Facile visible-light upcycling of diverse waste plastics using a single organocatalyst with minimal loadings

The escalating plastic waste crisis stems from limitations in conventional recycling methods, which are energy-intensive and produce lower-quality materials, leaving a substantial portion unrecycled. Here, we report a versatile organo-photocatalytic upcycling method employing an easily accessible phenothiazine derivative, PTH-3CN, to selectively depolymerize an unprecedented array of commodity polymers—including polyethylene terephthalate (PET), polyethylene (PE), polypropylene (PP), polystyrene (PS), polyvinyl chloride (PVC), polyurethanes (PU), polycarbonates (PC), and other vinyl polymers—into valuable small molecules with minimal catalyst loading (as low as 102 ppm). Operating under mild conditions with visible light and ambient air, this protocol requires no additional acids or metals and adapts effectively to mixed and post-consumer plastic waste. Mechanistic analysis reveals that PTH-3CN serves as a precatalyst, decomposing into active triarylamine species that drive efficient depolymerization likely through a consecutive photoinduced electron transfer mechanism. This approach offers a promising, scalable route for sustainable plastic upcycling with broad applicability.