Alkaline induced indium gradient distribution in ZnmIn2S3+m/In(OH)3 heterojunction for improved photocatalytic H2 generation

Abstract

Building a heterojunction composite which contains two or more semiconductors with matching energy band structures is an effective way to boost the photocatalytic performance. In this paper, a perfectly matching heterojunction constructed by semiconductors with a continuously changing energy band structure was demonstrated. It was found that migration of indium in layered ZnIn2S4 could be driven from the bulk to the surface under alkaline condition. Based on this, In(OH)3 was in situ grown on the surface of ZnIn2S4, and meanwhile, ZnIn2S4 was converted to ZnmIn2S3+m with m continuously variable. Due to the concentration gradient of indium, the conduction band (CB) of ZnmIn2S3+m/In(OH)3, which was formed by In5s5p orbitals mixed with Zn4s4p orbitals, displays a continuous change that can efficiently promote photogenerated charge separation and transfer.