Selective Upcycling of Polystyrene from Real-Life Plastic Wastes by a Bioinspired Flavin–Scandium–Thiourea Catalytic System

The chemical recycling of plastic waste to value-added chemicals, with the advantages of reducing pollution and lower carbon emissions, shows great potential in the circular economy. However, traditional treatment methods have limitations such as high energy consumption, the need for toxic reagents, limited substrate scope, and low efficiency. Here, we present an efficient and sustainable flavin–scandium–thiourea upcycling method employing an easily available, green, and nontoxic flavin as a catalyst. This method enables the conversion of polystyrene with Mw as high as 1,700,000 g/mol and already-used plastics into benzoic acid with yields of up to 68%. Operating under mild conditions with visible light and ambient air, the protocol features a green catalyst, high efficiency, and broad substrate scope for the selective upcycling of PS from real-life plastic waste, aligning with green chemistry principles.