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A scanning probe investigation of the role of surface motifs in the behavior of p-WSe_2 photocathodes

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. (2016) A scanning probe investigation of the role of surface motifs in the behavior of p-WSe_2 photocathodes. Energy and Environmental Science, 9 (1). pp. 164-175. ISSN 1754-5692. https://resolver.caltech.edu/CaltechAUTHORS:20151109-102020642

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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-WSe_2 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 Φ_(ext) 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. 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.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1039/C5EE02530C DOIArticle
http://pubs.rsc.org/en/Content/ArticleLanding/2015/EE/c5ee02530cPublisherArticle
ORCID:
AuthorORCID
John, Jimmy0000-0002-8772-8939
Zhou, Xinghao0000-0001-9229-7670
Ardo, Shane0000-0001-7162-6826
Soriaga, Manuel P.0000-0002-0077-6226
Brunschwig, Bruce S.0000-0002-6135-6727
Lewis, Nathan S.0000-0001-5245-0538
Additional Information:© 2016 Royal Society of Chemistry. Received 17 Aug 2015, Accepted 08 Oct 2015. First published online 08 Oct 2015. This material is based upon work performed by the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, supported through the Office of Science of the U.S. Department of Energy under Award No. DE-SC0004993. Additional support for this work was provided by BP. JMV acknowledges support through an NRC Ford Foundation Postdoctoral Fellowship and the U.S. Department of Energy under Award No. DE-SC0004993. JJ thanks the Camille and Henry Dreyfus Foundation for financial support through its postdoctoral fellowship program in environmental chemistry and the U.S. Department of Energy, Office of Basic Energy Sciences under Award No. DE-FG02-03ER15483. DVE acknowledges support from the NIST NRC Fellowship program. JMV, JJ, and DVE also acknowledge the NIST Center for Nanoscale Science and Technology for use of its facilities for some SPCM measurements. SA acknowledges support from a United States Department of Energy, Office of Energy Efficiency and Renewable Energy (EERE) Postdoctoral Research Award under the EERE Fuel Cell Technologies Program. Certain commercial equipment, instruments, and materials are identified in this paper to foster understanding. Such identification does not imply recommendation or endorsement by the National Institute of Standards and Technology, nor does it imply that the materials or equipment identified are the best available for the purpose.
Group:JCAP
Funders:
Funding AgencyGrant Number
Department of Energy (DOE)DE-SC0004993
Ford FoundationUNSPECIFIED
Camille and Henry Dreyfus FoundationUNSPECIFIED
Department of Energy (DOE)DE-FG02-03ER15483
National Research CouncilUNSPECIFIED
BPUNSPECIFIED
EERE Fuel Cell Technologies ProgramUNSPECIFIED
National Institute of Standards and Technology (NIST)UNSPECIFIED
Issue or Number:1
Record Number:CaltechAUTHORS:20151109-102020642
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20151109-102020642
Official Citation:A scanning probe investigation of the role of surface motifs in the behavior of p-WSe2 photocathodes Jesus M. Velazquez, Jimmy John, Daniel V. Esposito, Adam Pieterick, Ragip Pala, Guofeng Sun, Xinghao Zhou, Zhuangqun Huang, Shane Ardo, Manuel P. Soriaga, Bruce S. Brunschwig and Nathan S. Lewis Energy Environ. Sci., 2016, 9, 164-175 DOI: 10.1039/C5EE02530C
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:61987
Collection:CaltechAUTHORS
Deposited By: Ruth Sustaita
Deposited On:09 Nov 2015 19:23
Last Modified:09 Oct 2019 04:22

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