ZIF-67 derived hierarchical hollow Co3S4@Mo2S3 dodecahedron with an S-scheme surface heterostructure for efficient photocatalytic hydrogen evolution

An S-scheme surface heterojunction between Co3S4 and Mo2S3 was constructed successfully via a stepwise hydrothermal method. A rhombic dodecahedral cobalt-based metal-organic zeolite imidazole framework (ZIF-67) is used as the cobalt source and template to participate in the reaction process. ZIF-67 with a dodecahedral structure is first reshaped into cobalt sulfide with a hollow polyhedral structure via a one-step sulfidation reaction. And then, Mo and S species were introduced on the surface of Co3S4 to fabricate Co3S4@Mo2S3 with a hierarchical core-shell structure and S-scheme heterojunction. In comparison, the H-2 evolution activity of Co3S4@Mo2S3 is about 7 and 3 times higher than those of pure Mo2S3 and Co3S4. Density functional theory (DFT) calculations were used to construct the molecular model of Co3S4 and Mo2S3, and the sample's energy band structure was also analyzed. Based on the analysis of a series of characterization results, a H-2 evolution mechanism of Co3S4@Mo2S3 with a S-scheme surface heterojunction was proposed. The formation of the S-scheme surface heterojunction between Co3S4 and Mo2S3 results in a more developed channel to transfer photogenerated electrons and allows the system to retain a more effective redox potential. Besides, the Mo2S3 nanosheet's criss-cross growth on the Co3S4 surface is beneficial to the improvement of the cycle stability of the Co3S4@Mo2S3 composite. This work uses a ZIF-67 polyhedron as the template to provide a new strategy for preparing a hierarchical S-scheme surface heterojunction photocatalyst based on MOFs.