1
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Fu W, Yin J, Cao H, Zhou Z, Zhang J, Fu J, Warner JH, Wang C, Jia X, Greaves GN, Cheetham AK. Non-Blinking Luminescence from Charged Single Graphene Quantum Dots. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2023; 35:e2304074. [PMID: 37395476 DOI: 10.1002/adma.202304074] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/01/2023] [Revised: 06/24/2023] [Accepted: 06/26/2023] [Indexed: 07/04/2023]
Abstract
Photoluminescence blinking behavior from single quantum dots under steady illumination is an important but controversial topic. Its occurrence has impeded the use of single quantum dots in bioimaging. Different mechanisms have been proposed to account for it, although controversial, the most important of which is the non-radiative Auger recombination mechanism whereby photocharging of quantum dots can lead to the blinking phenomenon. Here, the singly charged trion, which maintains photon emission, including radiative recombination and non-radiative Auger recombination, leads to fluorescence non-blinking which is observed in photocharged single graphene quantum dots (GQDs). This phenomenon can be explained in terms of different energy levels in the GQDs, caused by various oxygen-containing functional groups in the single GQDs. The suppressed blinking is due to the filling of trap sites owing to a Coulomb blockade. These results provide a profound understanding of the special optical properties of GQDs, affording a reference for further in-depth research.
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Affiliation(s)
- Wei Fu
- Department of Chemistry, Tsinghua University, Beijing, 100084, China
| | - Jiefu Yin
- Department of Chemistry, Tsinghua University, Beijing, 100084, China
| | - Huaqiang Cao
- Department of Chemistry, Tsinghua University, Beijing, 100084, China
| | - Zhongfu Zhou
- State Key Laboratory of Advanced Special Steel, Shanghai Key Laboratory of Advanced Ferrometallurgy, Shanghai University, Shanghai, 200072, China
| | - Junying Zhang
- School of Physics, Beihang University, Beijing, 100191, China
| | - Jingjing Fu
- School of Medicine, Tsinghua University, Beijing, 100084, China
| | - Jamie H Warner
- Department of Mechanical Engineering, The University of Texas at Austin, 204 East Dean Keeton Street, Austin, TX, 78712, USA
| | - Cheng Wang
- Department of Chemistry, Tsinghua University, Beijing, 100084, China
| | - Xiaofang Jia
- School of Physics, Beihang University, Beijing, 100191, China
| | - G Neville Greaves
- Department of Physics, Aberystwyth University, Aberystwyth, SY23 3BZ, UK
- Department of Materials Science and Metallurgy, The University of Cambridge, Cambridge, CB3 0FS, UK
| | - Anthony K Cheetham
- Department of Materials Science and Metallurgy, The University of Cambridge, Cambridge, CB3 0FS, UK
- Materials Research Laboratory, University of California, Santa Barbara, CA, 93106, USA
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2
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Khabibrakhmanov AI, Sorokin PB. Electronic properties of graphene oxide: nanoroads towards novel applications. NANOSCALE 2022; 14:4131-4144. [PMID: 35175269 DOI: 10.1039/d2nr00251e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
In this work, we suggest an approach to manipulate the electronic properties of graphene oxide in a controllable manner. We study graphene nanoroads paved inside graphene oxide using density functional calculations. We show that this patterning allows transforming an insulator, graphene oxide, into a semiconductor or metal depending on the orientation of the nanoroads and their magnetic state. As a semiconductor, patterned graphene oxide is characterized by notably low effective masses of charge carriers. Additionally, we demonstrate the possibility to force the transition from a semiconducting to a half-metallic state in a controllable manner, by application of an external electric field. We believe that this remarkable opportunity to combine and control the electronic and magnetic properties of a material within a single sheet of graphene oxide paves the way towards new applications of graphene-oxide-based devices in 2D optoelectronics and spintronics.
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Affiliation(s)
- Almaz I Khabibrakhmanov
- National University of Science and Technology MISIS, 4 Leninskiy prospekt, Moscow, 119049, Russian Federation.
- Moscow Institute of Physics and Technology (National Research University), 9 Institutskiy per., Dolgoprudny, Moscow Region, 141701, Russian Federation
- Department of Physics and Materials Science, University of Luxembourg, L-1511 Luxembourg City, Luxembourg
| | - Pavel B Sorokin
- National University of Science and Technology MISIS, 4 Leninskiy prospekt, Moscow, 119049, Russian Federation.
- Moscow Institute of Physics and Technology (National Research University), 9 Institutskiy per., Dolgoprudny, Moscow Region, 141701, Russian Federation
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3
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Zheng SW, Wang L, Wang HY, Xu CY, Luo Y, Sun HB. Observation of quantum-confined exciton states in monolayer WS 2 quantum dots by ultrafast spectroscopy. NANOSCALE 2021; 13:17093-17100. [PMID: 34623366 DOI: 10.1039/d1nr04868f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Monolayer transition metal dichalcogenide quantum dots (TMDC QDs) could exhibit unique photophysical properties, because of both lateral quantum confinement effect and edge effect. However, there is little fundamental study on the quantum-confined exciton dynamics in monolayer TMDC QDs, to date. Here, by selective excitations of monolayer WS2 QDs in broadband transient absorption (TA) spectroscopy experiments, the excitation-wavelength-dependent ground state bleaching signals corresponding to the quantum-confined exciton states are directly observed. Compared to the time-resolved photophysical properties of WS2 nanosheets, the selected monolayer WS2 QDs only show one ground state bleaching peak with larger initial values for the linear polarization anisotropy of band-edge excitons, probably due to the expired spin-orbit coupling. This suggests a complete change of the band structure for monolayer WS2 QDs. In the femtosecond time-resolved circular polarization anisotropy experiments, a valley depolarization time of ∼100 fs is observed for WS2 nanosheets at room temperature, which is not observed for monolayer WS2 QDs. Our findings suggest a strong state-mixing of band-edge valley excitons responsible for the large linear polarization in monolayer WS2 QDs, which could be helpful for understanding the exciton relaxation mechanisms in colloidal monolayer TMDC QDs.
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Affiliation(s)
- Shu-Wen Zheng
- State Key Laboratory of Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, 2699 Qianjin Street, Changchun 130012, China.
| | - Lei Wang
- State Key Laboratory of Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, 2699 Qianjin Street, Changchun 130012, China.
| | - Hai-Yu Wang
- State Key Laboratory of Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, 2699 Qianjin Street, Changchun 130012, China.
| | - Chen-Yu Xu
- State Key Laboratory of Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, 2699 Qianjin Street, Changchun 130012, China.
| | - Yang Luo
- Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033, China
| | - Hong-Bo Sun
- State Key Laboratory of Precision Measurement Technology and Instruments, Department of Precision Instrument, Tsinghua University, Haidian, Beijing 100084, China
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4
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Mondal S, Ghorai N, Bhunia S, Ghosh HN, Amdursky N. Long-range light-modulated charge transport across the molecular heterostructure doped protein biopolymers. Chem Sci 2021; 12:8731-8739. [PMID: 34257872 PMCID: PMC8246076 DOI: 10.1039/d1sc00487e] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Accepted: 05/17/2021] [Indexed: 01/12/2023] Open
Abstract
Biological electron transfer (ET) across proteins is ubiquitous, such as the notable photosynthesis example, where light-induced charge separation takes place within the reaction center, followed by sequential ET via intramolecular cofactors within the protein. Far from biology, carbon dots (C-Dots) with their unique optoelectronic properties can be considered as game-changers for next-generation advanced technologies. Here, we use C-Dots for making heterostructure (HS) configurations by conjugating them to a natural ET mediator, the hemin molecule, thus making an electron donor-acceptor system. We show by transient absorption and emission spectroscopy that the rapid intramolecular charge separation happens following light excitation, which can be ascribed to an ultrafast electron and hole transfer (HT) from the C-Dot donor to the hemin acceptor. Upon integrating the HS into a protein matrix, we show that this HT within the HS configuration is 3.3 times faster compared to the same process in solution, indicating the active role of the protein in supporting the rapid light-induced long-range intermolecular charge separation. We further use impedance, electrochemical, and transient photocurrent measurements to show that the light-induced transient charge separation results in an enhanced ET and HT efficiency across the protein biopolymer. The charge conduction across our protein biopolymers, reaching nearly 0.01 S cm-1, along with the simplicity and low-cost of their formation promotes their use in a variety of optoelectronic devices, such as artificial photosynthesis, photo-responsive protonic-electronic transistors, and photodetectors.
