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 H 2 generation. Here, we synthesis of MoS 2 -graphene composite as a highly-efficient cocatalyst to enhance the photocatalytic activity of ZnIn 2 S 4 under visible light irradiation. Through the optimizing of each composition proportion, the hierarchical MoS 2 -graphene/ZnIn 2 S 4 photocatalyst shows the highest H 2 evolution rate of 4169 μmol h −1  g −1 under visible light irradiation in presence of Na 2 S and Na 2 SO 3 as sacrificial reagents when the content of MoS 2 -graphene is 1.2 wt% and the weight ratio of MoS 2 to graphene is 10:1, which is almost 22.8 times higher than that of pure ZnIn 2 S 4 . More importantly, the ternary MoS 2 -graphene/ZnIn 2 S 4 composite exhibits much higher photocatalytic activity than Pt-loaded ZnIn 2 S 4 photocatalyst, suggesting that the MoS 2 -graphene composite can act as a more efficient cocatalyst than the commonly used Pt metal. The superior catalytic activity of MoS 2 -graphene cocatalyst can be assigned to the positive synergistic effect between MoS 2 and graphene, which act as a hydrogen evolution reaction catalyst and an electron transport bridge, respectively. The effective charge transfer from ZnIn 2 S 4 to MoS 2 through graphene is demonstrated by the significant enhancement of photocurrent responses in MoS 2 -graphene/ZnIn 2 S 4 composite photoelectrodes.