Cooperative Interactions between Surface Terminations Explain Photocatalytic Water Splitting Activity on SrTiO_{3}

• Published in: PRX Energy Vol. 1; no. 2; p. 023002
• Main Authors: Vidushi Sharma, Benjamin Bein, Amanda Lai, Betül Pamuk, Cyrus E. Dreyer, Marivi Fernández-Serra, Matthew Dawber
• Format: Journal Article
• Language: English
• Published: American Physical Society 01.07.2022
• ISSN: 2768-5608
• DOI: 10.1103/PRXEnergy.1.023002

SrTiO_{3} is a highly efficient photocatalyst for the overall water splitting reaction under UV irradiation. However, an atomic-level understanding of the active surface sites responsible for the oxidation and reduction reactions is still lacking. Here we present a unified experimental and computational account of the photocatalytic activity at the SrO and TiO_{2} terminations of aqueous solvated [001] SrTiO_{3}. Our experimental findings show that the overall water-splitting reaction proceeds on the SrTiO_{3} surface only when the two terminations are simultaneously exposed to water. Our simulations explain this, showing that the photogenerated hole-driven oxidation primarily occurs at SrO surfaces in a sequence of four single hole transfer reactions, while the TiO_{2} termination effects the crucial band alignment of the photocatalyst relative to the water oxidation potential. The present work elucidates the interdependence of the two chemical terminations of SrTiO_{3} surfaces, and has consequent implications for maximizing sustainable solar-driven water splitting.