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Affiliation(s)
- Somen Mondal
- Schulich Faculty of Chemistry, Technion - Israel Institute of Technology Haifa 3200003 Israel
- Institute of Chemical Technology, Mumbai, Marathwada Campus Jalna Maharashtra 431 203 India
| | - Nandan Ghorai
- Institute of Nano Science and Technology Mohali Punjab 160064 India
| | - Soumyadip Bhunia
- Indian Institute of Science Education and Research (IISER) Kolkata Mohanpur West Bengal 741246 India
| | - Hirendra N Ghosh
- Institute of Nano Science and Technology Mohali Punjab 160064 India
| | - Nadav Amdursky
- Schulich Faculty of Chemistry, Technion - Israel Institute of Technology Haifa 3200003 Israel
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5
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Tsujiguchi T, Kawabe Y, Jeong S, Ohto T, Kukunuri S, Kuramochi H, Takahashi Y, Nishiuchi T, Masuda H, Wakisaka M, Hu K, Elumalai G, Fujita JI, Ito Y. Acceleration of Electrochemical CO2 Reduction to Formate at the Sn/Reduced Graphene Oxide Interface. ACS Catal 2021. [DOI: 10.1021/acscatal.0c04887] [Citation(s) in RCA: 44] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Affiliation(s)
- Takuya Tsujiguchi
- Faculty of Mechanical Engineering, Institute of Science and Engineering, Kanazawa University, Kanazawa 920-1192, Japan
| | - Yusuke Kawabe
- Division of Electrical Engineering and Computer Science, Kanazawa University, Kanazawa 920-1192, Japan
| | - Samuel Jeong
- Institute of Applied Physics, Graduate School of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba 305-8571, Japan
| | - Tatsuhiko Ohto
- Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama, Toyonaka 560-8531, Japan
| | - Suresh Kukunuri
- Institute of Applied Physics, Graduate School of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba 305-8571, Japan
| | - Hirotaka Kuramochi
- Institute of Applied Physics, Graduate School of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba 305-8571, Japan
| | - Yasufumi Takahashi
- WPI Nano Life Science Institute (NanoLSI, WPI), Kanazawa University, Kakuma-machi, Kanazawa, Ishikawa 920-1192, Japan
- PRESTO, Japan Science and Technology Agency, Saitama 332-0012, Japan
| | - Tomohiko Nishiuchi
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan
| | - Hideki Masuda
- Institute of Applied Physics, Graduate School of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba 305-8571, Japan
| | - Mitsuru Wakisaka
- Graduate School of Engineering, Toyama Prefectural University, 5180 Kurokawa, Imizu, Toyama 939-0398, Japan
| | - Kailong Hu
- Institute of Applied Physics, Graduate School of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba 305-8571, Japan
| | - Ganesan Elumalai
- Institute of Applied Physics, Graduate School of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba 305-8571, Japan
| | - Jun-ichi Fujita
- Institute of Applied Physics, Graduate School of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba 305-8571, Japan
| | - Yoshikazu Ito
- Institute of Applied Physics, Graduate School of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba 305-8571, Japan
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6
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Lee BH, Hasan MT, Lichthardt D, Gonzalez-Rodriguez R, Naumov AV. Manganese-nitrogen and gadolinium-nitrogen Co-doped graphene quantum dots as bimodal magnetic resonance and fluorescence imaging nanoprobes. NANOTECHNOLOGY 2021; 32:095103. [PMID: 33126228 DOI: 10.1088/1361-6528/abc642] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Graphene quantum dots (GQDs) are unique derivatives of graphene that show promise in multiple biomedical applications as biosensors, bioimaging agents, and drug/gene delivery vehicles. Their ease in functionalization, biocompatibility, and intrinsic fluorescence enable those modalities. However, GQDs lack deep tissue magnetic resonance imaging (MRI) capabilities desirable for diagnostics. Considering that the drawbacks of MRI contrast agent toxicity are still poorly addressed, we develop novel Mn2+ or Gd3+ doped nitrogen-containing graphene quantum dots (NGQDs) to equip the GQDs with MRI capabilities and at the same time render contrast agents biocompatible. Water-soluble biocompatible Mn-NGQDs and Gd-NGQDs synthesized via single-step microwave-assisted scalable hydrothermal reaction enable dual MRI and fluorescence modalities. These quasi-spherical 3.9-6.6 nm average-sized structures possess highly crystalline graphitic lattice structure with 0.24 and 0.53 atomic % for Mn2+ and Gd3+ doping. This structure ensures high in vitro biocompatibility of up to 1.3 mg ml-1 and 1.5 mg ml-1 for Mn-NGQDs and Gd-NGQDs, respectively, and effective internalization in HEK-293 cells traced by intrinsic NGQD fluorescence. As MRI contrast agents with considerably low Gd and Mn content, Mn-NGQDs exhibit substantial transverse/longitudinal relaxivity (r 2/r 1) ratios of 11.190, showing potential as dual-mode longitudinal or transverse relaxation time (T 1 or T 2) contrast agents, while Gd-NGQDs possess r 2/r 1 of 1.148 with high r 1 of 9.546 mM-1 s-1 compared to commercial contrast agents, suggesting their potential as T1 contrast agents. Compared to other nanoplatforms, these novel Mn2+ and Gd3+ doped NGQDs not only provide scalable biocompatible alternatives as T1/T2 and T1 contrast agents but also enable in vitro intrinsic fluorescence imaging.
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Affiliation(s)
- Bong Han Lee
- Department of Physics and Astronomy, Texas Christian University, TCU Box 298840, Fort Worth, Texas 76129, United States of America
| | - Md Tanvir Hasan
- Department of Physics and Astronomy, Texas Christian University, TCU Box 298840, Fort Worth, Texas 76129, United States of America
- Biosystems and Biomaterials Division, National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, MD 20899, United States of America
| | - Denise Lichthardt
- Department of Physics and Astronomy, Texas Christian University, TCU Box 298840, Fort Worth, Texas 76129, United States of America
- Friedrich-Alexander University Erlangen-Nürnberg, Schlossplatz 4, 91054 Erlangen, Germany
| | - Roberto Gonzalez-Rodriguez
- Department of Physics and Astronomy, Texas Christian University, TCU Box 298840, Fort Worth, Texas 76129, United States of America
- Department of Physics, University of North Texas, 210 Avenue A, Denton, TX 76201, United States of America
| | - Anton V Naumov
- Department of Physics and Astronomy, Texas Christian University, TCU Box 298840, Fort Worth, Texas 76129, United States of America
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7
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Mondal S, Agam Y, Amdursky N. Enhanced Proton Conductivity across Protein Biopolymers Mediated by Doped Carbon Nanoparticles. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2020; 16:e2005526. [PMID: 33108059 DOI: 10.1002/smll.202005526] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2020] [Indexed: 06/11/2023]
Abstract
Carbon nanoparticles, known as carbon-dots (C-Dots), are famous for their optoelectronic properties. Here it is shown that C-Dots can also mediate protons, where protein biopolymers are used as the protonic transport matrix. Energy transfer measurements indicate that different doped C-Dots bind to the protein biopolymer in different efficiencies. Electrical impedance measurements reveal enhanced conductance across the protein biopolymer upon C-Dots integration, dependent on the doping type. The enhanced conductivity is attributed to protonic conduction due to the large observed kinetic isotope effect, resulting in one of the highest measured proton conductivity across protein biopolymers. Transistor measurements show that the various doped C-Dots-protein biopolymer exhibit different increase in charge carrier density and in carrier mobility, suggesting different modes of proton transport. The ability of C-Dots to support protonic conduction opens a field of carbon-based protonic nanoparticles and due to the formation simplicity of C-Dots they can be integrated in a variety of protonic devices.
