Unlock high-efficiency ZnIn2S4 photocatalysis via designing hierarchical cocatalyst: Synergistic modulation of interfacial charge transfer and hydrogen adsorption

Cocatalyst engineering represents a promising approach for enhancing photocatalytic performance, yet the rational cocatalyst design to collaboratively optimize charge transfer kinetics and reaction thermodynamics remains a critical challenge. Herein, we developed a cocatalyst reconstruction strategy to fabricate a hierarchical cocatalyst of Mo/MoO 2 via controlled reduction of MoO 3 in an Ar/H 2 atmosphere. Comprehensive experimental and theoretical investigations indicate that the antibonding state electrons in metallic Mo transfer to MoO 2 , leading to increased antibonding-orbital occupancy and a weakened Mo-H ads bond in the Mo sites of Mo/MoO 2 cocatalyst. Furthermore, as the structure evolves from MoO 3 to Mo/MoO 2 , the work function decreases, contributing to a reduced energy barrier and thus facilitating efficient interfacial charge transfer between ZnIn 2 S 4 (ZIS) and Mo/MoO 2 . When coupled with ZIS, the resulting ZIS@Mo/MoO 2 photocatalyst performs an exceptional H 2 generation rate of 23.22 mmol·g −1 ·h −1 and a high apparent quantum yield of 15.26 % at 420 nm. This study demonstrates the feasibility of synergistically regulating kinetics and thermodynamics through rational cocatalyst design, offering a new pathway toward high-performance photocatalytic water splitting.