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Title: A scanning probe investigation of the role of surface motifs in the behavior of p-WSe 2 photocathodes

Abstract

The spatial variation in the photoelectrochemical performance for the reduction of an aqueous one-electron redox couple, Ru(NH 3) 6 3+/2+, and for the evolution of H 2(g) from 0.5 M H 2SO 4(aq) at the surface of bare or Pt-decorated p-type WSe 2 photocathodes has been investigated in situ using scanning photocurrent microscopy (SPCM). The measurements revealed significant differences in the charge-collection performance (quantified by the values of external quantum yields, Φ ext) on various macroscopic terraces. Local spectral response measurements indicated a variation in the local electronic structure among the terraces, which was consistent with a non-uniform spatial distribution of sub-band-gap states within the crystals. The photoconversion efficiencies of Pt-decorated p-WSe2 photocathodes were greater for the evolution of H 2(g) from 0.5 M H 2SO 4 than for the reduction of Ru(NH 3) 6 3+/2+, and terraces that exhibited relatively low values of Φext for the reduction of Ru(NH 3) 6 3+/2+ could in some cases yield values of Φ ext for the evolution of H 2(g) comparable to the values of Φ ext yielded by the highest-performing terraces. In conclusion, although the spatial resolution of the techniques used in this work frequently did not result in observation ofmore » the effect of edge sites on photocurrent efficiency, some edge effects were observed in the measurements; however the observed edge effects differed among edges, and did not appear to determine the performance of the electrodes.« less

Authors:
 [1]; ORCiD logo [2];  [3];  [4];  [4];  [5];  [4];  [6];  [7];  [5];  [8];  [9]
  1. California Inst. of Technology (CalTech), Pasadena, CA (United States). Division of Chemistry and Chemical Engineering; California Inst. of Technology (CalTech), Pasadena, CA (United States). Joint Center for Artificial Photosynthesis (JCAP)
  2. California Inst. of Technology (CalTech), Pasadena, CA (United States). Division of Chemistry and Chemical Engineering
  3. Columbia Univ., New York, NY (United States). Dept. of Chemical Engineering; National Inst. of Standards and Technology (NIST), Gaithersburg, MD (United States). Center for Neutron Research. Materials Measurement Lab.
  4. California Inst. of Technology (CalTech), Pasadena, CA (United States). Joint Center for Artificial Photosynthesis (JCAP); California Inst. of Technology (CalTech), Pasadena, CA (United States). Division of Engineering and Applied Science
  5. California Inst. of Technology (CalTech), Pasadena, CA (United States). Joint Center for Artificial Photosynthesis (JCAP)
  6. Bruker Nano Surfaces, Goleta, CA (United States)
  7. Univ. of California, Irvine, CA (United States). Dept. of Chemistry and Department of Chemical Engineering and Materials Science
  8. California Inst. of Technology (CalTech), Pasadena, CA (United States). Joint Center for Artificial Photosynthesis (JCAP); California Inst. of Technology (CalTech), Pasadena, CA (United States). Molecular Materials Research Center, Beckman Inst.
  9. California Inst. of Technology (CalTech), Pasadena, CA (United States). Division of Chemistry and Chemical Engineering; California Inst. of Technology (CalTech), Pasadena, CA (United States). Joint Center for Artificial Photosynthesis (JCAP); California Inst. of Technology (CalTech), Pasadena, CA (United States). Molecular Materials Research Center, Beckman Inst.; California Inst. of Technology (CalTech), Pasadena, CA (United States). Kavli Nanoscience Inst.
Publication Date:
Research Org.:
California Inst. of Technology (CalTech), Pasadena, CA (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); USDOE Office of Energy Efficiency and Renewable Energy (EERE), Fuel Cell Technologies Office (EE-3F)
OSTI Identifier:
1436126
Grant/Contract Number:  
SC0004993; FG02-03ER15483
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Energy & Environmental Science
Additional Journal Information:
Journal Volume: 9; Journal Issue: 1; Journal ID: ISSN 1754-5692
Publisher:
Royal Society of Chemistry
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE

Citation Formats

Velazquez, Jesus M., John, Jimmy, Esposito, Daniel V., Pieterick, Adam, Pala, Ragip, Sun, Guofeng, Zhou, Xinghao, Huang, Zhuangqun, Ardo, Shane, Soriaga, Manuel P., Brunschwig, Bruce S., and Lewis, Nathan S. A scanning probe investigation of the role of surface motifs in the behavior of p-WSe2 photocathodes. United States: N. p., 2015. Web. doi:10.1039/c5ee02530c.
Velazquez, Jesus M., John, Jimmy, Esposito, Daniel V., Pieterick, Adam, Pala, Ragip, Sun, Guofeng, Zhou, Xinghao, Huang, Zhuangqun, Ardo, Shane, Soriaga, Manuel P., Brunschwig, Bruce S., & Lewis, Nathan S. A scanning probe investigation of the role of surface motifs in the behavior of p-WSe2 photocathodes. United States. doi:10.1039/c5ee02530c.
Velazquez, Jesus M., John, Jimmy, Esposito, Daniel V., Pieterick, Adam, Pala, Ragip, Sun, Guofeng, Zhou, Xinghao, Huang, Zhuangqun, Ardo, Shane, Soriaga, Manuel P., Brunschwig, Bruce S., and Lewis, Nathan S. Thu . "A scanning probe investigation of the role of surface motifs in the behavior of p-WSe2 photocathodes". United States. doi:10.1039/c5ee02530c. https://www.osti.gov/servlets/purl/1436126.
@article{osti_1436126,
title = {A scanning probe investigation of the role of surface motifs in the behavior of p-WSe2 photocathodes},
author = {Velazquez, Jesus M. and John, Jimmy and Esposito, Daniel V. and Pieterick, Adam and Pala, Ragip and Sun, Guofeng and Zhou, Xinghao and Huang, Zhuangqun and Ardo, Shane and Soriaga, Manuel P. and Brunschwig, Bruce S. and Lewis, Nathan S.},
abstractNote = {The spatial variation in the photoelectrochemical performance for the reduction of an aqueous one-electron redox couple, Ru(NH3)63+/2+, and for the evolution of H2(g) from 0.5 M H2SO4(aq) at the surface of bare or Pt-decorated p-type WSe2 photocathodes has been investigated in situ using scanning photocurrent microscopy (SPCM). The measurements revealed significant differences in the charge-collection performance (quantified by the values of external quantum yields, Φext) on various macroscopic terraces. Local spectral response measurements indicated a variation in the local electronic structure among the terraces, which was consistent with a non-uniform spatial distribution of sub-band-gap states within the crystals. The photoconversion efficiencies of Pt-decorated p-WSe2 photocathodes were greater for the evolution of H2(g) from 0.5 M H2SO4 than for the reduction of Ru(NH3)63+/2+, and terraces that exhibited relatively low values of Φext for the reduction of Ru(NH3)63+/2+ could in some cases yield values of Φext for the evolution of H2(g) comparable to the values of Φext yielded by the highest-performing terraces. In conclusion, although the spatial resolution of the techniques used in this work frequently did not result in observation of the effect of edge sites on photocurrent efficiency, some edge effects were observed in the measurements; however the observed edge effects differed among edges, and did not appear to determine the performance of the electrodes.},
doi = {10.1039/c5ee02530c},
journal = {Energy & Environmental Science},
issn = {1754-5692},
number = 1,
volume = 9,
place = {United States},
year = {2015},
month = {10}
}

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Works referenced in this record:

Solar Water Splitting Cells
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