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Affiliation(s)
- Somen Mondal
- Schulich Faculty of Chemistry, Technion - Israel Institute of Technology, Haifa, 3200003, Israel
| | - Yuval Agam
- Schulich Faculty of Chemistry, Technion - Israel Institute of Technology, Haifa, 3200003, Israel
| | - Nadav Amdursky
- Schulich Faculty of Chemistry, Technion - Israel Institute of Technology, Haifa, 3200003, Israel
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8
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Kuo WS, Shen XC, Chang CY, Kao HF, Lin SH, Wang JY, Wu PC. Multiplexed Graphene Quantum Dots with Excitation-Wavelength-Independent Photoluminescence, as Two-Photon Probes, and in Ultraviolet-Near Infrared Bioimaging. ACS NANO 2020; 14:11502-11509. [PMID: 32790323 DOI: 10.1021/acsnano.0c03915] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
In this study, sorted nitrogen-doped graphene quantum dots were prepared and subsequently conjugated with polymers. The synthesized materials exhibited excitation-wavelength-independent photoluminescence emissions ranging from ultraviolet to near-infrared and were 0.9-8.4 nm in size. The materials also exhibited high-photoluminescence quantum yields and excellent two-photon properties. Therefore, in two-photon bioimaging the materials with different emission spectra can be effective two-photon contrast agents. Specific antibodies were used to label organelles in cancer cells and identify nuclear antigens, thereby enabling the simultaneous detection of four targets in cells at a single two-photon excitation wavelength. The sorted nitrogen-doped graphene quantum dot materials were determined to be considerably more advantageous than organic dyes in identifying multiplexed targets, and they can be effective probes in cellular imaging.
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Affiliation(s)
- Wen-Shuo Kuo
- School of Chemistry and Materials Science, Nanjing University of Information Science and Technology, Nanjing 210044, Jiangsu China
- Allergy and Clinical Immunology Research Center, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, Tainan 701, Taiwan, Republic of China
| | - Xing-Can Shen
- State Key Laboratory for the Chemistry and Molecular Engineering of Medicinal Resources (Ministry of Education), School of Chemistry and Pharmaceutical Sciences, Guangxi Normal University, Guilin 541004, China
| | - Chia-Yuan Chang
- Department of Mechanical Engineering, National Cheng Kung University, Tainan 701, Taiwan, Republic of China
| | - Hui-Fang Kao
- Department of Nursing, National Tainan Junior College of Nursing, Tainan 700, Taiwan, Republic of China
| | - Sheng-Han Lin
- Department of Anesthesiology, E-Da Hospital, Kaohsiung 824, Taiwan, Republic of China
| | - Jiu-Yao Wang
- Allergy and Clinical Immunology Research Center, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, Tainan 701, Taiwan, Republic of China
- Department of Pediatrics, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, Tainan 701, Taiwan, Republic of China
| | - Ping-Ching Wu
- Department of Biomedical Engineering, National Cheng Kung University, Tainan 701, Taiwan, Republic of China
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9
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Understanding the Detection Mechanisms and Ability of Molecular Hydrogen on Three-Dimensional Bicontinuous Nanoporous Reduced Graphene Oxide. MATERIALS 2020; 13:ma13102259. [PMID: 32422953 PMCID: PMC7288210 DOI: 10.3390/ma13102259] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Revised: 05/07/2020] [Accepted: 05/12/2020] [Indexed: 12/02/2022]
Abstract
Environmental safety has become increasingly important with respect to hydrogen use in society. Monitoring techniques for explosive gaseous hydrogen are essential to ensure safety in sustainable hydrogen utilization. Here, we reveal molecular hydrogen detection mechanisms with monolithic three-dimensional nanoporous reduced graphene oxide under gaseous hydrogen flow and at room temperature. Nanoporous reduced graphene oxide significantly increased molecular hydrogen physisorption without the need to employ catalytic metals or heating. This can be explained by the significantly increased surface area in comparison to two-dimensional graphene sheets and conventional reduced graphene oxide flakes. Using this large surface area, molecular hydrogen adsorption behaviors were accurately observed. In particular, we found that the electrical resistance firstly decreased and then gradually increased with higher gaseous hydrogen concentrations. The resistance decrease was due to charge transfer from the molecular hydrogen to the reduced graphene oxide at adsorbed molecular hydrogen concentrations lower than 2.8 ppm; conversely, the resistance increase was a result of Coulomb scattering effects at adsorbed molecular hydrogen concentrations exceeding 5.0 ppm, as supported by density functional theory. These findings not only provide the detailed adsorption mechanisms of molecular hydrogen, but also advance the development of catalyst-free non-heated physisorption-type molecular detection devices.
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10
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Huo Z, Chen G, Geng Y, Cong L, Pan L, Xu W, Xu S. A two-photon fluorescence, carbonized polymer dot (CPD)-based, wide range pH nanosensor: a view from the surface state. NANOSCALE 2020; 12:9094-9103. [PMID: 32286603 DOI: 10.1039/d0nr01543a] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
A green-emitting, low-toxicity carbonized polymer dot (CPD) with a high fluorescence quantum yield was synthesised by a simple hydrothermal method, and has been applied as a three-mode pH indicator and the pH readouts involve the intensity ratio of the absorption bands, the single-photon fluorescence, and the two-photon fluorescence (TPF) signals. The pH sensing mechanism of this CPD is dependent on the hydrogen ion regulation on its surface states, which is evidenced for the first time by transient spectroscopy. The rich surface states of this CPD allow a wider pH-responsive range relative to other carbon nanodot-based pH nanosensors. Its ultra-small size, low cell toxicity, high brightness and stability are conducive to intracellular pH sensing under the TPF imaging. Our study is helpful for the development of novel carbon-based sensing materials based on the design of the surface states. It also provides a new candidate for up-conversion photoluminescence-responsive imaging agents and it has potential applications in the diagnosis and dynamic monitoring of cells relying on the pH evolution.
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Affiliation(s)
- Zepeng Huo
- State Key Laboratory of Supramolecular Structure and Materials, Institute of Theoretical Chemistry, College of Chemistry, Jilin University, Changchun 130012, P. R. China.
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11
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Liang M, Zhang Z, Long R, Wang Y, Yu Y, Pei Y. Design of a Z-scheme g-C 3N 4/CQDs/CdIn 2S 4 composite for efficient visible-light-driven photocatalytic degradation of ibuprofen. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2020; 259:113770. [PMID: 31918126 DOI: 10.1016/j.envpol.2019.113770] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/11/2019] [Revised: 11/12/2019] [Accepted: 12/07/2019] [Indexed: 06/10/2023]
Abstract
A novel Z-scheme photocatalyst consisting of acidified graphitic carbon nitrogen (ag-C3N4)/carbon quantum dots/CdIn2S4 (CN/CQDs/CIS) was successfully synthesized via a one-step hydrothermal method. The optimized CN-2/CQDs-3/CIS exhibited significantly improved photocatalytic performance in the degradation of ibuprofen under visible-light irradiation. Based on a series of characterizations, the ag-C3N4 and CQDs were distributed uniformly on the surface of the cubic spinel structure of CIS, with intimate contact among the materials. This intimate heterogeneous interface facilitated the migration of photogenerated carriers, further leading to enhanced photocatalytic performance. These results also indicated that the CQDs not only connect ag-C3N4 with CIS through covalent bonds but also enhance the visible-light adsorption. According to the analysis of the UV-vis diffuse reflectance spectra (DRS) and Mott-Schottky curves, the mechanism of the Z-scheme heterojunction is proposed. The CQDs serve as electron mediators and transfer the electrons in the conduction band (CB) of ag-C3N4 to recombine with the holes in the valence band (VB) of CIS in the Z-scheme, leading to the enhanced separation efficiency of the photogenerated electrons in the CB of ag-C3N4 and the holes in the VB of CIS. The pollutant IBU was degraded by h+, ·O2- and ·OH, as determined by electron paramagnetic resonance (EPR) analysis.
