Presentation Information
[2P19]Opposite charge transfer to CoOOH cocatalyst surface in SrTiO3:Rh,Sb photocatalyst for water splitting depending on excitation wavelength observed by soft X-ray absorption spectroscopy
*Kota Enomoto1, Zi Wang1, Ryo Toyoshima1, Masaaki Yoshida2, Kazuhiko Mase3,4, Hiroshi Kondoh1 (1. Keio University, 2. Yamaguchi University, 3. High Energy Accelerator Research Organization (KEK), 4. Graduate University for Advanced Studies, SOKENDAI)
CoOOH is a promising oxygen evolution reaction (OER) cocatalyst, when combined with Rh/Cr2O3 on a SrTiO3-based photocatalyst, shows the highest quantum efficiency under UV-light irradiation. In this study, we extended this cocatalyst pair to UV- and visible-light-absorbing SrTiO3:Rh,Sb, and investigate the effect of the excitation wavelength on the charge transfer. In-situ soft X-ray absorption spectroscopy revealed that CoOOH was oxidized to Co3+ under UV-light irradiation, indicating an effective hole transfer. In contrast, visible-light irradiation led to a complete reduction to Co2+, indicating undesired electron transfer for the OER. Density functional theory calculations and UV-Vis spectroscopy showed that holes generated under visible light tend to be trapped at Rh dopants (Rh 4d orbitals), leading to electron transfer to CoOOH. These results highlight the importance of understanding charge transfer dynamics depending on excitation wavelength.