-TVM), Vithura, Thiruvananthapuram 695 551, India
| | - K George Thomas
- School of Chemistry, Indian Institute of Science Education and Research Thiruvananthapuram (IISER-TVM), Vithura, Thiruvananthapuram 695 551, India
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6
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Lian Z, Sakamoto M, Kobayashi Y, Tamai N, Ma J, Sakurai T, Seki S, Nakagawa T, Lai MW, Haruta M, Kurata H, Teranishi T. Anomalous Photoinduced Hole Transport in Type I Core/Mesoporous-Shell Nanocrystals for Efficient Photocatalytic H 2 Evolution. ACS NANO 2019; 13:8356-8363. [PMID: 31282648 DOI: 10.1021/acsnano.9b03826] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Controlling the carrier dynamics in a semiconductor nanoparticulate photocatalyst is the key to developing catalytic activity. Generally, type I band alignment is unsuitable for photocatalysts because the photoinduced carriers accumulate in the narrow bandgap semiconductor. To avoid the termination of reactions and/or photocorrosion of materials caused by carrier accumulation, it is common to employ type II band alignment for photoenergy conversion systems instead of type I. However, CdS/ZnS core/mesoporous-shell heterostructures show superior photocatalytic activity despite having type I band alignment that is generally unfavorable for photocatalytic reactions. Transient absorption spectroscopy and time-resolved microwave conductivity revealed efficient photoinduced hole transfer from the CdS phase to the ZnS phase. The defect-mediated hole transfer from the CdS to the ZnS phase resulted in long-lived charge separation (>2.4 ms) leading to high photocatalytic performance. This study provides insight into defect-mediated carrier transfer in nanoparticulate photocatalysts, which could be used as a guideline for the design of highly active and stable nanoparticulate photocatalysts.
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Affiliation(s)
- Zichao Lian
- Institute for Chemical Research , Kyoto University , Gokasho, Uji, Kyoto 611-0011 , Japan
| | - Masanori Sakamoto
- Institute for Chemical Research , Kyoto University , Gokasho, Uji, Kyoto 611-0011 , Japan
| | - Yoichi Kobayashi
- Department of Applied Chemistry, College of Life Sciences , Ritsumeikan University , 1-1-1 Noji-higashi , Kusatsu , Shiga 525-8577 , Japan
| | - Naoto Tamai
- Department of Chemistry, School of Science and Technology , Kwansei Gakuin University , 2-1 Gakuen , Sanda , Hyogo 669-1337 , Japan
| | - Jun Ma
- Department of Molecular Engineering, Graduate School of Engineering , Kyoto University , Nishikyo-ku , Kyoto 615-8510 , Japan
| | - Tsuneaki Sakurai
- Department of Molecular Engineering, Graduate School of Engineering , Kyoto University , Nishikyo-ku , Kyoto 615-8510 , Japan
| | - Shu Seki
- Department of Molecular Engineering, Graduate School of Engineering , Kyoto University , Nishikyo-ku , Kyoto 615-8510 , Japan
| | - Tatsuo Nakagawa
- Optical Instruments Division , Unisoku Co., Ltd. , Kasugano 2-4-3 , Hirakata , Osaka 573-0131 , Japan
| | - Ming-Wei Lai
- Institute for Chemical Research , Kyoto University , Gokasho, Uji, Kyoto 611-0011 , Japan
| | - Mitsutaka Haruta
- Institute for Chemical Research , Kyoto University , Gokasho, Uji, Kyoto 611-0011 , Japan
| | - Hiroki Kurata
- Institute for Chemical Research , Kyoto University , Gokasho, Uji, Kyoto 611-0011 , Japan
| | - Toshiharu Teranishi
- Institute for Chemical Research , Kyoto University , Gokasho, Uji, Kyoto 611-0011 , Japan
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7
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Ben-Shahar Y, Philbin JP, Scotognella F, Ganzer L, Cerullo G, Rabani E, Banin U. Charge Carrier Dynamics in Photocatalytic Hybrid Semiconductor-Metal Nanorods: Crossover from Auger Recombination to Charge Transfer. NANO LETTERS 2018; 18:5211-5216. [PMID: 29985622 DOI: 10.1021/acs.nanolett.8b02169] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Hybrid semiconductor-metal nanoparticles (HNPs) manifest unique, synergistic electronic and optical properties as a result of combining semiconductor and metal physics via a controlled interface. These structures can exhibit spatial charge separation across the semiconductor-metal junction upon light absorption, enabling their use as photocatalysts. The combination of the photocatalytic activity of the metal domain with the ability to generate and accommodate multiple excitons in the semiconducting domain can lead to improved photocatalytic performance because injecting multiple charge carriers into the active catalytic sites can increase the quantum yield. Herein, we show a significant metal domain size dependence of the charge carrier dynamics as well as the photocatalytic hydrogen generation efficiencies under nonlinear excitation conditions. An understanding of this size dependence allows one to control the charge carrier dynamics following the absorption of light. Using a model hybrid semiconductor-metal CdS-Au nanorod system and combining transient absorption and hydrogen evolution kinetics, we reveal faster and more efficient charge separation and transfer under multiexciton excitation conditions for large metal domains compared to small ones. Theoretical modeling uncovers a competition between the kinetics of Auger recombination and charge separation. A crossover in the dominant process from Auger recombination to charge separation as the metal domain size increases allows for effective multiexciton dissociation and harvesting in large metal domain HNPs. This was also found to lead to relative improvement of their photocatalytic activity under nonlinear excitation conditions.
