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 H2 evolution (9343 μmol g–1 h–1) and O2 reduction (2339 μmol 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.