Synergistic Regulation of Ag Nanoparticles and Reduced Graphene Oxide in Boosting TiO2 Microspheres Photocatalysis for Wastewater Treatment

Dye-contaminated wastewater has become one of the most severe environmental challenges due to the non-biodegradability and toxicity of synthetic dyes. While photocatalytic degradation is considered a green and efficient technology for wastewater purification, conventional TiO₂ suffers from limited light utilization and rapid electron-hole recombination. In this exploration, Ag-TiO₂-RGO nanocomposites were successfully fabricated and systematically investigated by XRD, SEM, TEM, XPS, Raman, and PL spectroscopy. The incorporation of Ag nanoparticles and reduced graphene oxide (RGO) synergistically improved charge separation and transfer efficiency. Photocatalytic activity was evaluated using different dyes as pollutants under visible light irradiation. Among the samples, Ag-TiO₂-RGO-3% exhibited the highest RhB degradation efficiency of 99.5% within 75 min, with a rate constant (K) of 0.05420 min^-1, which was nearly three times higher than that of pure TiO₂. The photocatalyst also showed excellent reusability with only minor efficiency loss after five cycles, and its activity remained stable across a wide pH range. Radical trapping experiments revealed that •O₂^- served as the dominant reactive species, with additional contributions from •OH and photogenerated holes (h⁺). A possible photocatalytic mechanism was proposed, in which Ag nanoparticles and RGO effectively suppressed electron-hole recombination and accelerated the formation of reactive oxygen species for efficient dye mineralization. These findings demonstrate that Ag-TiO₂-RGO-3% is a promising photocatalyst with high activity, stability, and environmental adaptability for wastewater remediation.