Synthesis and characterization of a highly sunshine active metal sulfide modified TiO2 photocatalyst and its multiple applications

Abstract

The Ag₂S-loaded TiO₂ (Ag₂S–TiO₂) nanocatalyst was effectively synthesized via the precipitation thermal decomposition method. The catalyst was characterized using BET, FT-IR and
HR-TEM studies. The photocatalytic and antioxidant applications of the prepared catalyst were reported. To evaluate its photocatalytic efficiency, the deterioration of Methylene Blue (MB) in an aqueous solution under sunlight exposure was used. Ag₂S–TiO₂ demonstrated greater efficiency than TiO₂, and Ag₂S in the mineralization of MB at pH 7. The impact of various operational parameters, including photocatalyst dosage, dye concentration, and initial pH on MB photomineralization was systematically investigated. Active species trapping experiments revealed that superoxide radical anions, followed by holes and hydroxyl radicals, play a key role in the photocatalytic deterioration of MB. COD measurements confirmed the successful mineralization of MB and the catalyst exhibited excellent reusability. The deterioration process was significantly accelerated by electron acceptors such as H₂O₂ and K₂S₂O₈. The kinetics of heterogeneous photocatalytic deterioration were effectively described using the Langmuir-Hinshelwood (L-H) kinetic model. The synthesized compound was further evaluated for antioxidant activity, and the results indicated that Ag₂S–TiO₂ nanocatalyst was potentially effective antioxidant agent.