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Affiliation(s)
- Mingxing Liang
- The Key Laboratory of Water and Sediment Sciences, Ministry of Education, School of Environment, Beijing Normal University, Beijing 100875, PR China
| | - Zhaosheng Zhang
- The Key Laboratory of Theoretical & Computational Photochemistry of Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, PR China
| | - Run Long
- The Key Laboratory of Theoretical & Computational Photochemistry of Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, PR China
| | - Ying Wang
- The Key Laboratory of Water and Sediment Sciences, Ministry of Education, School of Environment, Beijing Normal University, Beijing 100875, PR China.
| | - Yajing Yu
- School of Chemical and Environmental Engineering, China University of Mining & Technology (Beijing), Beijing 100083, PR China
| | - Yuansheng Pei
- The Key Laboratory of Water and Sediment Sciences, Ministry of Education, School of Environment, Beijing Normal University, Beijing 100875, PR China
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12
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Wang Y, Wang L, Wang HY, Gao BR, Sun HB. Transient Depolarization Spectroscopic Study on Electronic Structure and Fluorescence Origin of Graphene Oxide. J Phys Chem Lett 2020; 11:1483-1489. [PMID: 32017570 DOI: 10.1021/acs.jpclett.9b03613] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
It is well-established that the electronic states of graphene oxide (GO) consist of sp2 clusters with different sizes and the surrounding sp3 matrix according to recent reports. However, addressing the excitation energy migration/redistribution among those electronic states in GO-based complex systems from spectroscopic experiments is still a challenge. Here, we combine the time-resolved absorption and fluorescence depolarization experiments to reveal the excitation energy migration processes in electronic states in GO. We demonstrate that, in sp3 domains of GO, there are charge-transfer states between sp3-hybridized carbon atoms and the oxygen-containing functional groups, and the energy redistribution and charge migration in sp3 matrix occur on the time scale from subpicoseconds to tens of picoseconds. In contrast, the electronic states of sp2 clusters in GO are rather localized and dominantly contribute to the excitation-wavelength-dependent red fluorescence of GO.
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Affiliation(s)
- Yan Wang
- State Key Laboratory of Integrated Optoelectronics, College of Electronic Science and Engineering , Jilin University , 2699 Qianjin Street , Changchun 130012 , China
| | - Lei Wang
- State Key Laboratory of Integrated Optoelectronics, College of Electronic Science and Engineering , Jilin University , 2699 Qianjin Street , Changchun 130012 , China
| | - Hai-Yu Wang
- State Key Laboratory of Integrated Optoelectronics, College of Electronic Science and Engineering , Jilin University , 2699 Qianjin Street , Changchun 130012 , China
| | - Bing-Rong Gao
- State Key Laboratory of Integrated Optoelectronics, College of Electronic Science and Engineering , Jilin University , 2699 Qianjin Street , Changchun 130012 , China
| | - Hong-Bo Sun
- State Key Laboratory of Integrated Optoelectronics, College of Electronic Science and Engineering , Jilin University , 2699 Qianjin Street , Changchun 130012 , China
- State Key Laboratory of Precision Measurement Technology and Instruments, Department of Precision Instrument , Tsinghua University , Haidian, Beijing 100084 , China
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Kohl FR, Grieco C, Kohler B. Ultrafast spectral hole burning reveals the distinct chromophores in eumelanin and their common photoresponse. Chem Sci 2019; 11:1248-1259. [PMID: 34123249 PMCID: PMC8148383 DOI: 10.1039/c9sc04527a] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Eumelanin, the brown-black pigment found in organisms from bacteria to humans, dissipates solar energy and prevents photochemical damage. While the structure of eumelanin is unclear, it is thought to consist of an extremely heterogeneous collection of chromophores that absorb from the UV to the infrared, additively producing its remarkably broad absorption spectrum. However, the chromophores responsible for absorption by eumelanin and their excited state decay pathways remain highly uncertain. Using femtosecond broadband transient absorption spectroscopy, we address the excited state behavior of chromophore subsets that make up a synthetic eumelanin, DOPA melanin, and probe the heterogeneity of its chromophores. Tuning the excitation light over more than an octave from the UV to the visible and probing with the broadest spectral window used to study any form of melanin to date enable the detection of spectral holes with a linewidth of 0.6 eV that track the excitation wavelength. Transient spectral hole burning is a manifestation of extreme chemical heterogeneity, yet exciting these diverse chromophores unexpectedly produces a common photoinduced absorption spectrum and similar kinetics. This common photoresponse is assigned to the ultrafast formation of immobile charge transfer excitons that decay locally and that are formed among graphene-like chromophores in less than 200 fs. Raman spectroscopy reveals that chromophore heterogeneity in DOPA melanin arises from different sized domains of sp2-hybridized carbon and nitrogen atoms. Furthermore, we identify for the first time striking parallels between the excited state dynamics of eumelanin and disordered carbon nanomaterials, suggesting that they share common structural attributes. Seeing the colors in black: ultrafast transient hole burning spectroscopy reveals the absorption properties of discrete chromophores and their interactions in the skin pigment eumelanin.![]()
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Affiliation(s)
- Forrest R Kohl
- Department of Chemistry and Biochemistry, The Ohio State University 100 West 18th Avenue Columbus Ohio 43210 USA +1-614-688-2635
| | - Christopher Grieco
- Department of Chemistry and Biochemistry, The Ohio State University 100 West 18th Avenue Columbus Ohio 43210 USA +1-614-688-2635
| | - Bern Kohler
- Department of Chemistry and Biochemistry, The Ohio State University 100 West 18th Avenue Columbus Ohio 43210 USA +1-614-688-2635
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14
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Abstract
Unexpectedly bright photoluminescence emission can be observed in materials incorporating inorganic carbon when their size is reduced from macro–micro to nano. At present, there is no consensus in its understanding, and many suggested explanations are not consistent with the broad range of experimental data. In this Review, I discuss the possible role of collective excitations (excitons) generated by resonance electronic interactions among the chromophore elements within these nanoparticles. The Förster-type resonance energy transfer (FRET) mechanism of energy migration within nanoparticles operates when the composing fluorophores are the localized electronic systems interacting at a distance. Meanwhile, the resonance interactions among closely located fluorophores may lead to delocalization of the excited states over many molecules resulting in Frenkel excitons. The H-aggregate-type quantum coherence originating from strong coupling among the transition dipoles of adjacent chromophores in a co-facial stacking arrangement and exciton transport to emissive traps are the basis of the presented model. It can explain most of the hitherto known experimental observations and must stimulate the progress towards their versatile applications.
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15
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Hasan MT, Gonzalez-Rodriguez R, Ryan C, Coffer JL, Naumov AV. Variation of Optical Properties of Nitrogen-doped Graphene Quantum Dots with Short/Mid/Long-wave Ultraviolet for the Development of the UV Photodetector. ACS APPLIED MATERIALS & INTERFACES 2019; 11:39035-39045. [PMID: 31553149 DOI: 10.1021/acsami.9b10365] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Nitrogen-doped graphene quantum dots (NGQDs) synthesized from a single glucosamine precursor are utilized to develop a novel UV photodetector. Optical properties of NGQDs can be altered with short- (254 nm), mid- (302 nm), and long-wave (365 nm) ultraviolet (UV) exposure leading to the reduction of absorption from deep to mid UV (200-320 nm) and enhancement above 320 nm. Significant quenching of blue and near-IR fluorescence accompanied by the dramatic increase of green/yellow emission of UV-treated NGQDs can be used as a potential UV-sensing mechanism. These emission changes are attributed to the reduction of functional groups detected by Fourier transformed infrared spectroscopy and free-radical-driven polymerization of the NGQDs increasing their average size from 4.70 to 11.20 nm at 60 min treatment. Due to strong UV absorption and sensitivity to UV irradiation, NGQDs developed in this work are utilized to fabricate UV photodetectors. Tested under long-/mid-/short-wave UV, these devices show high photoresponsivity (up to 0.59 A/W) and excellent photodetectivity (up to 1.03 × 1011 Jones) with highly characteristic wavelength-dependent reproducible response. This study suggests that the optical/structural properties of NGQDs can be controllably altered via different wavelength UV treatment leading us to fabricate NGQD-based novel UV photodetectors providing high responsivity and detectivity.
