Reliable hydrogen production from methanol photolysis in aqueous solution by a harmony between In and Zn in bimetallic zinc indium sulfide

Abstract

This study focuses on hydrogen production by methanol photolysis using zinc indium sulfide (ZnxInySz). The X-ray diffraction identified that the synthesized Zn2InS2.5 and ZnInS2.5 particles have a hexagonal Zn3In2S6 structure, but when In of twice amount against Zn is coexisted, the particle exhibits a perfect hexagonal ZnIn2S4 structure. The results in ultra-violet absorption and X-ray photoelectron spectroscopy analysis confirmed that the band-gaps of ZnxInySz particles decrease depend on the coexistence of In. However, the photocurrent which related to the life time of excited electrons was no correlation with the Zn/In molar ratio, and it was the highest on ZnInS2.5 particle with a ratio of Zn:In = 1:1. Eventually, the hydrogen production by methanol photolysis in aqueous solution was the best on ZnInS2.5 particle. This result gives ultimately relevant that the recombination between electrons and holes during methanol photolysis could be suppressed on bimetallic ZnInS2.5 particle.