Construction of a Z-Scheme Ag2S-In2S3 Structure: Towards Enhanced Photocatalytic Inactivation of Bacteria and Degradation of 4-Nitrophenol

Water pollution has created an urgent need for eco-friendly and sustainable technologies to remediate water contaminated with emerging pollutants such as nitrophenols and pathogens. In this study, we developed a Z-scheme photocatalytic system using In2S3 and Ag2S semiconductors to treat water contaminated with 4-nitrophenol and bacterium Escherichia coli. The Ag2S-In2S3 (AI) composite was synthesized using a hydrothermal method. The phase purity and oxidation states of the elements in the catalysts were analysed using X-ray diffraction and X-ray photoelectron spectroscopy. The formation of the composite facilitated the effective separation of charge carriers, as demonstrated by time-resolved fluorescence analysis. Compared to pure Ag2S or In2S3, the AI composite exhibited superior activity in the inactivation of bacteria and achieved nearly complete degradation of 4-NP within 1 h. The mechanism of photocatalysis was elucidated through combined analyses using diffuse reflectance spectroscopy (DRS) and ultraviolet photoelectron spectroscopy (UPS). The band gap was determined by DRS, while the band edges were obtained from UPS. Additionally, radical trapping experiments confirmed that hydroxyl radicals were the primary active species, followed by photogenerated holes and superoxide radicals, responsible for the photodegradation of pollutants.