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Affiliation(s)
- Md Tanvir Hasan
- Department of Physics and Astronomy , Texas Christian University , TCU Box 298840, Fort Worth , Texas 76129 , United States
| | - Roberto Gonzalez-Rodriguez
- Department of Chemistry and Biochemistry , Texas Christian University , TCU Box 298860, Fort Worth , Texas 76129 , United States
| | - Conor Ryan
- Department of Physics and Astronomy , Texas Christian University , TCU Box 298840, Fort Worth , Texas 76129 , United States
| | - Jeffery L Coffer
- Department of Chemistry and Biochemistry , Texas Christian University , TCU Box 298860, Fort Worth , Texas 76129 , United States
| | - Anton V Naumov
- Department of Physics and Astronomy , Texas Christian University , TCU Box 298840, Fort Worth , Texas 76129 , United States
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16
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Mondal S, Yucknovsky A, Akulov K, Ghorai N, Schwartz T, Ghosh HN, Amdursky N. Efficient Photosensitizing Capabilities and Ultrafast Carrier Dynamics of Doped Carbon Dots. J Am Chem Soc 2019; 141:15413-15422. [PMID: 31453686 DOI: 10.1021/jacs.9b08071] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Carbon dots (C-Dots) are promising new materials for the development of biocompatible photosensitizers for solar-driven catalysis and hydrogen production in aqueous solution. Compared to common semiconducting quantum dots, C-Dots have good physicochemical, as well as photochemical stability, optical brightness, stability and nontoxicity, while their carbon based source results in tunable surface chemistry, chemical versatility, low cost, and biocompatibility. Herein we show that doping the C-Dots with phosphate or boron significantly influences their excited-state dynamics, which is observed by the formation of a unique long-lived photoproduct as a function of the different dopants. To probe the photosensitizing capabilities of the C-Dots, we followed the photoreduction of methyl viologen (MV2+), which acts as a molecular redox mediator (electron acceptor) to the C-Dots (the photosensitizer, i.e., electron donor) in aqueous solution, using steady-state and time-resolved fluorescence and absorption spectroscopic techniques as well as electrochemical measurements. We show that ultrafast electron transfer to MV2+ and slow charge recombination results in a high quantum yield of MV2+ photoreduction, while the doping drastically influences this quantum yield of MV2+ radical. Our findings contribute to the photophysical understanding of this intriguing and relatively new carbon-based nanoparticle and can improve the design and development of efficient photosensitizers over commonly used heterogeneous catalysts in photocatalytic systems by increasing the efficiency of radical generation.
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Affiliation(s)
- Somen Mondal
- Schulich Faculty of Chemistry , Technion-Israel Institute of Technology , Haifa 3200003 , Israel
| | - Anna Yucknovsky
- Schulich Faculty of Chemistry , Technion-Israel Institute of Technology , Haifa 3200003 , Israel
| | - Katherine Akulov
- School of Chemistry , Tel Aviv University , Tel Aviv 6997801 , Israel
| | - Nandan Ghorai
- Institute of Nano Science and Technology , Mohali , Punjab 160064 , India
| | - Tal Schwartz
- School of Chemistry , Tel Aviv University , Tel Aviv 6997801 , Israel
| | - Hirendra N Ghosh
- Institute of Nano Science and Technology , Mohali , Punjab 160064 , India
| | - Nadav Amdursky
- Schulich Faculty of Chemistry , Technion-Israel Institute of Technology , Haifa 3200003 , Israel
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17
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He X, Zhao L, Zhou Z, Zhang S, Pan H, Chen J, Xu J. Near unity charge separation efficiency leads to pure ultraviolet emission in few layer graphene nanosheets. NANOTECHNOLOGY 2019; 30:295201. [PMID: 30812023 DOI: 10.1088/1361-6528/ab0afe] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Two-dimensional materials with van der Waals structure attract intense interest due to their high performance in ultrathin optoelectronic devices. In particular, the high efficiency charge separation between the two-dimensional materials can significantly improve the photo-response of a given device. Here we report the discovery of pure ultraviolet (UV) emission from few layer graphene nanosheets (GNS). Near unity charge separation efficiency is key to pure UV emission. The dynamics of an excited electron were analyzed using femtosecond transient absorption techniques. Electron transfer is observed from surface defect states induced by oxygen-containing functional groups to intrinsic sp2 domain states in few layer GNS. Moreover, a solar blind response device based on few layer GNS with a high on-off ratio was successfully fabricated.
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Affiliation(s)
- Xiaoxiao He
- State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200062, People's Republic of China
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18
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Liu H, Jiang Y, Fan P, Feng Y, Lan J, Xu G, Zhu X, Zhang X, Hu X, Yang T, Yang B, Zhang Q, Li D, Wang X, Pan A. Polar-Induced Selective Epitaxial Growth of Multijunction Nanoribbons for High-Performance Optoelectronics. ACS APPLIED MATERIALS & INTERFACES 2019; 11:15813-15820. [PMID: 30964265 DOI: 10.1021/acsami.9b04470] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Semiconductor heterostructures are basic building blocks for modern electronics and optoelectronics. However, it still remains a great challenge to combine different semiconductor materials in single nanostructures with tailored geometry and chemical composition. Here, a polar-induced selective epitaxial growth method is reported to alternately grow CdS and CdS xSe1- x heterostructure nanoribbons (NRs) side by side in the lateral direction, with the heterointerface (junction) number to be well controlled. Transmission electron microscopy (TEM) and spatial-resolved μ-PL spectra are employed to characterize the heterostructure NRs, which indicate that the achieved NRs are high-quality heterostructures with sharp interfaces. Kelvin probe force microscopy (KPFM) and femtosecond pump-probe characterizations further confirm the efficient charge-transfer process across the interfaces in the multijunction NRs. Photodetectors based on the achieved NRs are realized and systematically investigated, demonstrating junction number-dependent optoelectronic response behaviors. NRs with more junctions exhibit more superior device performances, reflecting the important roles of the high-quality interface regions. Based on this multijunction NRs device, high on-off ratio (107) and remarkable responsivity (1.5 × 105 A/W) are demonstrated, both of which represent the best results compared to the reported CdS, CdSe, and their heterostructures. These novel multijunction NRs may find broad applications in future integrated photonics and optoelectronics devices and systems.
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Affiliation(s)
| | | | | | | | - Jianyue Lan
- Suzhou Institute of Nano-tech and Nano-Bionics, Chinese Academy of Sciences , Suzhou 215123 , People's Republic of China
| | - Gengzhao Xu
- Suzhou Institute of Nano-tech and Nano-Bionics, Chinese Academy of Sciences , Suzhou 215123 , People's Republic of China
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19
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He X, Zhang S, Pan H, Chen J, Xu J. Horizontally Aggregation of Monolayer Reduced Graphene Oxide Under Deep UV Irradiation in Solution. NANOSCALE RESEARCH LETTERS 2019; 14:117. [PMID: 30941577 PMCID: PMC6445836 DOI: 10.1186/s11671-019-2940-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/20/2018] [Accepted: 03/14/2019] [Indexed: 06/09/2023]
Abstract
Graphene has been widely used in novel optoelectronic devices in decades. Nowadays, fabrication of large size monolayer graphene with spectral selectivity is highly demanded. Here, we report a simple method for synthesizing large size monolayer graphene with chemical functionalized groups in solution. The few layer nano-graphene can be exfoliated into monolayer nano-graphene under short time UV irradiation in protic solution. The exfoliated monolayer nano-graphene could experience deoxygenation during long time UV exposure. At the same time, the edge of nano-graphene could be activated under deep UV exposure and small size nano-graphene sheets further aggregate horizontally in solution. The size of aggregated rGO increase from 40 nm to a maximum of 1 μm. This approach could be one promising cheap method for synthesizing large size monolayer reduced graphene oxide in the future.
