Synergistic effect of Ag/CuO composites on g-C3N4 nanosheets towards the visible-light active photocatalytic degradation of substituted benzoic acids in novel Ag/CuO@gCN heterojunction composites

Abstract

Advanced oxidation processes (AOPs) with heterojunction-based composites have been shown to be effective for a variety of water and/or wastewater treatments. In this study, a highly efficient visible-light-driven photocatalytic composite composed of Ag/CuO@gCN ternary heterojunction based composites was successfully designed and fabricated via a facile calcination route. The uniformly assembled composites, Ag/CuO on gCN sheets were confirmed using UV–vis DRS, XRD, TEM, BET surface area, and FTIR analysis. A 15 mg/L Ag/CuO@gCN photocatalyst showed the highest photocatalytic degradation of 4-hydroxybenzoic acid (4-HBA, 95.2%) and 3-phenoxybenzoic acid (3-PBA, 81.62%) in 24 min of the reaction. The Ag/CuO@gCN composite for 4-HBA and 3-PBA degradation were obtained at a maximum degradation rate of 2.64 × 10−1 s−1 and 2.11 × 10−1 s−1, respectively and follows pseudo-first-order reactions. The photocatalytic activities for degradation of 4-HBA and 3-PBA over Ag/CuO@gCN composites are distinctly enhanced, which is higher than that of gCN and Ag/CuO composite due to lamellar configuration of gCN nanosheets and heterojunction between Ag and CuO. Furthermore, a trapping experiment was conducted to estimate the main reactive species in the degradation of 4-HBA and 3-PBA for Ag/CuO@gCN composite stability. The as-proposed Ag/CuO@gCN heterojunction composites may shed light on the design and application of materials in water purification.