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

Moss, B., Wang, Q., Butler, K. T., Grau-Crespo, R. ORCID: https://orcid.org/0000-0001-8845-1719, Selim, S., Regoutz, A., Hisatomi, T., Godin, R., Payne, D. J., Katizas, A. G., Domen, K., Steir, L. and Durrant, J. R. (2021) Linking in-situ charge accumulation to electronic structure in doped SrTiO3 reveals design principles for hydrogen evolving photocatalysts. Nature Materials, 20. pp. 511-517. ISSN 1476-1122 doi: 10.1038/s41563-020-00868-2

Abstract/Summary

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.

Item Type	Article
URI	https://reading-clone.eprints-hosting.org/id/eprint/93917
Identification Number/DOI	10.1038/s41563-020-00868-2
Refereed	Yes
Divisions	Life Sciences > School of Chemistry, Food and Pharmacy > Department of Chemistry
Uncontrolled Keywords	Photocatalysis, SrTiO3
Publisher	Nature Publishing Group
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