Bromoargentate/g-C3N4 heterojunction by in situ growth: 2-D bromoargentate framework with a transition metal complex linker and cocatalyst for enhanced photocatalytic activity via g-C3N4 hybrid

Abstract

A 2-D bromoargentate hybrid [{Cu(phen)}₂(μ-OH)₂(Ag₃Br₅)]_n (phen = 1,10-phenanthroline) (1) was prepared by the reaction of Cu(NO₃)₂·3H₂O, AgBr, KBr and phen in a C₂H₅OH/DMF mixed solvent under solvothermal conditions. In compound 1, three tetrahedral AgBr₄ units are interconnected into a 1-D [Ag₃Br₅]_n chain by edge-sharing. The [Ag₃Br₅]_n chains were linked by tetranuclear [{Cu(phen)}₂(μ-OH)₂]₂ complex units via Cu–Br bonds to form the layered bromoargentate hybrid [{Cu(phen)}₂(μ-OH)₂(Ag₃Br₅)]_n. The [{Cu(phen)}₂(μ-OH)₂(Ag₃Br₅)]_n layers were successfully loaded on the surface of g-C₃N₄ by in situ growth under the same solvothermal conditions, and a 1/g-C₃N₄ heterojunction was formed. The 1/g-C₃N₄ heterojunction exhibited a stable and reproducible photocurrent response with a photocurrent density of 23.68 μA cm⁻², which is 2.65 and 8.05 times greater than those of parent 1 and g-C₃N₄, respectively. The degradation conversion of crystal violet (CV) reached 98.0% on the photocatalyst of 1/g-C₃N₄ heterojunction after light irradiation for 60 min. The 1/g-C₃N₄ heterojunction exhibited a much higher photocatalytic efficiency than did 1 and g-C₃N₄ for CV degradation, which suggested that the synergistic effect between 1 and g-C₃N₄ in the heterojunction promoted photocatalytic performance. The investigation of the catalytic mechanism showed that all h⁺, ·OH and ·O₂⁻ species are reactive substances in the photodegradation.