Snowflake-like Cu-BDC-NH₂/Cu₅₈S₃₂ Binary Nanohybrid for H₂ Evolution and O₂ Reduction

In this study, a nonstoichiometric roxbyite (Cu58S32) phase with nanoplate (np) and snowflake (sf) morphologies was prepared under solvothermal conditions by varying the sulfur source. The Cu58S32 (CS) was subsequently used as a host matrix as well as a copper source for the in situ construction of Cu-BDC-NH2/Cu58S32 (CSM) nanohybrid materials. The regulated growth of Cu-MOF nanoplates over the well-crystalline and radially symmetric hexagonal dendritic structure of Cu58S32 led to the formation of an n-p heterojunction with a large interfacial contact area. Comprehensive characterizations of the nanohybrids unveiled improved light harvesting properties, large electrochemically active surface areas, and synergistic charge mobilization between the constituent semiconductor materials. The surface-aligned ultrathin Cu-MOF nanosheets contained three distinct types of coordinated metal sites involving Cu(II) dimers with a paddle wheel structure and monomeric Cu(II) with a distorted ligand environment. The optimal CSM(sf) hybrid displayed improved photocatalytic activity toward H-2 evolution (9343 mu mol g(-1) h(-1)) and O-2 reduction (2339 mu mol g(-1) h(-1)) under solar light simulation with reaction rates 14-20 times greater than pure semiconductors. The strong surface hydrophilic character, distinct morphology, and high redox ability of photogenerated electrons through the S-scheme charge transfer mechanism accounted for the improved activity of the nanohybrid materials.