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Affiliation(s)
- Yuval Ben-Shahar
- The Institute of Chemistry and Center for Nanoscience and Nanotechnology , The Hebrew University of Jerusalem , Jerusalem 91904 , Israel
| | - John P Philbin
- Department of Chemistry , University of California and Lawrence Berkeley National Laboratory , Berkeley , California 94720-1460 , United States
| | | | - Lucia Ganzer
- IFN-CNR, Dipartimento di Fisica , Politecnico di Milano , Milan 20133 , Italy
| | - Giulio Cerullo
- IFN-CNR, Dipartimento di Fisica , Politecnico di Milano , Milan 20133 , Italy
| | - Eran Rabani
- Department of Chemistry , University of California and Lawrence Berkeley National Laboratory , Berkeley , California 94720-1460 , United States
- The Sackler Institute for Computational Molecular and Materials Science , Tel Aviv University , Tel Aviv , Israel 69978
| | - Uri Banin
- The Institute of Chemistry and Center for Nanoscience and Nanotechnology , The Hebrew University of Jerusalem , Jerusalem 91904 , Israel
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8
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Ponseca CS, Chábera P, Uhlig J, Persson P, Sundström V. Ultrafast Electron Dynamics in Solar Energy Conversion. Chem Rev 2017; 117:10940-11024. [DOI: 10.1021/acs.chemrev.6b00807] [Citation(s) in RCA: 211] [Impact Index Per Article: 30.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Affiliation(s)
- Carlito S. Ponseca
- Division
of Chemical Physics, Chemical Center, and ‡Theoretical Chemistry Division,
Chemical Center, Lund University, Box 124, Lund SE-221 00, Sweden
| | - Pavel Chábera
- Division
of Chemical Physics, Chemical Center, and ‡Theoretical Chemistry Division,
Chemical Center, Lund University, Box 124, Lund SE-221 00, Sweden
| | - Jens Uhlig
- Division
of Chemical Physics, Chemical Center, and ‡Theoretical Chemistry Division,
Chemical Center, Lund University, Box 124, Lund SE-221 00, Sweden
| | - Petter Persson
- Division
of Chemical Physics, Chemical Center, and ‡Theoretical Chemistry Division,
Chemical Center, Lund University, Box 124, Lund SE-221 00, Sweden
| | - Villy Sundström
- Division
of Chemical Physics, Chemical Center, and ‡Theoretical Chemistry Division,
Chemical Center, Lund University, Box 124, Lund SE-221 00, Sweden
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9
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Beltran Madrigal J, Tellez-Limon R, Gardillou F, Barbier D, Geng W, Couteau C, Salas-Montiel R, Blaize S. Hybrid integrated optical waveguides in glass for enhanced visible photoluminescence of nanoemitters. APPLIED OPTICS 2016; 55:10263-10268. [PMID: 28059238 DOI: 10.1364/ao.55.010263] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Integrated optical devices able to control light-matter interactions on the nanoscale have attracted the attention of the scientific community in recent years. However, most of these devices are based on silicon waveguides, limiting their use for telecommunication wavelengths. In this contribution, we propose an integrated device that operates with light in the visible spectrum. The proposed device is a hybrid structure consisting of a high-refractive-index layer placed on top of an ion-exchanged glass waveguide. We demonstrate that this hybrid structure serves as an efficient light coupler for the excitation of nanoemitters. The numerical and experimental results show that the device can enhance the electromagnetic field confinement up to 11 times, allowing a higher photoluminescence signal from nanocrystals placed on its surface. The designed device opens new perspectives in the generation of new optical devices suitable for quantum information or for optical sensing.
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10
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Ben-Shahar Y, Banin U. Hybrid Semiconductor–Metal Nanorods as Photocatalysts. Top Curr Chem (Cham) 2016; 374:54. [DOI: 10.1007/s41061-016-0052-0] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2016] [Accepted: 07/07/2016] [Indexed: 11/30/2022]
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11
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Jin F, Zheng ML, Liu ZH, Fan YM, Xu K, Zhao ZS, Duan XM. Layer-by-layer assembled PMMA-SH/CdSe–Au nanocomposite thin films and the optical limiting property. RSC Adv 2016. [DOI: 10.1039/c6ra02893d] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
We demonstrate layer-by-layer assembly of PMMA-SH/CdSe–Au nanocomposite thin films with good transparency, thermal stability and optical liming property, which provide potential uses in laser protective devices.
