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Austin R, Farah Y, Sayer T, Luther B, Montoya-Castillo A, Krummel A, Sambur J. Hot carrier extraction from 2D semiconductor photoelectrodes. Proc Natl Acad Sci U S A 2023; 120:e2220333120. [PMID: 37011201 PMCID: PMC10104502 DOI: 10.1073/pnas.2220333120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2022] [Accepted: 03/07/2023] [Indexed: 04/05/2023] Open
Abstract
Hot carrier-based energy conversion systems could double the efficiency of conventional solar energy technology or drive photochemical reactions that would not be possible using fully thermalized, "cool" carriers, but current strategies require expensive multijunction architectures. Using an unprecedented combination of photoelectrochemical and in situ transient absorption spectroscopy measurements, we demonstrate ultrafast (<50 fs) hot exciton and free carrier extraction under applied bias in a proof-of-concept photoelectrochemical solar cell made from earth-abundant and potentially inexpensive monolayer (ML) MoS2. Our approach facilitates ultrathin 7 Å charge transport distances over 1 cm2 areas by intimately coupling ML-MoS2 to an electron-selective solid contact and a hole-selective electrolyte contact. Our theoretical investigations of the spatial distribution of exciton states suggest greater electronic coupling between hot exciton states located on peripheral S atoms and neighboring contacts likely facilitates ultrafast charge transfer. Our work delineates future two-dimensional (2D) semiconductor design strategies for practical implementation in ultrathin photovoltaic and solar fuel applications.
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Affiliation(s)
- Rachelle Austin
- Department of Chemistry, Colorado State University, Fort Collins, CO80523
| | - Yusef R. Farah
- Department of Chemistry, Colorado State University, Fort Collins, CO80523
| | - Thomas Sayer
- Department of Chemistry, University of Colorado Boulder, Boulder, CO80309
| | - Bradley M. Luther
- Department of Chemistry, Colorado State University, Fort Collins, CO80523
| | | | - Amber T. Krummel
- Department of Chemistry, Colorado State University, Fort Collins, CO80523
| | - Justin B. Sambur
- Department of Chemistry, Colorado State University, Fort Collins, CO80523
- School of Advanced Materials Discovery, Colorado State University, Fort Collins, CO80523
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2
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Chen X, Wang X, Pang Y, Bao G, Jiang J, Yang P, Chen Y, Rao T, Liao W. Printed Electronics Based on 2D Material Inks: Preparation, Properties, and Applications toward Memristors. SMALL METHODS 2023; 7:e2201156. [PMID: 36610015 DOI: 10.1002/smtd.202201156] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/05/2022] [Revised: 12/07/2022] [Indexed: 06/17/2023]
Abstract
Printed electronics, which fabricate electrical components and circuits on various substrates by leveraging functional inks and advanced printing technologies, have recently attracted tremendous attention due to their capability of large-scale, high-speed, and cost-effective manufacturing and also their great potential in flexible and wearable devices. To further achieve multifunctional, practical, and commercial applications, various printing technologies toward smarter pattern-design, higher resolution, greater production flexibility, and novel ink formulations toward multi-functionalities and high quality have been insensitively investigated. 2D materials, possessing atomically thin thickness, unique properties and excellent solution-processable ability, hold great potential for high-quality inks. Besides, the great variety of 2D materials ranging from metals, semiconductors to insulators offers great freedom to formulate versatile inks to construct various printed electronics. Here, a detailed review of the progress on 2D material inks formulation and its printed applications has been provided, specifically with an emphasis on emerging printed memristors. Finally, the challenges facing the field and prospects of 2D material inks and printed electronics are discussed.
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Affiliation(s)
- Xiaopei Chen
- College of Electronics and Information Engineering, Shenzhen University, Shenzhen, 518060, China
| | - Xiongfeng Wang
- College of Electronics and Information Engineering, Shenzhen University, Shenzhen, 518060, China
| | - Yudong Pang
- College of Electronics and Information Engineering, Shenzhen University, Shenzhen, 518060, China
| | - Guocheng Bao
- College of Electronics and Information Engineering, Shenzhen University, Shenzhen, 518060, China
| | - Jie Jiang
- College of Electronics and Information Engineering, Shenzhen University, Shenzhen, 518060, China
| | - Peng Yang
- College of Electronics and Information Engineering, Shenzhen University, Shenzhen, 518060, China
- College of Integrated Circuits and Optoelectronic Chips, Shenzhen Technology University, Shenzhen, 518118, China
| | - Yuankang Chen
- College of Electronics and Information Engineering, Shenzhen University, Shenzhen, 518060, China
| | - Tingke Rao
- College of Electronics and Information Engineering, Shenzhen University, Shenzhen, 518060, China
| | - Wugang Liao
- College of Electronics and Information Engineering, Shenzhen University, Shenzhen, 518060, China
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Fabrication of near-invisible solar cell with monolayer WS 2. Sci Rep 2022; 12:11315. [PMID: 35787666 PMCID: PMC9253307 DOI: 10.1038/s41598-022-15352-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2022] [Accepted: 06/22/2022] [Indexed: 11/08/2022] Open
Abstract
Herein, we developed a near-invisible solar cell through a precise control of the contact barrier between an indium tin oxide (ITO) electrode and a monolayer tungsten disulfide (WS2), grown by chemical vapor deposition (CVD). The contact barrier between WS2 and ITO was controlled by coating various thin metals on top of ITO (Mx/ITO) and inserting a thin layer of WO3 between Mx/ITO and the monolayer WS2, which resulted in a drastic increase in the Schottky barrier height (up to 220 meV); this could increase the efficiency of the charge carrier separation in our Schottky-type solar cell. The power conversion efficiency (PCE) of the solar cell with the optimized electrode (WO3/Mx/ITO) was more than 1000 times that of a device using a normal ITO electrode. Large-scale fabrication of the solar cell was also investigated, which revealed that a simple size expansion with large WS2 crystals and parallel long electrodes could not improve the total power (PT) obtained from the complete device even with an increase in the device area; this can be explained by the percolation theory. This problem was addressed by reducing the aspect ratio (width/channel length) of the unit device structure to a value lower than a critical threshold. By repeating the experiments on this optimized unit device with an appropriate number of series and parallel connections, PT could be increased up to 420 pW from a 1-cm2 solar cell with a very high value (79%) of average visible transmission (AVT).
