Origin of the overall water splitting activity over Rh/Cr2O3@ anatase TiO2 following UV-pretreatment

Anatase TiO2 has long been known to be one of the best photocatalysts. Its conduction band potential is thermodynamically allowed to drive a diverse range of photooxidation reactions. However, anatase TiO2 cannot oxidize water into oxygen in photocatalytic overall water splitting that involves multi-hole transfers. In the present study, a simple pretreatment of anatase TiO2 with highly-intense UV irradiation is demonstrated to enable overall water splitting upon loading with a Rh/Cr2O3 cocatalyst. Based on light-induced infrared absorption spectroscopy and time-resolved microwave conductivity, it is suggested that the efficient removal of deep hole traps permits free holes to possess a sufficiently strong oxidizing potential for water oxidation over Rh/Cr2O3@TiO2.