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Linking in situ charge accumulation to electronic structure in doped SrTiO3 reveals design principles for hydrogen-evolving photocatalysts

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Title: Linking in situ charge accumulation to electronic structure in doped SrTiO3 reveals design principles for hydrogen-evolving photocatalysts
Authors: Moss, B
Wang, Q
Butler, K
Grau-Crespo, R
Selim, S
Regoutz, A
Hisatomi, T
Godin, R
Payne, D
Kafizas, A
Domen, K
Steier, L
Durrant, J
Item Type: Journal Article
Abstract: Recently, high solar-to-hydrogen efficiencies were demonstrated using La and Rh co-doped SrTiO3 (La,Rh:SrTiO3) incorporated into a low-cost and scalable Z-scheme device, known as a photocatalyst sheet. However, the unique properties that enable La,Rh:SrTiO3 to support this impressive performance are not fully understood. Combining in situ spectroelectrochemical measurements with density functional theory and photoelectron spectroscopy produces a depletion model of Rh:SrTiO3 and La,Rh:SrTiO3 photocatalyst sheets. This reveals remarkable properties, such as deep flatband potentials (+2 V versus the reversible hydrogen electrode) and a Rh oxidation state dependent reorganization of the electronic structure, involving the loss of a vacant Rh 4d mid-gap state. This reorganization enables Rh:SrTiO3 to be reduced by co-doping without compromising the p-type character. In situ time-resolved spectroscopies show that the electronic structure reorganization induced by Rh reduction controls the electron lifetime in photocatalyst sheets. In Rh:SrTiO3, enhanced lifetimes can only be obtained at negative applied potentials, where the complete Z-scheme operates inefficiently. La co-doping fixes Rh in the 3+ state, which results in long-lived photogenerated electrons even at very positive potentials (+1 V versus the reversible hydrogen electrode), in which both components of the complete device operate effectively. This understanding of the role of co-dopants provides a new insight into the design principles for water-splitting devices based on bandgap-engineered metal oxides.
Issue Date: 1-Apr-2021
Date of Acceptance: 3-Nov-2020
URI: http://hdl.handle.net/10044/1/83393
DOI: 10.1038/s41563-020-00868-2
ISSN: 1476-1122
Publisher: Nature Research
Start Page: 511
End Page: 517
Journal / Book Title: Nature Materials
Volume: 20
Issue: 4
Copyright Statement: © The Author(s), under exclusive licence to Springer Nature Limited 2021. The final publication is available at Springer via https://doi.org/10.1038/s41563-020-00868-2
Sponsor/Funder: Commission of the European Communities
Commission of the European Communities
Imperial College London
The Royal Society
Funder's Grant Number: 749231
Keywords: Science & Technology
Physical Sciences
Chemistry, Physical
Materials Science, Multidisciplinary
Physics, Applied
Physics, Condensed Matter
Materials Science
Nanoscience & Nanotechnology
Publication Status: Published
Online Publication Date: 2021-01-11
Appears in Collections:Materials
Grantham Institute for Climate Change
Faculty of Natural Sciences
Faculty of Engineering