Visible-light-driven H-2 production from heterostructured Zn0.5Cd0.5S-TiO2 photocatalysts modified with reduced graphene oxides

Although, hydrogen is a promising green energy source, current catalysts for hydrogen production cannot use the full range of visible light. In addition, these catalysts suffer from problems such as rapid charge-carrier recombination. Therefore, a simple strategy to synthesize high-performance catalysts for visible-light-driven H-2 production is required. One promising method of increasing catalyst efficiency is the use of a heterojunction structure. Therefore, in this study, Zn0.5Cd0.5S-TiO2 (ZCS-TiO2) heterojunction photocatalysts were prepared via the controlled growth of Zn0.5Cd0.5S using a facile solvothermal method. The ZCS-TiO2 heterojunction photocatalysts showed high hydrogen production performance from water upon exposure to visible light as a result of the increased separation of photogenerated charges. Based on this success, we further modified the surface of the Zn0.5Cd0.5S-TiO2 catalyst with a reduced graphene oxide (RGO) cocatalyst to produce RGO/ZCS-TiO2 composite heterojunction photocatalysts. These ternary composite heterojunction photocatalysts also showed good hydrogen production from water because of the enhanced electron transport endowed by RGO and the matching band structure between Zn0.5Cd0.5S and TiO2. Furthermore, we investigated the effects of different loadings of RGO, as well as the use of physical mixtures, on the catalytic activity; the optimized 0.5%RGO/50%ZCS-TiO2 composite exhibited distinctly greater photocatalytic activity than the 50%ZCS-TiO2 and ZCS catalysts, as well as the 0.5%Pt/50%ZCS-TiO2 catalyst. Thus, our study demonstrates a new approach for obtaining highly efficient ZCS-based photocatalysts.