MoS2-graphene/ZnIn2S4 hierarchical microarchitectures with an electron transport bridge between light-harvesting semiconductor and cocatalyst: A highly efficient photocatalyst for solar hydrogen generation

Abstract

Exploiting photocatalysts with characteristics of cost effectiveness, environmental friendliness, visible light response, high reactivity and good durability is a great challenge for solar H2 generation. Here, we synthesis of MoS2-graphene composite as a highly-efficient cocatalyst to enhance the photocatalytic activity of ZnIn2S4 under visible light irradiation. Through the optimizing of each composition proportion, the hierarchical MoS2-graphene/ZnIn2S4 photocatalyst shows the highest H2 evolution rate of 4169μmolh−1g−1 under visible light irradiation in presence of Na2S and Na2SO3 as sacrificial reagents when the content of MoS2-graphene is 1.2wt% and the weight ratio of MoS2 to graphene is 10:1, which is almost 22.8 times higher than that of pure ZnIn2S4. More importantly, the ternary MoS2-graphene/ZnIn2S4 composite exhibits much higher photocatalytic activity than Pt-loaded ZnIn2S4 photocatalyst, suggesting that the MoS2-graphene composite can act as a more efficient cocatalyst than the commonly used Pt metal. The superior catalytic activity of MoS2-graphene cocatalyst can be assigned to the positive synergistic effect between MoS2 and graphene, which act as a hydrogen evolution reaction catalyst and an electron transport bridge, respectively. The effective charge transfer from ZnIn2S4 to MoS2 through graphene is demonstrated by the significant enhancement of photocurrent responses in MoS2-graphene/ZnIn2S4 composite photoelectrodes.