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Investigations of the stability of GaAs for photoelectrochemical H₂ evolution in acidic or alkaline aqueous electrolytes

Yu, Weilai and Richter, Matthias H. and Simonoff, Ethan and Brunschwig, Bruce S. and Lewis, Nathan S. (2021) Investigations of the stability of GaAs for photoelectrochemical H₂ evolution in acidic or alkaline aqueous electrolytes. Journal of Materials Chemistry A, 9 (40). pp. 22958-22972. ISSN 2050-7488. doi:10.1039/d1ta04145b.

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The long-term stability of p-GaAs photocathodes has been investigated for the hydrogen-evolution reaction (HER) in contact with either 1.0 M H₂SO₄(aq) or 1.0 M KOH(aq). Stability for the HER was evaluated using p-GaAs electrodes that were either etched or coated with active HER catalysts (Pt and CoP). Changes in surface characteristics of GaAs after exposure to electrochemical conditions were monitored by X-ray photoelectron spectroscopy (XPS), and electrode dissolution processes were evaluated by inductively coupled plasma mass spectrometry (ICP-MS). Consistent with thermodynamic predictions, after operation of the HER at pH 0 or pH 14, illuminated etched p-GaAs electrodes exhibited minimal dissolution while preserving a nearly stoichiometric surface. Electrodeposition or sputtering of Pt on the p-GaAs surface promoted the formation of excess As⁰ via an interfacial reaction during the HER. The resulting non-stoichiometric As⁰-rich surface of p-GaAs/Pt electrodes caused a loss in photoactivity as well as substantial cathodic dark current. In contrast, p-GaAs electrodes coated with thin-film CoP catalysts did not display an increase in surficial As⁰ after operation of the HER in acidic electrolytes. Minimization of deleterious interfacial reactions is thus critical to obtain extended stability in conjunction with high performance from p-GaAs photocathodes.

Item Type:Article
Related URLs:
URLURL TypeDescription
Yu, Weilai0000-0002-9420-0702
Richter, Matthias H.0000-0003-0091-2045
Simonoff, Ethan0000-0002-2156-8602
Brunschwig, Bruce S.0000-0002-6135-6727
Lewis, Nathan S.0000-0001-5245-0538
Alternate Title:Investigations of the stability of GaAs for photoelectrochemical H2 evolution in acidic or alkaline aqueous electrolytes
Additional Information:© The Royal Society of Chemistry 2021. Submitted 17 May 2021. Accepted 22 Sep 2021. First published 22 Sep 2021. 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 Number DE-SC0004993 and by award DE-SC0022087 from the DOE Office of Basic Energy Sciences. Research was in part performed in the Molecular Materials Resource Center (MMRC) of the Beckman Institute of the California Institute of Technology. Phil Jahelka and Dr Chengxiang Xiang are gratefully acknowledged for fruitful discussions. Dr Nathan Dalleska provided assistance with ICP-MS analysis and Dr Pakpoom Buabthong assisted with XPS analysis. There are no conflicts to declare.
Funding AgencyGrant Number
Department of Energy (DOE)DE-SC0004993
Department of Energy (DOE)DE-SC0022087
Issue or Number:40
Record Number:CaltechAUTHORS:20211008-224606577
Persistent URL:
Official Citation:Investigations of the stability of GaAs for photoelectrochemical H₂ evolution in acidic or alkaline aqueous electrolytes. J. Mater. Chem. A, 2021, 9, 22958-22972; DOI: 10.1039/d1ta04145b
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:111310
Deposited By: George Porter
Deposited On:12 Oct 2021 20:25
Last Modified:26 Oct 2021 16:38

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