Directional electron transfer in ZnIn₂S₄/Mo₂TiC₂-Ru for efficient photocatalytic hydrogen evolution

The photocatalytic hydrogen evolution (PHE) rate on ZnIn₂S₄ is severely limited by the low utilization of photogenerated electrons and the sluggish reaction kinetics. Driving the directional transfer of photogenerated electrons to the target site is crucial for enhancing the electron utilization efficiency and the PHE performance. Herein, this study rationally designed a ternary composite photocatalyst ZnIn₂S₄/Mo₂TiC₂-Ru_C, in which Mo₂TiC₂-Ru_C serves as an electron acceptor and efficient active site. The in-situ KPFM and Mott-Schottky results indicate that the establishment of interfacial electron transport channel accelerates the transfer of photogenerated electrons from ZnIn₂S₄ to Mo₂TiC₂. Density functional theory (DFT) calculations verify the strong metal-support interaction (EMSI) and interfacial electron delocalization of Mo₂TiC₂-Ru_C, which synergistically optimize the water dissociation at Ru nanocluster and the hydrogen evolution desorption at the Mo₂TiC₂ terminal, promoting the efficient utilization of photogenerated electrons. Therefore, ZnIn₂S₄/Mo₂TiC₂-Ru_C achieved a PHE rate of 6.15 mmol·g^-1·h^-1 under visible light, and demonstrated excellent potential for PHE application under natural light. This study provides a new paradigm for integrating electron transfer dynamics with active site engineering to improve the utilization efficiency of photogenerated electrons in the photocatalytic hydrogen evolution process.