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

Abstract

In this study, a nonstoichiometric roxbyite (Cu 58 S 32 ) phase with nanoplate (np) and snowflake (sf) morphologies was prepared under solvothermal conditions by varying the sulfur source. The Cu 58 S 32 (CS) was subsequently used as a host matrix as well as a copper source for the in situ construction of Cu-BDC-NH 2 /Cu 58 S 32 (CSM) nanohybrid materials. The regulated growth of Cu-MOF nanoplates over the well-crystalline and radially symmetric hexagonal dendritic structure of Cu 58 S 32 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 μmol g −1 h −1 ) and O 2 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.