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Affiliation(s)
- Xiaoxiao He
- State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai, 200062, China
| | - Sanjun Zhang
- State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai, 200062, China
| | - Haifeng Pan
- State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai, 200062, China
| | - Jinquan Chen
- State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai, 200062, China.
- Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan, 030006, Shanxi, China.
| | - Jianhua Xu
- State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai, 200062, China.
- Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan, 030006, Shanxi, China.
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20
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Teng CY, Nguyen BS, Yeh TF, Lee YL, Chen SJ, Teng H. Roles of nitrogen functionalities in enhancing the excitation-independent green-color photoluminescence of graphene oxide dots. NANOSCALE 2017; 9:8256-8265. [PMID: 28585974 DOI: 10.1039/c7nr01037k] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Fluorescent graphene oxide dots (GODs) are environmentally friendly and biocompatible materials for photoluminescence (PL) applications. In this study, we employed annealing and hydrothermal ammonia treatments at 500 and 140 °C, respectively, to introduce nitrogen functionalities into GODs for enhancing their green-color PL emissions. The hydrothermal treatment preferentially produces pyridinic and amino groups, whereas the annealing treatment produces pyrrolic and amide groups. The hydrothermally treated GODs (A-GODs) present a high conjugation of the nonbonding electrons of nitrogen in pyridinic and amino groups with the aromatic π orbital. This conjugation introduces a nitrogen nonbonding (nN 2p) state 0.3 eV above the oxygen nonbonding state (nO 2p state; the valence band maximum of the GODs). The GODs exhibit excitation-independent green-PL emissions at 530 nm with a maximum quantum yield (QY) of 12% at 470 nm excitation, whereas the A-GODs exhibit a maximum QY of 63%. The transformation of the solvent relaxation-governed π* → nO 2p transition in the GODs to the direct π* → nN 2p transition in the A-GODs possibly accounts for the substantial QY enhancement in the PL emissions. This study elucidates the role of nitrogen functionalities in the PL emissions of graphitic materials and proposes a strategy for designing the electronic structure to promote the PL performance.
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Affiliation(s)
- Chiao-Yi Teng
- Department of Chemical Engineering and Research Center for Energy Technology and Strategy, National Cheng Kung University, Tainan 70101, Taiwan.
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21
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Misra SK, Srivastava I, Tripathi I, Daza E, Ostadhossein F, Pan D. Macromolecularly “Caged” Carbon Nanoparticles for Intracellular Trafficking via Switchable Photoluminescence. J Am Chem Soc 2017; 139:1746-1749. [DOI: 10.1021/jacs.6b11595] [Citation(s) in RCA: 53] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
- Santosh K. Misra
- Departments of Bioengineering,
Beckman Institute, Materials Science and Engineering, Institute for
Sustainability in Energy and Environment, University of Illinois at Urbana−Champaign, Urbana, Illinois 61801, United States
- Mills Breast Cancer Institute, and Carle Foundation Hospital, Urbana, Illinois 61801, United States
| | - Indrajit Srivastava
- Departments of Bioengineering,
Beckman Institute, Materials Science and Engineering, Institute for
Sustainability in Energy and Environment, University of Illinois at Urbana−Champaign, Urbana, Illinois 61801, United States
- Mills Breast Cancer Institute, and Carle Foundation Hospital, Urbana, Illinois 61801, United States
| | - Indu Tripathi
- Departments of Bioengineering,
Beckman Institute, Materials Science and Engineering, Institute for
Sustainability in Energy and Environment, University of Illinois at Urbana−Champaign, Urbana, Illinois 61801, United States
- Mills Breast Cancer Institute, and Carle Foundation Hospital, Urbana, Illinois 61801, United States
| | - Enrique Daza
- Departments of Bioengineering,
Beckman Institute, Materials Science and Engineering, Institute for
Sustainability in Energy and Environment, University of Illinois at Urbana−Champaign, Urbana, Illinois 61801, United States
- Mills Breast Cancer Institute, and Carle Foundation Hospital, Urbana, Illinois 61801, United States
| | - Fatemeh Ostadhossein
- Departments of Bioengineering,
Beckman Institute, Materials Science and Engineering, Institute for
Sustainability in Energy and Environment, University of Illinois at Urbana−Champaign, Urbana, Illinois 61801, United States
- Mills Breast Cancer Institute, and Carle Foundation Hospital, Urbana, Illinois 61801, United States
| | - Dipanjan Pan
- Departments of Bioengineering,
Beckman Institute, Materials Science and Engineering, Institute for
Sustainability in Energy and Environment, University of Illinois at Urbana−Champaign, Urbana, Illinois 61801, United States
- Mills Breast Cancer Institute, and Carle Foundation Hospital, Urbana, Illinois 61801, United States
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22
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Slow cooling and efficient extraction of C-exciton hot carriers in MoS 2 monolayer. Nat Commun 2017; 8:13906. [PMID: 28054546 PMCID: PMC5227064 DOI: 10.1038/ncomms13906] [Citation(s) in RCA: 60] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2016] [Accepted: 11/09/2016] [Indexed: 12/22/2022] Open
Abstract
In emerging optoelectronic applications, such as water photolysis, exciton fission and novel photovoltaics involving low-dimensional nanomaterials, hot-carrier relaxation and extraction mechanisms play an indispensable and intriguing role in their photo-electron conversion processes. Two-dimensional transition metal dichalcogenides have attracted much attention in above fields recently; however, insight into the relaxation mechanism of hot electron-hole pairs in the band nesting region denoted as C-excitons, remains elusive. Using MoS2 monolayers as a model two-dimensional transition metal dichalcogenide system, here we report a slower hot-carrier cooling for C-excitons, in comparison with band-edge excitons. We deduce that this effect arises from the favourable band alignment and transient excited-state Coulomb environment, rather than solely on quantum confinement in two-dimension systems. We identify the screening-sensitive bandgap renormalization for MoS2 monolayer/graphene heterostructures, and confirm the initial hot-carrier extraction for the C-exciton state with an unprecedented efficiency of 80%, accompanied by a twofold reduction in the exciton binding energy. Light-matter interaction in atomically thin transition metal dichalcogenides is dominated by excitonic effects and hot-carrier relaxation/extraction mechanisms. Here, the authors report that the C exciton in two-dimensional MoS2 exhibits a slower hot-carrier cooling than band-edge excitons.
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23
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Chen NK, Han D, Li XB, Liu F, Bang J, Wang XP, Chen QD, Wang HY, Zhang S, Sun HB. Giant lattice expansion by quantum stress and universal atomic forces in semiconductors under instant ultrafast laser excitation. Phys Chem Chem Phys 2017; 19:24735-24741. [DOI: 10.1039/c7cp03103c] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Electronic excitation induced stress and force may provide a new route to manipulate the structure of materials using ultrafast lasers.
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24
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Elvati P, Baumeister E, Violi A. Graphene quantum dots: effect of size, composition and curvature on their assembly. RSC Adv 2017. [DOI: 10.1039/c7ra01029j] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The enhanced configurational stability of graphene quantum dots in clusters.
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Affiliation(s)
- Paolo Elvati
- Mechanical Engineering
- University of Michigan
- Ann Arbor
- USA
| | | | - Angela Violi
- Mechanical Engineering
- University of Michigan
- Ann Arbor
- USA
- Chemical Engineering
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25
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Yu H, Shi R, Zhao Y, Waterhouse GIN, Wu LZ, Tung CH, Zhang T. Smart Utilization of Carbon Dots in Semiconductor Photocatalysis. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2016; 28:9454-9477. [PMID: 27623955 DOI: 10.1002/adma.201602581] [Citation(s) in RCA: 307] [Impact Index Per Article: 38.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/15/2016] [Revised: 06/24/2016] [Indexed: 05/17/2023]
Abstract
Efficient capture of solar energy will be critical to meeting the energy needs of the future. Semiconductor photocatalysis is expected to make an important contribution in this regard, delivering both energy carriers (especially H2 ) and valuable chemical feedstocks under direct sunlight. Over the past few years, carbon dots (CDs) have emerged as a promising new class of metal-free photocatalyst, displaying semiconductor-like photoelectric properties and showing excellent performance in a wide variety of photoelectrochemical and photocatalytic applications owing to their ease of synthesis, unique structure, adjustable composition, ease of surface functionalization, outstanding electron-transfer efficiency and tunable light-harvesting range (from deep UV to the near-infrared). Here, recent advances in the rational design of CDs-based photocatalysts are highlighted and their applications in photocatalytic environmental remediation, water splitting into hydrogen, CO2 reduction, and organic synthesis are discussed.
