[2Dp01-08] Advancement of experimental techniques for surface analysis using synchrotron radiation and its applications: Synchrotron Radiation Surface Science Division's Session

[2Dp07] In situ soft-X-ray absorption spectroscopy study of selective cobalt oxidation in the cocatalyst-loaded SrTiO₃:Al photocatalyst under UV irradiation

*Zi Wang¹, Ryo Toyoshima¹, Masaaki Yoshida², Kazuhiko Mase³, Hiroshi Kondoh¹ (1. Department of Chemistry, Keio University, 2. Department of Applied Chemistry, Yamagichi University, 3. Institute of Materials Structure Science, High Energy Accelerator Research Organization)

In situ observation for the Rh/Cr2O3-CoOOH-loaded STO:Al photocatalyst with Co L-edge SXAS measurements was performed using total electron yield (TEY) mode and conversion electron yield (CEY) mode. Comparing the results from TEY and CEY mode for Co L edge spectrum, CEY mode measurement enables to obtain artificial-reduction-free SXAS data. Without water vapor exposure, Co cannot accept photoexcited holes from the bulk of photocatalyst, but reduced to Co²⁺ under UV-Vis irradiation by showing intensity of pre-edge region increases. As water vapor was introduced to the surface of CoOOH, UV-Vis irradiation induced selective oxidation of Co in the CoOOH OER site. This provides evidence for hole transfer from the STO:Al to the OER site under photoirradiation.