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Mao H, Yang H, Liu J, Zhang S, Liu D, Wu Q, Sun W, Song XM, Ma T. Improved nitrogen reduction electroactivity by unique MoS2-SnS2 heterogeneous nanoplates supported on poly(zwitterionic liquids) functionalized polypyrrole/graphene oxide. CHINESE JOURNAL OF CATALYSIS 2022. [DOI: 10.1016/s1872-2067(21)63944-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Lee H, Han H, Park C, Oh JW, Kim HH, Kim S, Koo M, Choi WK, Park C. Halide Perovskite Nanocrystal-Enabled Stabilization of Transition Metal Dichalcogenide Nanosheets. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2022; 18:e2106035. [PMID: 34923744 DOI: 10.1002/smll.202106035] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Revised: 11/25/2021] [Indexed: 06/14/2023]
Abstract
Transition metal dichalcogenide (TMD) nanosheets exfoliated in the liquid phase are of significant interest owing to their potential for scalable and flexible photoelectronic applications. Although various dispersants such as surfactants, oligomers, and polymers are used to obtain highly exfoliated TMD nanosheets, most of them are electrically insulating and need to be removed; otherwise, the photoelectric properties of the TMD nanosheets degrade. Here, inorganic halide perovskite nanocrystals (NCs) of CsPbX3 (X = Cl, Br, or I) are presented as non-destructive dispersants capable of dispersing TMD nanosheets in the liquid phase and enhancing the photodetection properties of the nanosheets, thus eliminating the need to remove the dispersant. MoSe2 nanosheets dispersed in the liquid phase are adsorbed with CsPbCl3 NCs. The CsPbCl3 nanocrystals on MoSe2 efficiently withdraw electrons from the nanosheets, and suppress the dark current of the MoSe2 nanosheets, leading to flexible near-infrared MoSe2 photodetectors with a high ON/OFF photocurrent ratio and detectivity. Moreover, lanthanide ion-doped CsPbCl3 NCs enhance the ON/OFF current ratio to >106 . Meanwhile, the dispersion stability of the MoSe2 nanosheets exfoliated with the perovskite NCs is sufficiently high.
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Affiliation(s)
- Hyeokjung Lee
- Department of Materials Science and Engineering, Yonsei University, Yonsei-ro 50, Seodaemun-gu, Seoul, 03722, Republic of Korea
| | - Hyowon Han
- Department of Materials Science and Engineering, Yonsei University, Yonsei-ro 50, Seodaemun-gu, Seoul, 03722, Republic of Korea
| | - Chanho Park
- Department of Materials Science and Engineering, Yonsei University, Yonsei-ro 50, Seodaemun-gu, Seoul, 03722, Republic of Korea
| | - Jin Woo Oh
- Department of Materials Science and Engineering, Yonsei University, Yonsei-ro 50, Seodaemun-gu, Seoul, 03722, Republic of Korea
| | - Hong Hee Kim
- Center for Opto-Electronic Materials and Devices, Korea Institute of Science and Technology (KIST), Seoul, 02792, Republic of Korea
| | - Sohee Kim
- Department of Materials Science and Engineering, Yonsei University, Yonsei-ro 50, Seodaemun-gu, Seoul, 03722, Republic of Korea
| | - Min Koo
- Department of Materials Science and Engineering, Yonsei University, Yonsei-ro 50, Seodaemun-gu, Seoul, 03722, Republic of Korea
| | - Won Kook Choi
- Center for Opto-Electronic Materials and Devices, Korea Institute of Science and Technology (KIST), Seoul, 02792, Republic of Korea
| | - Cheolmin Park
- Department of Materials Science and Engineering, Yonsei University, Yonsei-ro 50, Seodaemun-gu, Seoul, 03722, Republic of Korea
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Sett S, Parappurath A, Gill NK, Chauhan N, Ghosh A. Engineering sensitivity and spectral range of photodetection in van der Waals materials and hybrids. NANO EXPRESS 2022. [DOI: 10.1088/2632-959x/ac46b9] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Abstract
Exploration of van der Waals heterostructures in the field of optoelectronics has produced photodetectors with very high bandwidth as well as ultra-high sensitivity. Appropriate engineering of these heterostructures allows us to exploit multiple light-to-electricity conversion mechanisms, ranging from photovoltaic, photoconductive to photogating processes. These mechanisms manifest in different sensitivity and speed of photoresponse. In addition, integrating graphene-based hybrid structures with photonic platforms provides a high gain-bandwidth product, with bandwidths ≫1 GHz. In this review, we discuss the progression in the field of photodetection in 2D hybrids. We emphasize the physical mechanisms at play in diverse architectures and discuss the origin of enhanced photoresponse in hybrids. Recent developments in 2D photodetectors based on room temperature detection, photon-counting ability, integration with Si and other pressing issues, that need to be addressed for these materials to be integrated with industrial standards have been discussed.