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Affiliation(s)
- Huijun Yu
- Key Laboratory of Photochemical Conversion and Optoelectronic Materials, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, 100190, P. R. China
| | - Run Shi
- Key Laboratory of Photochemical Conversion and Optoelectronic Materials, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, 100190, P. R. China
- University of Chinese Academy of Sciences, Beijing, 100049, P. R. China
| | - Yufei Zhao
- Key Laboratory of Photochemical Conversion and Optoelectronic Materials, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, 100190, P. R. China
| | | | - Li-Zhu Wu
- Key Laboratory of Photochemical Conversion and Optoelectronic Materials, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, 100190, P. R. China
| | - Chen-Ho Tung
- Key Laboratory of Photochemical Conversion and Optoelectronic Materials, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, 100190, P. R. China
| | - Tierui Zhang
- Key Laboratory of Photochemical Conversion and Optoelectronic Materials, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, 100190, P. R. China
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26
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Yeh TF, Huang WL, Chung CJ, Chiang IT, Chen LC, Chang HY, Su WC, Cheng C, Chen SJ, Teng H. Elucidating Quantum Confinement in Graphene Oxide Dots Based On Excitation-Wavelength-Independent Photoluminescence. J Phys Chem Lett 2016; 7:2087-2092. [PMID: 27192445 DOI: 10.1021/acs.jpclett.6b00752] [Citation(s) in RCA: 62] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Investigating quantum confinement in graphene under ambient conditions remains a challenge. In this study, we present graphene oxide quantum dots (GOQDs) that show excitation-wavelength-independent photoluminescence. The luminescence color varies from orange-red to blue as the GOQD size is reduced from 8 to 1 nm. The photoluminescence of each GOQD specimen is associated with electron transitions from the antibonding π (π*) to oxygen nonbonding (n-state) orbitals. The observed quantum confinement is ascribed to a size change in the sp(2) domains, which leads to a change in the π*-π gap; the n-state levels remain unaffected by the size change. The electronic properties and mechanisms involved in quantum-confined photoluminescence can serve as the foundation for the application of oxygenated graphene in electronics, photonics, and biology.
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Affiliation(s)
- Te-Fu Yeh
- Department of Chemical Engineering and Research Center for Energy Technology and Strategy, National Cheng Kung University , Tainan 70101, Taiwan
| | - Wei-Lun Huang
- Department of Internal Medicine, College of Medicine and Hospital, National Cheng Kung University , Tainan 70101, Taiwan
| | - Chung-Jen Chung
- Center for Micro/Nano Science and Technology, National Cheng Kung University , Tainan 70101, Taiwan
| | - I-Ting Chiang
- Department of Internal Medicine, College of Medicine and Hospital, National Cheng Kung University , Tainan 70101, Taiwan
| | - Liang-Che Chen
- Department of Chemical Engineering and Research Center for Energy Technology and Strategy, National Cheng Kung University , Tainan 70101, Taiwan
| | - Hsin-Yu Chang
- Department of Engineering Science, National Cheng Kung University , Tainan 70101, Taiwan
| | - Wu-Chou Su
- Department of Internal Medicine, College of Medicine and Hospital, National Cheng Kung University , Tainan 70101, Taiwan
| | - Ching Cheng
- Department of Physics, National Cheng Kung University , Tainan 70101, Taiwan
| | - Shean-Jen Chen
- Center for Micro/Nano Science and Technology, National Cheng Kung University , Tainan 70101, Taiwan
- Department of Engineering Science, National Cheng Kung University , Tainan 70101, Taiwan
| | - Hsisheng Teng
- Department of Chemical Engineering and Research Center for Energy Technology and Strategy, National Cheng Kung University , Tainan 70101, Taiwan
- Center for Micro/Nano Science and Technology, National Cheng Kung University , Tainan 70101, Taiwan
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27
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Yu H, Li X, Zeng X, Lu Y. Preparation of carbon dots by non-focusing pulsed laser irradiation in toluene. Chem Commun (Camb) 2016; 52:819-22. [PMID: 26574881 DOI: 10.1039/c5cc08384b] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
A simple approach for preparing carbon dots (CDs) by non-focusing pulsed laser irradiation in toluene was presented. The as-prepared CDs were graphite dots, which were formed by ablating the intermediate graphene. The size of the as-prepared CDs could be easily controlled by the input of laser fluence. The mechanism of the photoluminescence was also discussed.
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Affiliation(s)
- Huiwu Yu
- Wuhan National Laboratory for Optoelectronics (WNLO), Huazhong University of Science and Technology (HUST), Wuhan, Hubei 430074, P. R. China.
| | - Xiangyou Li
- Wuhan National Laboratory for Optoelectronics (WNLO), Huazhong University of Science and Technology (HUST), Wuhan, Hubei 430074, P. R. China.
| | - Xiaoyan Zeng
- Wuhan National Laboratory for Optoelectronics (WNLO), Huazhong University of Science and Technology (HUST), Wuhan, Hubei 430074, P. R. China.
| | - Yongfeng Lu
- Wuhan National Laboratory for Optoelectronics (WNLO), Huazhong University of Science and Technology (HUST), Wuhan, Hubei 430074, P. R. China.
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28
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Sui L, Jin W, Li S, Liu D, Jiang Y, Chen A, Liu H, Shi Y, Ding D, Jin M. Ultrafast carrier dynamics of carbon nanodots in different pH environments. Phys Chem Chem Phys 2016; 18:3838-45. [DOI: 10.1039/c5cp07558k] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The carboxyl groups in C-dots greatly influence PL of C-dots as emissive surface states based on steady-state and transient absorption spectroscopy.
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Sun C, Zhang Y, Sun K, Reckmeier C, Zhang T, Zhang X, Zhao J, Wu C, Yu WW, Rogach AL. Combination of carbon dot and polymer dot phosphors for white light-emitting diodes. NANOSCALE 2015; 7:12045-50. [PMID: 26119869 DOI: 10.1039/c5nr03014e] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
We realized white light-emitting diodes with high color rendering index (85-96) and widely variable color temperatures (2805-7786 K) by combining three phosphors based on carbon dots and polymer dots, whose solid-state photoluminescence self-quenching was efficiently suppressed within a polyvinyl pyrrolidone matrix. All three phosphors exhibited dominant absorption in the UV spectral region, which ensured the weak reabsorption and no energy transfer crosstalk. The WLEDs showed excellent color stability against the increasing current because of the similar response of the tricolor phosphors to the UV light variation.
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Affiliation(s)
- Chun Sun
- State Key Laboratory on Integrated Optoelectronics, and College of Electronic Science and Engineering, Jilin University, Changchun 130012, China.
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Zhu S, Shao J, Song Y, Zhao X, Du J, Wang L, Wang H, Zhang K, Zhang J, Yang B. Investigating the surface state of graphene quantum dots. NANOSCALE 2015; 7:7927-33. [PMID: 25865229 DOI: 10.1039/c5nr01178g] [Citation(s) in RCA: 116] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
A universal route to GQDs is developed based on "solution phase-based scissor" methods. The PL centers of the GQDs are systematically studied and are proved to be the surface state. This is related to the hybridization structure of the edge groups and the connected partial graphene core. Through experiment and analysis, we have preliminarily proved that the efficient edge groups for green emission are mainly carboxyl, carbonyl and amide. This is indicated by the following three factors: firstly, the PL of GQDs is enhanced by UV exposure, during which partial -OH groups are converted into carboxyl groups; secondly, the PL properties of GQDs can be further improved by one-step solvothermal treatment, in which partial carboxyl groups are converted to amide groups and the surface state of the GQDs is enhanced; thirdly, reduced m-GQDs possess more -OH groups compared with reduced GQDs, resulting in more blue PL centers (the carboxyl, carbonyl and amide-based green centers are converted to -OH-based blue centers). The present work highlights a very important direction for the understanding of the PL mechanism of GQDs and other related carbon-based materials.
