Sustainable and green synthesis of sunlight-activated TiO ₂ –rGO films for photocatalytic water purification

The rising demand for clean water and the release of organic micropollutants from human activities threaten aquatic ecosystems and health. Sunlight-driven photocatalysis offers a sustainable and effective method to degrade these persistent pollutants. In this study, we report a sustainable, single-step green synthesis of TiO2–reduced graphene oxide (rGO) nanocomposites via sunlight-assisted reduction of graphene oxide (GO) in the presence of TiO2 nanoparticles (TiO2-NPs). This eco-friendly approach simultaneously reduces GO and immobilizes TiO2 on rGO sheets, forming uniform, well-integrated photocatalytic films. Under natural sunlight irradiation (∼100 mW/cm²), the TiO2–rGO films achieve ∼98% degradation of methylene blue dye within 45 min—substantially outperforming pure TiO2. Detailed characterization using Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and UV–Vis spectrophotometry confirms successful GO reduction, improved optical response, and enhanced interfacial charge transfer. The incorporation of rGO extends light absorption into the visible range and promotes efficient electron–hole separation. This scalable, low-toxicity method offers a robust platform for fabricating sunlight-activated photocatalysts with high durability and efficiency, suitable for advanced water purification technologies.