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Affiliation(s)
- Feng Jin
- Laboratory of Organic Nanophotonics and Laboratory of Bio-Inspired Smart Interface Science
- Technical Institute of Physics and Chemistry
- Chinese Academy of Sciences
- Beijing
- P. R. China
| | - Mei-Ling Zheng
- Laboratory of Organic Nanophotonics and Laboratory of Bio-Inspired Smart Interface Science
- Technical Institute of Physics and Chemistry
- Chinese Academy of Sciences
- Beijing
- P. R. China
| | - Zheng-Hui Liu
- Suzhou Institute of Nano-Tech and Nano-Bionics
- Chinese Academy of Sciences
- Dushu Lake Higher Education Town
- Suzhou
- P. R. China
| | - Yi-Ming Fan
- Suzhou Institute of Nano-Tech and Nano-Bionics
- Chinese Academy of Sciences
- Dushu Lake Higher Education Town
- Suzhou
- P. R. China
| | - Ke Xu
- Suzhou Institute of Nano-Tech and Nano-Bionics
- Chinese Academy of Sciences
- Dushu Lake Higher Education Town
- Suzhou
- P. R. China
| | - Zhen-Sheng Zhao
- Laboratory of Organic Nanophotonics and Laboratory of Bio-Inspired Smart Interface Science
- Technical Institute of Physics and Chemistry
- Chinese Academy of Sciences
- Beijing
- P. R. China
| | - Xuan-Ming Duan
- Laboratory of Organic Nanophotonics and Laboratory of Bio-Inspired Smart Interface Science
- Technical Institute of Physics and Chemistry
- Chinese Academy of Sciences
- Beijing
- P. R. China
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12
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Jia K, Yuan L, Zhou X, Pan L, Wang P, Chen W, Liu X. One-pot synthesis of Au/Ag bimetallic nanoparticles to modulate the emission of CdSe/CdS quantum dots. RSC Adv 2015. [DOI: 10.1039/c5ra08933f] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Fluorescent emission of CdSe/CdS nanocrystals in colloid solution can be effectively modulated by Au/Ag bimetallic nanoparticles.
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Affiliation(s)
- Kun Jia
- Research Branch of Advanced Functional Materials
- High Temperature Resistant Polymer and Composites Key Laboratory of Sichuan Province
- School of Microelectronics and Solid-State Electronics
- University of Electronic Science and Technology of China
- Chengdu
| | - Liting Yuan
- Research Branch of Advanced Functional Materials
- High Temperature Resistant Polymer and Composites Key Laboratory of Sichuan Province
- School of Microelectronics and Solid-State Electronics
- University of Electronic Science and Technology of China
- Chengdu
| | - Xuefei Zhou
- Research Branch of Advanced Functional Materials
- High Temperature Resistant Polymer and Composites Key Laboratory of Sichuan Province
- School of Microelectronics and Solid-State Electronics
- University of Electronic Science and Technology of China
- Chengdu
| | - Lin Pan
- Research Branch of Advanced Functional Materials
- High Temperature Resistant Polymer and Composites Key Laboratory of Sichuan Province
- School of Microelectronics and Solid-State Electronics
- University of Electronic Science and Technology of China
- Chengdu
| | - Pan Wang
- Research Branch of Advanced Functional Materials
- High Temperature Resistant Polymer and Composites Key Laboratory of Sichuan Province
- School of Microelectronics and Solid-State Electronics
- University of Electronic Science and Technology of China
- Chengdu
| | - Wenjin Chen
- School of Resources and Environment
- University of Electronic Science and Technology of China
- Chengdu
- China
| | - Xiaobo Liu
- Research Branch of Advanced Functional Materials
- High Temperature Resistant Polymer and Composites Key Laboratory of Sichuan Province
- School of Microelectronics and Solid-State Electronics
- University of Electronic Science and Technology of China
- Chengdu
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13
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Soni U, Tripathy P, Sapra S. Photocatalysis from Fluorescence-Quenched CdSe/Au Nanoheterostructures: A Size-Dependent Study. J Phys Chem Lett 2014; 5:1909-1916. [PMID: 26273872 DOI: 10.1021/jz5006863] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We report a systematic study of the electron-transfer process from CdSe quantum dots (QDs) to the Au tips as a function of the QD diameter and also the size of the Au-tip. For Au-tips smaller than ∼3 nm, that is, when they are still not metallic, a reduction in PL behavior is observed as the excited electrons are transferred from the QD-conduction band to Au, with quenching being higher for larger tips and smaller QDs. A combination of steady state and time-resolved studies establish the mechanism of charge transfer that is further confirmed by dye-degradation studies, showing the possibility of ambient day light photocatalysis.
