Photocatalytic Splitting of Water into Hydrogen and Oxygen on Organic Dye Modified KTa(Zr)O3 Catalyst

Photocatalytic activity of KTaO3 catalyst to water splitting is much improved by organic dye-modification. In particular, cyanocobalamin (Vitamin B12) is the most effective for improving water splitting activity, and the formation rate of H2 and O2 are achieved values of 1912 and 979 μimol gcat“’h”1, respectively, under the light irradiation from Xe lamp (300W). Mechanism of photocatalytic H2O splitting into H2 and O2 on PtOx/KTa(Zr)O3 modified with various dyes were investigated. Photoluminescence (PL) spectra of KTaO3 catalysts suggested that the excitation energy transfers from KTaO3 to Cr-Tetraphenylporphyrin (Cr-TPP) and PtOx co-catalyst. Transient response of photovoltaic potential revealed that the excitation state of KTaO3 was enlarged over 500 μs by dye-modification. Photo-excited electron in KTaO3 transfers to dye, and a long charge separation state was achieved. Thus, it was suggested that the photocatalytic activity was much improved by increasing lifetime of photo-excited charges which can reach to the reaction site effectively.