Enhanced photocatalytic hydrogen generation from barium tantalate composites

Abstract

(111)-layered Ba₅Ta₄O₁₅ photocatalysts were synthesised by a solid state reaction route and a citrate synthesis route, and their structural and electronic properties were investigated. After citrate route preparation, the presence of a second phase, namely Ba₃Ta₅O₁₅, was determined by X-ray powder diffraction and absorption spectroscopy. The existence of this phase had a profound effect on the photocatalytic activity of this Ba₅Ta₄O₁₅/Ba₃Ta₅O₁₅ composite in comparison to the pure Ba₅Ta₄O₁₅ materials. The photocatalytic performance of the barium tantalates was evaluated by investigating the capability in ˙OH radical formation and hydrogen generation. Strongly increased hydrogen evolution rates for the Ba₅Ta₄O₁₅/Ba₃Ta₅O₁₅ composite, up to 160% higher than for the pure Ba₅Ta₄O₁₅, were determined, and only very small amounts of Rh co-catalyst, deposited on the photocatalysts by stepwise reductive photo-deposition, were needed to achieve these results.