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Erdewyk MV, Sambur JB. Single Nanoflake Photoelectrochemistry Reveals Intrananoflake Doping Heterogeneity That Explains Ensemble-Level Photoelectrochemical Behavior. ACS APPLIED MATERIALS & INTERFACES 2021; 14:22737-22746. [PMID: 34723470 DOI: 10.1021/acsami.1c14928] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Transition metal dichalcogenide (TMD) nanoflake thin films are attractive electrode materials for photoelectrochemical (PEC) solar energy conversion and sensing applications, but their photocurrent quantum yields are generally lower than those of bulk TMD electrodes. The poor PEC performance has been primarily attributed to enhanced charge carrier recombination at exposed defect and edge sites introduced by the exfoliation process. Here, a single nanoflake PEC approach reveals how an alternative effect, doping heterogeneity, limits ensemble-level PEC performance. Photocurrent mapping and local photocurrent-potential (i-E) measurements of MoS2 nanoflakes exfoliated from naturally occurring bulk crystals revealed the presence of n- and p-type domains within the same nanoflake. Interestingly, the n- and p-type domains in the natural MoS2 nanoflakes were equally efficient for iodide oxidation and tri-iodide reduction (IQE values exceed 80%). At the single domain-level, the natural MoS2 nanoflakes were nearly as efficient as nanoflakes exfoliated from synthetic n-type MoS2 crystals. Single domain-level i-E measurements explain why natural MoS2 nanoflakes exhibit an n-type to p-type photocurrent switching effect in ensemble-level measurements: the n- and p-type diode currents from individual domains oppose each other upon illuminating the entire nanoflake, resulting in zero photocurrent at the switching potential. The doping heterogeneity effect is likely due to nonideal stoichiometry, where p-type domains are S-rich according to XPS measurements. Although this doping heterogeneity effect limits photoanode or photocathode performance, these findings open the possibility to synthesize efficient TMD nanoflake photocatalysts with well-defined lateral p- and n-type domains for enhanced charge separation.
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Affiliation(s)
- Michael Van Erdewyk
- Department of Chemistry, Colorado State University, 200 West Lake Street, Fort Collins, Colorado 80523-1872, United States
| | - Justin B Sambur
- Department of Chemistry, Colorado State University, 200 West Lake Street, Fort Collins, Colorado 80523-1872, United States
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8
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Chang YP, Li WB, Yang YC, Lu HL, Lin MF, Chiu PW, Lin KI. Oxidation and Degradation of WS 2 Monolayers Grown by NaCl-Assisted Chemical Vapor Deposition: Mechanism and Prevention. NANOSCALE 2021; 13:16629-16640. [PMID: 34586136 DOI: 10.1039/d1nr04809k] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
The preservation of two-dimensional WS2 in the environment is a concern for researchers. In addition to water vapor and oxygen, the latest research points out that degradation is directly related to light absorption. Based on the selection rules of nonlinear optics, two-photon absorption is dipole forbidden in the exciton 1s states, but second-harmonic generation (SHG) is allowed with virtual transitions. According to this mechanism, we proved that SHG is an optical detection method with non-photooxidative damage and energy characteristics. With this detection method, we can explore the oxidation and degradation mechanisms of WS2 grown by NaCl-assisted chemical vapor deposition in its original state. The WS2 monolayers that use NaCl to assist in growth have undergone different degradation processes, starting to oxidize from random positions in the triangular flake. We use a photocatalytic reaction to explain the photo-induced degradation mechanism with sulfur vacancies. It was further found that WS2 grown with NaCl assistance is hydrolyzed in a dark and high-humidity environment, which does not occur in pure WS2. Finally, we demonstrated that changing the direction of the sapphire substrate relative to the gas flow direction to grow NaCl-assisted WS2 can greatly improve its stability in the ambient atmosphere, even when exposed to light. The optimal geometric structures and ground state energies are investigated by the density functional theory-based calculations. According to the orientation and symmetry of NaCl-assisted WS2, we can expect that it will have a better growth quality when the gas flow direction is perpendicular to the [112̄0] direction of the sapphire substrate. This contributes to the nucleation and subsequent growth of NaCl-assisted WS2. This research provides a more stable optical inspection method than other established methods and greatly improves the operational stability of NaCl-assisted WS2 under environmental conditions.
