Highly crystalline Na0.5Bi0.5TiO3 of a photocatalyst valence-band-controlled with Bi(iii) for solar water splitting

Abstract

Na_0.5Bi_0.5TiO₃ (BG 3.1 eV) with a valence band formed by Bi(III) was found as a new photocatalyst for solar water splitting. The water splitting activity of highly crystalline Na_0.5Bi_0.5TiO₃ synthesized by a flux method was much higher than that of the samples synthesized by a solid-state reaction. The optimized RhCr₂O_x(0.1 mol%)/Na_0.5Bi_0.5TiO₃/CoOOH(0.02 mol%) gave a 5.1% apparent quantum yield at 350 nm and split water even under simulated sunlight irradiation with a 0.05% solar to hydrogen energy conversion efficiency. We have successfully achieved solar water splitting using a one-step photoexcitation type photocatalyst valence-band-controlled with Bi(III).