In situ decoration of 2D-MoS2/ZIF-67 type II heterojunction for enhanced hydrogen production under simulated sunlight

Selecting narrow band gap semiconductors to design type II heterojunctions is essential, as it optimizes band alignment for efficient charge carrier separation and transfer. In this report, a binary 2D-MoS₂/ZIF-67 composite was prepared using an in-situ growth method for enhanced photocatalytic hydrogen production applications. The controlled loading of the MoS₂/ZIF-67 (MSZ-25) composite demonstrated an impressively high H₂ production rate of 8.13 mmol g⁻¹ h⁻¹, compared to pristine MoS₂ and ZIF-67, due to the synergistic acceleration of the built-in electric field and the effective hindrance of charge recombination. In view of the narrow band gap features of both materials, the as-designed hybrid nanostructured catalysts effectively harness a broad range of the visible light spectrum. Microscopic analysis of the MoS₂ sheets on the ZIF-67 rhombic dodecahedron reveals a type II junction architecture that not only enhances electron transfer capabilities but also ensures well-aligned band positions with ZIF-67, creating a feasible thermodynamic pathway for electron transmission and resulting in increased photocatalytic activity. Further investigation confirms the in-situ formation of Co₃S₄ during photoirradiation with Na₂S/Na₂SO₃ sacrificial scavengers. Additionally, DFT studies revealed the alignment of electronic energy levels and the band gap of the binary 2D-MoS₂/ZIF-67 hybrid, which exhibits semiconducting properties with an indirect band gap of 2.00 eV.