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Affiliation(s)
- Yao-Pang Chang
- Department of Electrical Engineering, National Tsing Hua University, Hsinchu 30013, Taiwan.
| | - Wei-Bang Li
- Core Facility Center, National Cheng Kung University, Tainan 70101, Taiwan.
- Department of Physics, National Cheng Kung University, Tainan 70101, Taiwan
| | - Yueh-Chiang Yang
- Department of Electrical Engineering, National Tsing Hua University, Hsinchu 30013, Taiwan.
| | - Hsueh-Lung Lu
- Department of Electrical Engineering, National Tsing Hua University, Hsinchu 30013, Taiwan.
| | - Ming-Fa Lin
- Department of Physics, National Cheng Kung University, Tainan 70101, Taiwan
| | - Po-Wen Chiu
- Department of Electrical Engineering, National Tsing Hua University, Hsinchu 30013, Taiwan.
| | - Kuang-I Lin
- Core Facility Center, National Cheng Kung University, Tainan 70101, Taiwan.
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Ma H, Gosh UK, Ying Y, Long Y. Stochastic Collision Photoelectrochemistry for Light‐Induced Electron Transfer Dynamics. ChemElectroChem 2021. [DOI: 10.1002/celc.202100439] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Affiliation(s)
- Hui Ma
- State Key Laboratory of Analytical Chemistry for Life Science School of Chemistry and Chemical Engineering Nanjing University 163 Xianlin Road Nanjing 210023 P. R. China
| | - Utpal Kumar Gosh
- School of Chemistry & Molecular Engineering East China University of Science and Technology 130 Meilong Road Shanghai 200237 P. R. China
| | - Yi‐Lun Ying
- State Key Laboratory of Analytical Chemistry for Life Science School of Chemistry and Chemical Engineering Nanjing University 163 Xianlin Road Nanjing 210023 P. R. China
- Chemistry and Biomedicine Innovation Center Nanjing University 163 Xianlin Road Nanjing 210023 P. R. China
| | - Yi‐Tao Long
- State Key Laboratory of Analytical Chemistry for Life Science School of Chemistry and Chemical Engineering Nanjing University 163 Xianlin Road Nanjing 210023 P. R. China
- School of Chemistry & Molecular Engineering East China University of Science and Technology 130 Meilong Road Shanghai 200237 P. R. China
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10
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Hill JW, Hill CM. Directly visualizing carrier transport and recombination at individual defects within 2D semiconductors. Chem Sci 2021; 12:5102-5112. [PMID: 34163749 PMCID: PMC8179556 DOI: 10.1039/d0sc07033e] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2020] [Accepted: 02/08/2021] [Indexed: 12/13/2022] Open
Abstract
Two-dimensional semiconductors (2DSCs) are promising materials for a wide range of optoelectronic applications. While the fabrication of 2DSCs with thicknesses down to the monolayer limit has been demonstrated through a variety of routes, a robust understanding of carrier transport within these materials is needed to guide the rational design of improved practical devices. In particular, the influence of different types of structural defects on transport is critical, but difficult to interrogate experimentally. Here, a new approach to visualizing carrier transport within 2DSCs, Carrier Generation-Tip Collection Scanning Electrochemical Cell Microscopy (CG-TC SECCM), is described which is capable of providing information at the single-defect level. In this approach, carriers are locally generated within a material using a focused light source and detected as they drive photoelectrochemical reactions at a spatially-offset electrolyte interface created through contact with a pipet-based probe, allowing carrier transport across well-defined, µm-scale paths within a material to be directly interrogated. The efficacy of this approach is demonstrated through studies of minority carrier transport within mechanically-exfoliated n-type WSe2 nanosheets. CG-TC SECCM imaging experiments carried out within pristine basal planes revealed highly anisotropic hole transport, with in-plane and out-of-plane hole diffusion lengths of 2.8 µm and 5.8 nm, respectively. Experiments were also carried out to probe recombination across individual step edge defects within n-WSe2 which suggest a significant surface charge (∼5 mC m-2) exists at these defects, significantly influencing carrier transport. Together, these studies demonstrate a powerful new approach to visualizing carrier transport and recombination within 2DSCs, down to the single-defect level.
