Effect of activated carbon on the photocatalytic activity of CuInS2 in aqueous solution under visible light irradiation

In this study, CuInS 2 (CIS) was prepared using the liquid phase reflux method, and different amounts of activated carbon (AC) are loaded onto CIS via a wet grinding method to prepare AC/CIS composites with varying composite ratios. The crystal structure, surface elemental composition, oxidation states, morphology, specific surface area, and optical properties of CIS and AC/CIS were analyzed ussing techniques such as X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), Brunauer–Emmett–Teller (BET) analysis, photoluminescence (PL), and ultraviolet–visible diffuse reflectance spectroscopy (UV–Vis-DRS). Rhodamine B (RhB) was used as a model pollutant to investigate the visible-light photocatalytic activity of CIS and AC/CIS. The optimal mass load ratio for AC was determined to be 3%. At this optimal ratio, AC/CIS demonstrated the capability to degrade 80% of RhB within a span of 2 h. The judicious incorporation of AC enhances the visible light absorption of CIS, accelerates electron migration, which facilitates the separation of photogenerated carriers, thereby increasing the visible-light photocatalytic activity and recyclability stability of CIS. Additionally, due to the electrophilicity of AC, the introduction of AC led to a transformation in the main active species during the photocatalytic process, changing from holes (h + ) and hydroxyl radicals (·OH) to superoxide radicals (·O 2 − ). These findings strongly suggest that AC/CIS holds great promise as a visible photocatalyst for effectively degrading pollutants in the environment.