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Published July 5, 2016 | Published + Supplemental Material
Journal Article Open

Mechanistic insights into chemical and photochemical transformations of bismuth vanadate photoanodes

Abstract

Artificial photosynthesis relies on the availability of semiconductors that are chemically stable and can efficiently capture solar energy. Although metal oxide semiconductors have been investigated for their promise to resist oxidative attack, materials in this class can suffer from chemical and photochemical instability. Here we present a methodology for evaluating corrosion mechanisms and apply it to bismuth vanadate, a state-of-the-art photoanode. Analysis of changing morphology and composition under solar water splitting conditions reveals chemical instabilities that are not predicted from thermodynamic considerations of stable solid oxide phases, as represented by the Pourbaix diagram for the system. Computational modelling indicates that photoexcited charge carriers accumulated at the surface destabilize the lattice, and that self-passivation by formation of a chemically stable surface phase is kinetically hindered. Although chemical stability of metal oxides cannot be assumed, insight into corrosion mechanisms aids development of protection strategies and discovery of semiconductors with improved stability.

Additional Information

© 2016 Macmillan Publishers Limited. This work is licensed under a Creative Commons Attribution 4.0 International License. The images or other third party material in this article are included in the article's Creative Commons license, unless indicated otherwise in the credit line; if the material is not included under the Creative Commons license, users will need to obtain permission from the license holder to reproduce the material. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/. Received 01 January 2016; Accepted 20 May 2016; Published 05 July 2016. This study is based on work performed at 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 Number DE-SC0004993. Imaging work at the Molecular Foundry was supported by the Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy under contract number DE-AC02-05CH11231. The EC-AFM part of this work was supported in part by the Laboratory Directed Research and Development Program of Lawrence Berkeley National Laboratory under U.S. Department of Energy contract number DE-AC02-05CH11231. V.K. and F.M.T. acknowledge support from the BaCaTeC programme, project number 2015-1. Craig Jones from Agilent Technologies, Inc. is greatly acknowledged for his help with ICP-MS measurements. Author contributions: F.M.T., F.A.H. and I.D.S. conceived of and designed this study. F.M.T., J.K.C., V.K., M.T.M., D.L., C.A., J.W.B. and I.D.S. performed the experiments. F.M.T., J.K.C., N.J.B., K.M.Y., J. Yang, F.A.H. and I.D.S. analysed and interpreted the data. J. Yu and K.A.P. performed the theoretical calculations and associated analysis. L.C., M.R.S. and J.S. provided some of the materials used for preliminary testing. All authors contributed to the final version of the manuscript. Competing financial interests: The authors declare no competing financial interests.

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August 20, 2023
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