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Affiliation(s)
- Joshua W Hill
- Department of Chemistry, University of Wyoming, 1000 E University Ave Laramie WY 82071 USA
| | - Caleb M Hill
- Department of Chemistry, University of Wyoming, 1000 E University Ave Laramie WY 82071 USA
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Zheng SW, Wang HY, Wang L, Wang H, Sun HB. Layer-Dependent Electron Transfer and Recombination Processes in MoS 2/WSe 2 Multilayer Heterostructures. J Phys Chem Lett 2020; 11:9649-9655. [PMID: 33125851 DOI: 10.1021/acs.jpclett.0c02952] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Understanding and controlling the charge transfer processes of two-dimensional (2D) materials are fundamental for the optimized device performance based on 2D semiconductors and heterostructures. The charge transfer rate is very robust in transition metal disulfide (TMD) heterostructures with type II band alignments, which can be manipulated by intercalating a dielectric layer like hBN to isolate the donor and acceptor monolayers. This study shows that there is an alternative way to change the electron transfer and recombination rates in the case of nLMoS2/mLWSe2 multilayer heterostructures, where the donor-acceptor distance is maintained, but the rate of electron transfer is strongly layer dependent and shows asymmetry for the layer number of donor and acceptor monolayers. Especially, the 1LMoS2/2LWSe2 heterostructure slows electron transfer and charge recombination rates ∼2.3 and ∼12 times that of the 1LMoS2/1LWSe2 heterostructure, respectively, which have been competitive with that in the 1LMoS2/hBN/1LWSe2 heterostructure. From an application perspective, the noninterfacial electron transfer in which photogenerated electrons should across more than one atomically thin layer is not favorable due to the built-in electric field established by the initial interfacial electron transfer.
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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
| | - Hai-Yu 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 Wang
- 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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Mao H, Fu Y, Yang H, Deng ZZ, Sun Y, Liu D, Wu Q, Ma T, Song XM. Ultrathin 1T-MoS 2 Nanoplates Induced by Quaternary Ammonium-Type Ionic Liquids on Polypyrrole/Graphene Oxide Nanosheets and Its Irreversible Crystal Phase Transition During Electrocatalytic Nitrogen Reduction. ACS APPLIED MATERIALS & INTERFACES 2020; 12:25189-25199. [PMID: 32372649 DOI: 10.1021/acsami.0c05204] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Ultrathin nanoplates of metastable 1T-MoS2 have been successfully stabilized and uniformly distributed on the surface of n-butyl triethyl ammonium bromide functionalized polypyrrole/graphene oxide (BTAB/PPy/GO) by a very simple hydrothermal method. BTAB as a typical kind of quaternary ammonium-type ionic liquids (ILs) played a crucial role in the formation of the obtained 1T-MoS2/BTAB/PPy/GO. It was covalently linked with PPy/GO and arranged in a highly ordered order at the solid-liquid interface of PPy/GO and H2O due to Coulombic interactions and other intermolecular interactions, which would induce and stabilize ultrathin 1T-MoS2 nanoplates by morphosynthesis. The good electrocatalytic activity toward nitrogen reduction reaction (NRR) with strong durability and good stability can be achieved by 1T-MoS2/BTAB/PPy/GO due to their excellent inorganic/organic hierarchical lamellar micro-/nanostructures. Especially, after the long-term electrocatalysis for NRR at a negative potential, metastable 1T-MoS2 as the catalytic center undergoes two types of irreversible crystal phase transition, which was converted to 1T'-MoS2 and Mo2N, caused by the competitive hydrogen evolution reaction (HER) process and the electrochemical reaction between the electroactive 1T-MoS2 and N2, respectively. The new N-Mo bonding prevents Mo atoms from binding to other N atoms in N2, resulting in the deactivation of the electrocatalysts to NRR after being used for 18 h. Even so, quaternary ammonium-type ILs would induce the crystal structures of transition-metal dichalcogenides (TMDCs), which might provide a new thought for the reasonable design of electrocatalysts based on TMDCs for electrocatalysis.
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Affiliation(s)
- Hui Mao
- Institute of Clean Energy Chemistry, Key Laboratory for Green Synthesis and Preparative Chemistry of Advanced Materials, College of Chemistry, Liaoning University, Shenyang 110036, China
| | - Yuanlin Fu
- Institute of Clean Energy Chemistry, Key Laboratory for Green Synthesis and Preparative Chemistry of Advanced Materials, College of Chemistry, Liaoning University, Shenyang 110036, China
| | - Haoran Yang
- Institute of Clean Energy Chemistry, Key Laboratory for Green Synthesis and Preparative Chemistry of Advanced Materials, College of Chemistry, Liaoning University, Shenyang 110036, China
| | - Zi-Zhao Deng
- Institute of Clean Energy Chemistry, Key Laboratory for Green Synthesis and Preparative Chemistry of Advanced Materials, College of Chemistry, Liaoning University, Shenyang 110036, China
| | - Ying Sun
- Institute of Clean Energy Chemistry, Key Laboratory for Green Synthesis and Preparative Chemistry of Advanced Materials, College of Chemistry, Liaoning University, Shenyang 110036, China