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Affiliation(s)
- Udit Soni
- Department of Chemistry, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
| | - Puspanjali Tripathy
- Department of Chemistry, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
| | - Sameer Sapra
- Department of Chemistry, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
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15
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Photocatalytic Au-Bi2S3Heteronanostructures. Angew Chem Int Ed Engl 2014; 53:6743-6. [DOI: 10.1002/anie.201402709] [Citation(s) in RCA: 127] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2014] [Revised: 04/07/2014] [Indexed: 11/07/2022]
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16
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Yan K, Zhang L, Kuang Q, Wei Z, Yi Y, Wang J, Yang S. Solution-processed, barrier-confined, and 1D nanostructure supported quasi-quantum well with large photoluminescence enhancement. ACS NANO 2014; 8:3771-3780. [PMID: 24580094 DOI: 10.1021/nn500465w] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Planar substrate supported semiconductor quantum well (QW) structures are not amenable to manipulation in miniature devices, while free-standing QW nanostructures, e.g., ultrathin nanosheets and nanoribbons, suffer from mechanical and environmental instability. Therefore, it is tempting to fashion high-quality QW structures on anisotropic and mechanically robust supporting nanostructures such as nanowires and nanoplates. Herein, we report a solution quasi-heteroepitaxial route for growing a barrier-confined quasi-QW structure (ZnSe/CdSe/ZnSe) on the supporting arms of ZnO nanotetrapods, which have a 1D nanowire structure, through the combination of ion exchange and successive deposition assembly. This resulted in highly crystalline and highly oriented quasi-QWs along the whole axial direction of the arms of the nanotetrapod because a transition buffer layer (Zn(x)Cd(1-x)Se) was formed and in turn reduced the lattice mismatch and surface defects. Significantly, such a barrier-confined QW emits excitonic light ∼17 times stronger than the heterojunction (HJ)-type structure (ZnSe/CdSe, HJ) at the single-particle level. Time-resolved photoluminescence from ensemble QWs exhibits a lifetime of 10 ns, contrasting sharply with ∼300 ps for the control HJ sample. Single-particle PL and Raman spectra suggest that the barrier layer of QW has completely removed the surface trap states on the HJ and restored or upgraded the photoelectric properties of the semiconductor layer. Therefore, this deliberate heteroepitaxial growth protocol on the supporting nanotetrapod has realized a several micrometer long QW structure with high mechanical robustness and high photoelectric quality. We envision that such QWs integrated on 1D nanostructures will largely improve the performance of solar cells and bioprobes, among others.
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Affiliation(s)
- Keyou Yan
- Nano Science and Technology Program, Department of Chemistry, and ‡Department of Physics, William Mong Institute of Nano Science and Technology, The Hong Kong University of Science and Technology , Clear Water Bay, Kowloon, Hong Kong
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17
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Lambright S, Butaeva E, Razgoniaeva N, Hopkins T, Smith B, Perera D, Corbin J, Khon E, Thomas R, Moroz P, Mereshchenko A, Tarnovsky A, Zamkov M. Enhanced lifetime of excitons in nonepitaxial Au/CdS core/shell nanocrystals. ACS NANO 2014; 8:352-61. [PMID: 24325605 DOI: 10.1021/nn404264w] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
The ability of metal nanoparticles to capture light through plasmon excitations offers an opportunity for enhancing the optical absorption of plasmon-coupled semiconductor materials via energy transfer. This process, however, requires that the semiconductor component is electrically insulated to prevent a "backward" charge flow into metal and interfacial states, which causes a premature dissociation of excitons. Here we demonstrate that such an energy exchange can be achieved on the nanoscale by using nonepitaxial Au/CdS core/shell nanocomposites. These materials are fabricated via a multistep cation exchange reaction, which decouples metal and semiconductor phases leading to fewer interfacial defects. Ultrafast transient absorption measurements confirm that the lifetime of excitons in the CdS shell (τ ≈ 300 ps) is much longer than lifetimes of excitons in conventional, reduction-grown Au/CdS heteronanostructures. As a result, the energy of metal nanoparticles can be efficiently utilized by the semiconductor component without undergoing significant nonradiative energy losses, an important property for catalytic or photovoltaic applications. The reduced rate of exciton dissociation in the CdS domain of Au/CdS nanocomposites was attributed to the nonepitaxial nature of Au/CdS interfaces associated with low defect density and a high potential barrier of the interstitial phase.
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Affiliation(s)
- Scott Lambright
- The Center for Photochemical Sciences, ‡Department of Chemistry, and §Department of Physics, Bowling Green State University , Bowling Green, Ohio 43403, United States
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