Charge transport in single particle SrTiO3 photocatalysts for water splitting

Brian Zutter; Zejie Chen; Luisa Barrera; Aliya Lapp; Akihiko Kudo; Dan Esposito; Rohini Bala Chandran; Shane Ardo; A. Alec Talin

doi:10.1117/12.2636984

3 October 2022 Charge transport in single particle SrTiO₃ photocatalysts for water splitting

Brian Zutter, Zejie Chen, Luisa Barrera, Aliya Lapp, Akihiko Kudo, Dan Esposito, Rohini Bala Chandran, Shane Ardo, A. Alec Talin

Author Affiliations +

Proceedings Volume PC12200, Low-Dimensional Materials and Devices 2022; PC122000A (2022) https://doi.org/10.1117/12.2636984
Event: SPIE Nanoscience + Engineering, 2022, San Diego, California, United States

Abstract

Solar-powered photochemical water splitting using suspensions of photocatalyst nanoparticles is an attractive route for economical production of green hydrogen. SrTiO3 based photocatalysts have been intensely investigated due to their stability and recently demonstrated near-100% external quantum yield at wavelengths below 400 nm. To extend the optical absorption into the visible range, SrTiO3 nanoparticles can be alloyed with various transition metals. Here we demonstrate that alloying SrTiO3 nanoparticles with ~1% Rh introduces mid-gap recombination centers that degrade the photocarrier lifetime from ~90 ps to ~1 ps, and lower the maximum achievable external quantum yield by an order of magnitude. By trapping the free conduction band electrons normally introduced by oxygen vacancies, Rh-induced traps change the charge transport mechanism from band to trap-mediated space-charge limited conduction, and drastically reduce the built-in electric fields needed for charge separation. Our results illustrate why and how the solar to hydrogen efficiency of Rh-doped SrTiO3 nanoparticles remains low despite extended optical absorption. Furthermore, the absence of built-in fields within Rh doped SrTiO3 nanoparticles suggests a new mechanism for photocatalytic reactions, where modest e-h separation can be achieved with a difference in mobility between electrons and holes.

Conference Presentation

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Brian Zutter, Zejie Chen, Luisa Barrera, Aliya Lapp, Akihiko Kudo, Dan Esposito, Rohini Bala Chandran, Shane Ardo, and A. Alec Talin "Charge transport in single particle SrTiO₃ photocatalysts for water splitting", Proc. SPIE PC12200, Low-Dimensional Materials and Devices 2022, PC122000A (3 October 2022); https://doi.org/10.1117/12.2636984

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