| | - Daliang Liu
- Institute of Clean Energy Chemistry, Key Laboratory for Green Synthesis and Preparative Chemistry of Advanced Materials, College of Chemistry, Liaoning University, Shenyang 110036, China
| | - Qiong Wu
- Institute of Clean Energy Chemistry, Key Laboratory for Green Synthesis and Preparative Chemistry of Advanced Materials, College of Chemistry, Liaoning University, Shenyang 110036, China
| | - Tianyi Ma
- Discipline of Chemistry, The University of Newcastle, Callaghan, NSW 2308, Australia
| | - Xi-Ming Song
- Institute of Clean Energy Chemistry, Key Laboratory for Green Synthesis and Preparative Chemistry of Advanced Materials, College of Chemistry, Liaoning University, Shenyang 110036, China
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Liu X, Gao P, Hu W, Yang J. Photogenerated-Carrier Separation and Transfer in Two-Dimensional Janus Transition Metal Dichalcogenides and Graphene van der Waals Sandwich Heterojunction Photovoltaic Cells. J Phys Chem Lett 2020; 11:4070-4079. [PMID: 32354217 DOI: 10.1021/acs.jpclett.0c00706] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Two-dimensional (2D) Janus transition metal dichalcogenides (JTMDs) show direct band gaps and strong visible light absorption with promising applications in photovoltaic cells. Here, we investigate the electronic structures and dynamics of photogenerated carriers in 2D JTMDs and graphene van der Waals sandwich heterojunction (G/JTMDs/G) photovoltaic cells by using first-principles calculations. We find that the intrinsic built-in electric field in JTMDs results in an asymmetry potential, which can be used to effectively enhance the separation and transfer of photogenerated carriers from JTMDs to different graphene layers with a preferred direction within hundreds of femtoseconds in the G/JTMDs/G heterostructures. Furthermore, the photogenerated electrons (holes) can be transferred from monolayer MoSSe (MoSeTe) to the graphene sheets by the Se side with a lower (higher) potential, while the transfer of the photogenerated holes (electrons) is prohibited due to the large separation between the donor and acceptor states.
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Affiliation(s)
- Xiaofeng Liu
- Hefei National Laboratory for Physical Sciences at the Microscale, Department of Chemical Physics, and Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Pengfei Gao
- Hefei National Laboratory for Physical Sciences at the Microscale, Department of Chemical Physics, and Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Wei Hu
- Hefei National Laboratory for Physical Sciences at the Microscale, Department of Chemical Physics, and Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Jinlong Yang
- Hefei National Laboratory for Physical Sciences at the Microscale, Department of Chemical Physics, and Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
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Wang L, Nilsson ZN, Tahir M, Chen H, Sambur JB. Influence of the Substrate on the Optical and Photo-electrochemical Properties of Monolayer MoS 2. ACS APPLIED MATERIALS & INTERFACES 2020; 12:15034-15042. [PMID: 32141285 DOI: 10.1021/acsami.9b21230] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Substrates influence the electrical and optical properties of monolayer (ML) MoS2 in field-effect transistors and photodetectors. Photoluminescence (PL) and Raman spectroscopy measurements have shown that conducting substrates can vary the doping concentration and influence exciton decay channels in ML-MoS2. Doping and exciton decay dynamics are expected to play a major role in the efficiency of light-driven chemical reactions, but it is unclear to what extent these factors contribute to the photo(electro)catalytic properties of ML-MoS2. Here, we report spatially resolved PL, Raman, and photo-electrochemical current measurements of 5-10 μm-wide ML-MoS2 triangles deposited on pairs of indium-doped tin oxide (ITO) electrodes that are separated by a narrow insulating quartz channel [i.e., an ITO interdigitated array (IDA) electrode]. Optical microscopy images and atomic force microscopy measurements revealed that the ML-MoS2 triangles lie conformally on the quartz and ITO substrates. The PL spectrum of MoS2 shifts and decreases in intensity in the ITO region, which can be attributed to differences in nonradiative and radiative exciton decay channels. Raman spectra showed no significant peak shifts on the two substrates that would have indicated a substrate-induced doping effect. We spatially resolved the photo-electrochemical current because of hole-induced iodide oxidation and observed that ML-MoS2 produces lower photocurrents in the quartz region than in the ITO region. The correlated PL, Raman, and photocurrent mapping data show that the MoS2/quartz interface diminishes fast nonradiative exciton decay pathways but the photocurrent response in the quartz region is likely limited by inefficient in-plane carrier transport to the ITO electrode because of carrier recombination with S vacancies in MoS2 or charged impurities in the quartz substrate. Nonetheless, the experimental methodology presented herein provides a framework to evaluate substrate engineering strategies to tune the (photo)electrocatalytic properties of two-dimensional materials.
