Influence of thermal treatment atmosphere on photogenerated charge separation of Pt/N–TiO2/SrTiO3 for efficient hydrogen evolution

Abstract

Solar light-responsive platinized N-doped TiO2/SrTiO3 that was thermally treated under H2 atmosphere (H–0.2Pt/N–TiO2/SrTiO3) exhibited high activity for hydrogen evolution under simulated sunlight irradiation. The hydrogen evolution rate of H–0.2Pt/N–TiO2/SrTiO3 was 2740 μmol/h/g, which was approximately 88 times higher than that of N–TiO2/SrTiO3. Results of X-ray photoelectron microscopy demonstrated that the thermal treatment atmosphere was the main factor that contributed to Pt(0) formation, and the proportion of Pt(0) increased in the following order of air < N2 < H2. Moreover, photoluminescence analysis showed that photogenerated charge separation efficiency was positively correlated with the degree of Pt(0) formation, as evidenced by the better photogenerated electron acceptance of Pt(0). The influences of Pt coating amount and photocatalyst concentration on hydrogen evolution efficiency were also investigated. The highest hydrogen evolution efficiency was attained when the Pt coating amount was 0.2 wt% and the photocatalyst concentration was controlled at 2.0 g/L. The stability and reusability experiments for hydrogen evolution and material characterization showed that the H–0.2Pt/N–TiO2/SrTiO3 with high physicochemical stability is a promising candidate material for practical application.