P-Induced In Situ Construction of ZnCoMOF@CoP-5 S-Scheme Heterojunctions for Enhanced Photocatalytic H2 Evolution.

ABSTRACT

In view of the fact that the exposed catalytic active sites of single-metal MOFs cannot satisfy the efficient progress of the catalytic reaction, here we constructed a star-shaped bimetallic ZnCoMOF by introducing a Zn source by the partial ion exchange method and coprecipitation method. By controlling the quality of sodium hypophosphite, ZnCoMOF was subjected to different degrees of phosphating to optimize the experimental conditions. The introduction of the more electronegative P can attract more H+ to participate in the reduction reaction. The ZnCoMOF@CoP-5 S-scheme heterojunction was constructed in situ by generating CoP on the surface of ZnCoMOF under a PH3 reducing atmosphere, which exhibited excellent H2 evolution performance. This unique heterojunction effectively promotes the separation and transfer of e--h+ pairs, ensuring a strong redox capability. The best hydrogen-evolution performance of ZnCoMOF@CoP-5 under the EY sensitization system reaches 16 958 µmol h-1 g-1, which has significant advantages over the same type of materials and similar photocatalytic hydrogen-evolution work. Finally, the photocatalytic mechanism was demonstrated by an in situ XPS technique. Our work provides important ideas for the research of bimetallic MOFs in the field of photocatalytic hydrogen evolution.