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Affiliation(s)
- Li Wang
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523, United States
| | - Zach N Nilsson
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523, United States
| | - Muhammad Tahir
- Department of Physics, Colorado State University, Fort Collins, Colorado 80523, United States
| | - Hua Chen
- Department of Physics, Colorado State University, Fort Collins, Colorado 80523, United States
- School of Advanced Materials Discovery (SAMD), Colorado State University, Fort Collins, Colorado 80523, United States
| | - Justin B Sambur
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523, United States
- School of Advanced Materials Discovery (SAMD), Colorado State University, Fort Collins, Colorado 80523, United States
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Zhang L, Mu L, Zhou Q, Hu X. Solar-assisted fabrication of dimpled 2H-MoS 2 membrane for highly efficient water desalination. WATER RESEARCH 2020; 170:115367. [PMID: 31838365 DOI: 10.1016/j.watres.2019.115367] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/06/2019] [Revised: 10/18/2019] [Accepted: 12/01/2019] [Indexed: 06/10/2023]
Abstract
Solar-driven evaporation has been proposed as an efficient way to harvest solar energy for water treatment and desalination. However, the complex preparation process and the degradation of photothermal absorbers restrict their practical applications in solar thermal technology. Herein, a solar-assisted fabrication of three-dimensional dimpled MoS2 membrane (DMM-SA) with an open macroporous (1-2 μm) network is fabricated by folding and overlapping nanosheets under solar illumination. DMM-SA exhibits superior water permeability (334-461 LMH/bar) and extraordinary chemical and structural stability. Compared to the 1T and mixed-phase DMM-SA samples, 2H-DMM-SA floating on the water surface generates high heat localization and achieves high evaporation efficiencies of 83.8 ± 0.8% and 91.5 ± 1.1% at 1 and 3 sun illumination, respectively. After multiple illumination and regeneration cycles, 2H-DMM-SA presents high water evaporation and salt rejection performance. After desalination, the salinity level of permeate water is far below the World Health Organization (WHO) standard. Numerical simulations verify that the inner spaces between two nanosheets and the nanochannels contribute to the high bulk water and vapor fluxes during desalination. The facile and efficient design of 3D 2H-DMM-SA provides a novel avenue for seawater utilization by harvesting solar energy.
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Affiliation(s)
- Lei Zhang
- Key Laboratory of Pollution Processes and Environmental Criteria (Ministry of Education)/Tianjin Key Laboratory of Environmental Remediation and Pollution Control, College of Environmental Science and Engineering, Nankai University, Tianjin, 300350, China
| | - Li Mu
- Key Laboratory for Environmental Factors Control of Agro-Product Quality Safety (Ministry of Agriculture and Rural Affairs), Tianjin Key Laboratory of Agro-Environment and Safe-Product, Agro-environmental Protection Institute, Ministry of Agriculture and Rural Affairs, Tianjin, 300191, China
| | - Qixing Zhou
- Key Laboratory of Pollution Processes and Environmental Criteria (Ministry of Education)/Tianjin Key Laboratory of Environmental Remediation and Pollution Control, College of Environmental Science and Engineering, Nankai University, Tianjin, 300350, China
| | - Xiangang Hu
- Key Laboratory of Pollution Processes and Environmental Criteria (Ministry of Education)/Tianjin Key Laboratory of Environmental Remediation and Pollution Control, College of Environmental Science and Engineering, Nankai University, Tianjin, 300350, China.
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Wang L, Tahir M, Chen H, Sambur JB. Probing Charge Carrier Transport and Recombination Pathways in Monolayer MoS 2/WS 2 Heterojunction Photoelectrodes. NANO LETTERS 2019; 19:9084-9094. [PMID: 31738855 DOI: 10.1021/acs.nanolett.9b04209] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Monolayer heterojunctions such as MoS2/WS2 are attractive for solar energy conversion applications because the interfacial electric field spatially separates charge carriers in less than 100 fs. Photoelectrochemical cells represent an intriguing platform to collect the spatially separated carriers. However, the recombination, transport, and interfacial charge transfer processes that take place following the ultrafast charge separation step have not been investigated. Here we demonstrate novel charge recombination and transport pathways in monolayer MoS2/WS2 photoelectrochemical cells by spatially resolving the net collection of carriers (i.e., the photocurrent) at the single nanosheet level. We discovered an excitation-wavelength-dependent recombination pathway that depends on the heterojunction stacking configuration and the carrier generation profile in the heterostructure. Photocurrent mapping measurements revealed that charge transport occurs parallel to the layers over micrometer-scale distances even though the indium tin oxide electrode and liquid electrolyte provide efficient charge extraction pathways via intimate electron- and hole-selective contacts. Our results reveal how composition heterogeneity influences the performance of bulk heterojunction electrodes made from randomly oriented nanosheets and provide critical insight into the design of efficient heterojunction photoelectrodes for solar energy conversion applications.
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Wang L, Schmid M, Sambur JB. Single nanoparticle photoelectrochemistry: What is next? J Chem Phys 2019; 151:180901. [PMID: 31731844 DOI: 10.1063/1.5124710] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Semiconductor photoelectrochemistry is a fascinating field that deals with the chemistry and physics of photodriven reactions at solid/liquid interfaces. The interdisciplinary field attracts (electro)chemists, materials scientists, spectroscopists, and theorists to study fundamental and applied problems such as carrier dynamics at illuminated electrode/electrolyte interfaces and solar energy conversion to electricity or chemical fuels. In the pursuit of practical photoelectrochemical energy conversion systems, researchers are exploring inexpensive, solution-processed semiconductor nanomaterials as light absorbers. Harnessing the enormous potential of nanomaterials for energy conversion applications requires a fundamental understanding of charge carrier generation, separation, transport, and interfacial charge transfer at heterogeneous nanoscale interfaces. Our current understanding of these processes is derived mainly from ensemble-average measurements of nanoparticle electrodes that report on the average behavior of trillions of nanoparticles. Ensemble-average measurements conceal how nanoparticle heterogeneity (e.g., differences in particle size, shape, and surface structure) contributes to the overall photoelectrochemical response. This perspective article focuses on the emerging area of single particle photoelectrochemistry, which has opened up an exciting new frontier: direct investigations of photodriven reactions on individual nanomaterials, with the ability to elucidate the role of particle-dependent properties on the photoelectrochemical behavior. Here, we (1) review the basic principles of photoelectrochemical cells, (2) point out the potential advantages and differences between bulk and nanoelectrodes, (3) introduce approaches to single nanoparticle photoelectrochemistry and highlight key findings, and (4) provide our perspective on future research directions.
