Metal-Node Engineering Enables Tunable Photocatalytic Benzylamine Oxidation Coupled with H2 Production in MOFs

The precise modulation of the electronic structure in bimetallic metal–organic frameworks (BMOFs), achieved by altering their metal nodes, critically governs their photocatalytic performance. However, how altering the metal nodes in BMOFs regulates the inherent structure–performance relationship remains unclear. Here, a series of CoM-HHTP with similar crystal structures (M = Ni, Cu, and Fe; HHTP = 2,3,6,7,10,11-hexahydroxytriphenylene) were integrated with CdS nanorods, yielding CdS@CoM-HHTP heterojunctions, which exhibited tunable performance in photocatalytic benzylamine coupling and hydrogen evolution. Among them, CdS@Co0.75Fe0.25-HHTP exhibits the best catalytic performance, with a hydrogen evolution rate of 55.29 mmol g–1 h–1 and a benzylamine conversion rate of 63.76%. The experimental results show that substitution of the second metal (M = Ni, Cu, and Fe) effectively modulates the electronic configuration of Co and significantly regulates the ability of BMOFs to extract photogenerated electrons from CdS, thereby enabling tunable photocatalytic activity. This study substantiates that modulation of the secondary metal node is pivotal for achieving synergistic regulation of both the active-site electronic structure and the photocatalytic performance.