Synthesizing a Ternary TiO ₂ @g‐C ₃ N ₄ /UiO‐66 Photocatalyst From Waste Polyethylene Terephthalate Plastic to Treat Polystyrene Microplastics in Polluted Water

A ternary TiO ₂ @g‐C ₃ N ₄ /UiO‐66 photocatalyst was synthesized using terephthalic acid recovered from waste polyethylene terephthalate bottles, providing a green strategy for both plastic upcycling and microplastics (MPs) degradation (TiO ₂ = titanium dioxide; g‐C ₃ N ₄ = graphitic carbon nitride). Comprehensive characterizations confirmed the successful integration of TiO ₂ , g‐C ₃ N ₄ , and UiO‐66 into a stable heterojunction with enhanced visible‐light response and efficient charge transfer. Under visible‐light irradiation, the composite achieved up to 90% degradation of polystyrene (PS) MPs within 30 h. Electrochemical impedance spectroscopy revealed its lowest charge–transfer resistance, correlating with superior separation of photogenerated carriers and strong reactive oxygen species (ROS) ( ^• O ₂ ^‐ , ^• OH) generation. These ROS actively fragmented PS chains into smaller oxidized intermediates, confirming the material's excellent photocatalytic potential for MPs removal and environmental purification.