Linking in situ charge accumulation to electronic structure in doped SrTiO3 reveals design principles for hydrogen-evolving photocatalysts
File(s)
Accepted version
Supporting information
Author(s)
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.
Date Issued
2021-04-01
Date Acceptance
2020-11-03
Citation
Nature Materials, 2021, 20 (4), pp.511-517
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
Commission of the European Communities
Commission of the European Communities
Imperial College London
The Royal Society
Identifier
https://www.nature.com/articles/s41563-020-00868-2
Grant Number
749231
291482
RSG\R1\180434
Subjects
Science & Technology
Physical Sciences
Technology
Chemistry, Physical
Materials Science, Multidisciplinary
Physics, Applied
Physics, Condensed Matter
Chemistry
Materials Science
Physics
Z-SCHEME
METAL-ION
WATER
EFFICIENT
EVOLUTION
TIO2
LA
RECOMBINATION
PHOTOCURRENT
SHEETS
Nanoscience & Nanotechnology
Publication Status
Published
Date Publish Online
2021-01-11