Enhancing Photocatalytic and Antibacterial Properties Through a Synergistic Approach in ZnS–CuSe Nanocomposites

This study introduces a novel single-step sonochemical synthesis method for producing pure ZnS and CuSe. It offers a comprehensive report on the fabrication of ZnS─CuSe nanocomposites with varying compositions (90, 70, and 50% ZnS combined with 10, 30, and 50% CuSe), denoted as CZ-1, CZ-2, and CZ-3, via a wet-chemical method. Comprehensive characterization was conducted to assess phase purity, structural integrity, composition, detection of free radicals, and optical properties. The results revealed that the average crystallite sizes of ZnS and CuSe were 46.91 and 20.31 nm, respectively. Morphological analysis showed CuSe formed nanoflakes, whereas ZnS appeared as nanoparticles. Optical properties revealed a red shift in absorption spectra and a decrease in band gap with increasing CuSe concentration. Electrons in the CBM (conduction band minimum) can be captured by •O₂ to produce large amounts of •O₂- and •OH radicals, formed via •O₂- →H₂O₂ →•OH. DFT calculations support these findings, offering insights into how CuSe affects the electronic structure of ZnS. Among the materials, CZ-3 showed superior photocatalytic activity, achieving 98% degradation of methylene blue (MB) dye and effective inhibition of B. subtilis and P. aeruginosa under visible light irradiation.