Step-by-step strategy of electron utilization by binary cocatalysts: Coupling electron-reservoir MoS2 with proton-reduction cobaloxime for enhanced photocatalytic hydrogen evolution

Photocatalytic hydrogen production offers a potential route for transforming solar energy into energy. A key challenge lies in developing efficient, noble-metal-free cocatalysts that can simultaneously promote charge separation and catalysis reactions. Inspired by concept of “capacitance catalysis” and the high activity of molecular catalysts for proton reduction, herein, we construct a novel composite photocatalyst by integrating a capacitive MoS 2 cocatalyst and a cobaloxime molecular catalyst onto ZnIn 2 S 4 nanosheets. In the process, MoS 2 operates as an electron reservoir to separate and store photogenerated electrons from ZnIn 2 S 4 , effectively suppressing charge recombination. Meanwhile, the Co Ⅲ molecular catalyst provides abundant active sites for proton reduction. The optimal Co Ⅲ /MoS 2 /ZnIn 2 S 4 composite achieves an exceptional activity rate of 3685 μmol·h −1 ·g −1 , which is 9.2, 4.5, and 1.9 times that of ZnIn 2 S 4 , Co Ⅲ /ZnIn 2 S 4 , and MoS 2 /ZnIn 2 S 4 , respectively. Photoelectrochemical characterizations confirms the synergistic interplay between the two cocatalysts: the larger capacitance of MoS 2 facilitates electron storage and separation, while the Co Ⅲ molecular catalyst accelerates the release and utilization of these electrons for hydrogen production. This work demonstrates a step-by-step strategy of store and then catalysis operated by dual functionally complementary cocatalysts for designing high-performance, non-precious metal photocatalytic systems.