High Carrier Separation Efficiency in Morphology-Controlled BiOBr/C Schottky Junctions for Photocatalytic Overall Water Splitting

As a graphene-like ternary layered material, BiOBr, has emerged as a promising material for photocatalytic degradation and water treatment; however, its potential application in photocatalytic H2 generation has not been explored clearly. In our study, BiOBr/C Schottky junctions with two stack forms, the parallel and vertical junctions, were prepared controllably via CVD. Their applications in photocatalytic H2 generation and overall water splitting have been investigated systematically. Both the parallel and vertical junctions show a breakthrough in light response and H2 generation under visible light (λ > 420 nm). The high H2 generation rate of the parallel junctions can reach up to 2850 μmol h–1 g–1, which is 18 times more than that of the vertical ones, because of the greatly enhanced efficiency of carrier separation. In particular, the parallel junctions exhibit excellent photocatalytic overall water splitting, with an H2 generation rate of 240 μmol h–1 g–1 and oxygen generation rate of 110 μmol h–1 g–1. The active site of the H2 reduction reaction of the two junctions is determined, and the transfer of photogenerated carriers is monitored by Kelvin probe force microscopy. On this basis, the mechanism of carrier separation of parallel and vertical junctions has been analyzed. This work pushes the series of ternary layered materials of BiOBr toward the applications of photocatalytic H2 generation and overall water splitting.