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Affiliation(s)
- Shoujun Zhu
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, 2699 Qianjin Street, Changchun 130012, China.
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31
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Fan T, Zeng W, Tang W, Yuan C, Tong S, Cai K, Liu Y, Huang W, Min Y, Epstein AJ. Controllable size-selective method to prepare graphene quantum dots from graphene oxide. NANOSCALE RESEARCH LETTERS 2015; 10:55. [PMID: 25852352 PMCID: PMC4385023 DOI: 10.1186/s11671-015-0783-9] [Citation(s) in RCA: 64] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2014] [Accepted: 01/24/2015] [Indexed: 05/27/2023]
Abstract
We demonstrated one-step method to fabricate two different sizes of graphene quantum dots (GQDs) through chemical cutting from graphene oxide (GO), which had many advantages in terms of simple process, low cost, and large scale in manufacturing with higher production yield comparing to the reported methods. Several analytical methods were employed to characterize the composition and morphology of the resultants. Bright blue luminescent GQDs were obtained with a produced yield as high as 34.8%. Moreover, how the different sizes affect fluorescence wavelength mechanism was investigated in details.
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Affiliation(s)
- Tianju Fan
- />Institute of Advanced Materials, Nanjing University of Posts and Telecommunications, 9 Wenyuan Road, Nanjing, Jiangsu 210046 China
| | - Wenjin Zeng
- />Institute of Advanced Materials, Nanjing University of Posts and Telecommunications, 9 Wenyuan Road, Nanjing, Jiangsu 210046 China
| | - Wei Tang
- />Institute of Advanced Materials, Nanjing University of Posts and Telecommunications, 9 Wenyuan Road, Nanjing, Jiangsu 210046 China
| | - Chunqiu Yuan
- />Institute of Advanced Materials, Nanjing University of Posts and Telecommunications, 9 Wenyuan Road, Nanjing, Jiangsu 210046 China
| | - Songzhao Tong
- />Institute of Advanced Materials, Nanjing University of Posts and Telecommunications, 9 Wenyuan Road, Nanjing, Jiangsu 210046 China
| | - Kaiyu Cai
- />Institute of Advanced Materials, Nanjing University of Posts and Telecommunications, 9 Wenyuan Road, Nanjing, Jiangsu 210046 China
| | - Yidong Liu
- />State Key Laboratory of Organic Electronics and Information Displays and Fountain Global Photoelectric Technology Co. Ltd, 2 Xinyue Road, Yancheng, Jiangsu 224000 China
| | - Wei Huang
- />Institute of Advanced Materials, Nanjing University of Posts and Telecommunications, 9 Wenyuan Road, Nanjing, Jiangsu 210046 China
- />State Key Laboratory of Organic Electronics and Information Displays and Fountain Global Photoelectric Technology Co. Ltd, 2 Xinyue Road, Yancheng, Jiangsu 224000 China
| | - Yong Min
- />Institute of Advanced Materials, Nanjing University of Posts and Telecommunications, 9 Wenyuan Road, Nanjing, Jiangsu 210046 China
- />Department of Physics and Chemistry & Biochemistry, The Ohio State University, Columbus, OH 43210 USA
| | - Arthur J Epstein
- />Department of Physics and Chemistry & Biochemistry, The Ohio State University, Columbus, OH 43210 USA
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Kan X, Su B, Jiang L. Precisely patterning graphene sheets through a liquid-bridge induced strategy. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2014; 10:2570-2577. [PMID: 24678030 DOI: 10.1002/smll.201303903] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2013] [Revised: 02/21/2014] [Indexed: 06/03/2023]
Affiliation(s)
- Xiaonan Kan
- Beijing National Laboratory for Molecular Sciences (BNLMS), Key Laboratory of Organic Solids and Laboratory of New Materials, Institute of Chemistry, Chinese Academy of Sciences (ICCAS), Beijing, 100190, China
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Wang L, Zhu SJ, Wang HY, Qu SN, Zhang YL, Zhang JH, Chen QD, Xu HL, Han W, Yang B, Sun HB. Common origin of green luminescence in carbon nanodots and graphene quantum dots. ACS NANO 2014; 8:2541-7. [PMID: 24517361 DOI: 10.1021/nn500368m] [Citation(s) in RCA: 403] [Impact Index Per Article: 40.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Carbon nanodots (C-dots) synthesized by electrochemical ablation and small molecule carbonization, as well as graphene quantum dots (GQDs) fabricated by solvothermally cutting graphene oxide, are three kinds of typical green fluorescence carbon nanomaterials. Insight into the photoluminescence origin in these fluorescent carbon nanomaterials is one of the important matters of current debates. Here, a common origin of green luminescence in these C-dots and GQDs is unraveled by ultrafast spectroscopy. According to the change of surface functional groups during surface chemical reduction experiments, which are also accompanied by obvious emission-type transform, these common green luminescence emission centers that emerge in these C-dots and GQDs synthesized by bottom-up and top-down methods are unambiguously assigned to special edge states consisting of several carbon atoms on the edge of carbon backbone and functional groups with C═O (carbonyl and carboxyl groups). Our findings further suggest that the competition among various emission centers (bright edge states) and traps dominates the optical properties of these fluorescent carbon nanomaterials.
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Affiliation(s)
- Lei Wang
- State Key Laboratory on Integrated Optoelectronics, College of Electronic Science and Engineering, ‡State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, and §College of Physics, Jilin University , 2699 Qianjin Street, Changchun 130012, China
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Zhu S, Wang L, Zhou N, Zhao X, Song Y, Maharjan S, Zhang J, Lu L, Wang H, Yang B. The crosslink enhanced emission (CEE) in non-conjugated polymer dots: from the photoluminescence mechanism to the cellular uptake mechanism and internalization. Chem Commun (Camb) 2014; 50:13845-8. [DOI: 10.1039/c4cc05806b] [Citation(s) in RCA: 196] [Impact Index Per Article: 19.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The crosslink enhanced emission (CEE) in a new type of non-conjugated polymer dots (PDs) is reported.
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Affiliation(s)
- Shoujun Zhu
- State Key Laboratory of Supramolecular Structure and Materials
- College of Chemistry
- Jilin University
- Changchun, P. R. China
| | - Lei Wang
- State Key Laboratory of Integrated Optoelectronics
- College of Electronic Science and Engineering
- Jilin University
- Changchun, P. R. China
| | - Nan Zhou
- Department of Hand Surgery
- the First Hospital of Jilin University
- Changchun, P. R. China
| | - Xiaohuan Zhao
- State Key Laboratory of Supramolecular Structure and Materials
- College of Chemistry
- Jilin University
- Changchun, P. R. China
| | - Yubin Song
- State Key Laboratory of Supramolecular Structure and Materials
- College of Chemistry
- Jilin University
- Changchun, P. R. China
| | - Suraj Maharjan
- Department of Hand Surgery
- the First Hospital of Jilin University
- Changchun, P. R. China
| | - Junhu Zhang
- State Key Laboratory of Supramolecular Structure and Materials
- College of Chemistry
- Jilin University
- Changchun, P. R. China
| | - Laijin Lu
- Department of Hand Surgery
- the First Hospital of Jilin University
- Changchun, P. R. China
| | - Haiyu Wang
- State Key Laboratory of Integrated Optoelectronics
- College of Electronic Science and Engineering
- Jilin University
- Changchun, P. R. China
| | - Bai Yang
- State Key Laboratory of Supramolecular Structure and Materials
- College of Chemistry
- Jilin University
- Changchun, P. R. China
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