Selective Plastic Photo Upcycling to Acetic Acid via Coupled Oxidation and CO₂ Reduction Over an S-Scheme g-C₃N₄/Fe₂O₃ Heterojunction

Photo-assisted upcycling of nonbiodegradable plastic waste offers a sustainable route to mitigate plastic pollution, yet remains limited by low efficiency and poor product selectivity. Herein, we report a S-scheme heterojunction photocatalyst composed of sulfur-doped and sulfonic-acid functionalized graphitic carbon nitride coupled with iron oxide (S-g-C₃N₄/Fe₂O₃) for selective plastic upcycling under ambient conditions. The synthesized catalyst converts polyethylene, polystyrene, and polyethylene terephthalate into acetic acid under simulated sunlight, achieving up to 77% polyethylene conversion with a yield rate of 0.42 mmol g⋅cat⁻¹ h⁻¹. Radical trapping experiments identify (Formula presented.) electrons and holes as the key reactive species. Combined Fourier transform infrared spectroscopy (FTIR), UV-Visible (UV-Vis) spectroscopy, nuclear magnetic resonance (NMR) spectroscopy, and as chromatography analyses confirm CO₂ formation by photooxidation of polyethylene followed and subsequent reduction to acetate. Importantly, the photo upcycling of the commercial plastic products further validated the practicality of this approach for sustainable C₂ chemicals production.