Accelerated solar light driven photocatalytic degradation of rhodamine B6g using a multicomponent Co3O4/Ag@ZnO/g-C3N4 composite

This work outlines the design and synthesis of a Co₃O₄/Ag@ZnO/g-C₃N₄ nanosheet composite using a simple hydrothermal method. FESEM-EDX and XPS investigations verified the successful integration of the separate components, and XRD and FTIR data showed that the parent materials’ structural integrity and important functional groups were mostly retained inside the composite. Extended visible light absorption and inhibited charge carrier recombination were found in optical investigations employing UV-DRS and photoluminescence spectroscopy. The composite has a high surface area (83.2 m²/g) and a sufficient pore diameter (5.1 nm), which improves catalytic efficiency. Rhodamine B6g (RhB6g), a less studied model cationic fluorescent dye, was degraded under natural sunlight irradiation in order to evaluate the photocatalytic effectiveness of the produced material. With 40 mg of catalyst, the composite showed exceptional activity, degrading a 30 ppm dye solution at pH 12 up to 98% in 80 minutes. Among the studied materials, the composite photocatalyst showed the highest photocatalytic activity with rate constant of 0.0515 minutes -1 followed by pseudo-first order kinetic module which is attributed to effective heterojunction formation, reduced crystallite size, enhanced surface area and pore volume, extended visible-light absorption, and efficient suppression of photogenerated charge carrier recombination Experiments using radical scavenging revealed that superoxide and hydroxyl radicals are key players in the degradation process. ICP/OES result indicated the limited metal leaching and TOC result showed the partial mineralisation. Furthermore, the composite retained structural integrity and catalytic efficacy after multiple cycles, indicating its potential use in practical wastewater treatment systems.