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Affiliation(s)
- Li Wang
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523, USA
| | - Merranda Schmid
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523, USA
| | - Justin B Sambur
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523, USA
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Hill JW, Hill CM. Directly Mapping Photoelectrochemical Behavior within Individual Transition Metal Dichalcogenide Nanosheets. NANO LETTERS 2019; 19:5710-5716. [PMID: 31287956 DOI: 10.1021/acs.nanolett.9b02336] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Spatial variations in photoelectrochemical reaction rates within individual p-type WSe2 nanosheets were mapped through the application of scanning electrochemical cell microscopy (SECCM). The simultaneous topographical and electrochemical information provided via SECCM directly revealed how both sheet thickness and the presence of defect structures affect the local rate of photoelectrochemical reactions for both outer sphere and inner sphere redox couples. Sheet thickness was found to play a dramatic role in reaction rates, with onset potentials shifting by as much as 0.5 V over thicknesses of 20-120 nm, attributable to the inability of thin sheets to support independent space charge layers. Step/edge features were found to play a detrimental role for the outer sphere redox couple investigated (Ru(NH3)63+ reduction), with taller steps having larger effects on performance. Shorter step features were found to be beneficial for hydrogen evolution, showing a controlled density of defect features is desirable for inner sphere processes. The studies presented here not only provide valuable, quantitative insights into the behavior of transitional metal dichalcogenide materials but also demonstrate the power of applying SECCM to the study of photoelectrochemical systems, particularly those involving two-dimensional (2D) materials.
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Affiliation(s)
- Joshua W Hill
- Department of Chemistry , University of Wyoming , 1000 E. University Ave , Laramie , Wyoming 82071 , United States
| | - Caleb M Hill
- Department of Chemistry , University of Wyoming , 1000 E. University Ave , Laramie , Wyoming 82071 , United States
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Wang L, Schmid M, Nilsson ZN, Tahir M, Chen H, Sambur JB. Laser Annealing Improves the Photoelectrochemical Activity of Ultrathin MoSe 2 Photoelectrodes. ACS APPLIED MATERIALS & INTERFACES 2019; 11:19207-19217. [PMID: 31070890 DOI: 10.1021/acsami.9b04785] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Understanding light-matter interactions in transition-metal dichalcogenides (TMDs) is critical for optoelectronic device applications. Several studies have shown that high intensity light irradiation can tune the optical and physical properties of pristine TMDs. The enhancement in optoelectronic properties has been attributed to a so-called laser annealing effect that heals chalcogen vacancies. However, it is unknown whether laser annealing improves functional properties such as photocatalytic activity. Here, we show that high intensity supra band gap illumination improves the photoelectrochemical activity of MoSe2 nanosheets for iodide oxidation in indium doped tin oxide/MoSe2/I-, I3-/Pt liquid junction solar cells. Ensemble-level photoelectrochemical measurements show that, on average, illuminating MoSe2 thin films with 1 W/cm2 532 nm excitation increases the photoelectrochemical current by 142% and shifts the photocurrent response to more favorable (negative) potentials. Scanning photoelectrochemical microscopy measurements reveal that pristine bilayer (2L)-MoSe2, trilayer (3L)-MoSe2, and multilayer-thick nanosheets are initially inactive for iodide oxidation. The light treatment activates 2L-MoSe2 and 3L-MoSe2 materials, and the activation process initiates at the edge sites. The photocurrent enhancement is more significant for 2L-MoSe2 than for 1L-MoSe2. Multilayer-thick MoSe2 remains inactive for iodide oxidation even after the laser treatment. Our microscopy measurements reveal that the laser-induced enhancement effect depends critically on MoSe2 layer thickness. X-ray photoelectron spectroscopy measurements further show that the laser treatment oxidizes Mo(IV) species that are initially associated with Se vacancies. Ambient oxygen fills the Se vacancies and removes trap states, thereby increasing the overall photogenerated carrier collection efficiency. To the best of our knowledge, this work represents the first report on using laser to enhance the photoelectrocatalytic properties of few-layer-thick TMDs. The simple and rapid laser annealing procedure is a promising strategy to tune the reactivity of TMD-based photoelectrochemical cells for electricity and chemical fuel production.
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