Unique ternary Ni-MOF-74/Ni2P/MoSx composite for efficient photocatalytic hydrogen production: Role of Ni2P for accelerating separation of photogenerated carriers

A reasonable introduction of MOFs-derived Ni2P with high dispersity is a valid way to reduce the recombination rate of photogenerated electron-holes, thus for more effective visible-light-driven water splitting. In this study, Ni-MOF-74/Ni2P precursor was obtained by low-temperature phosphating method. A ternary heterojunction Ni-MOF-74/Ni2P/MoSx with a unique structure is obtained by a solution-based mixing method. The unique structure of Ni-MOF-74/Ni2P provides advantages for MoSx load. The UV-visible diffuse reflectance spectroscopy proves that the introduction of Ni2P improves the utilization of visible light by the composite catalyst 10%-NPMS and promotes more electrons generation, thereby improving photocatalytic hydrogen production activity. It is proved that the introduced Ni2P can accelerate the separation of photogenerated carriers by characterization (PL, EIS, LSV, etc.) analyses. The composite catalyst 10%-NPMS with the best hydrogen production activity was obtained by adjusting the ratio between Ni-MOF-74/Ni2P and MoSx. The photocatalytic hydrogen evolution of the composite catalyst 10%-NPMS (286.16 μmol) is 28.30, 2.78, 3.79 and 2.41 times that of pure Ni-MOF-74, Ni2P, MoSx and binary 10%-Ni-MOF-74/MoSx within 5 h, respectively. And the hybrid 10%-Ni-MOF-74/Ni2P/MoSx exhibits excellent photocatalytic hydrogen evolution performance and good stability. This research will provide a new strategy for synthesizing unique ternary composite materials by using metal organic framework materials as precursors.