Photocatalytic Upcycling of Polyester Waste to Organonitrogen Compounds

Plastics, derived from fossil hydrocarbons, represent a substantial reservoir of untapped carbon resources. Yet, more than 90% of plastic products are discarded after brief use. Therefore, transforming this abundant waste stream into valuable chemicals presents both an environmental imperative and an opportunity for sustainable carbon utilization. Powered by renewable energy, photocatalytic plastic upcycling has emerged as a promising strategy for converting plastic waste into value-added products under mild conditions. Among various feedstocks, polyester plastics, particularly polylactic acid (PLA) and poly(ethylene terephthalate) (PET), have attracted considerable attention because their hydrolysis-derived monomers are readily upgraded through photocatalysis. Significant advances have enabled the selective conversion of these monomers into valuable oxidation products. More recently, these oxidation pathways have been extended to synthesize organonitrogen and organosulfur compounds using plastic-derived carbon intermediates, broadening both the product scope and the economic value of plastic upcycling. This review summarizes recent advances in the photocatalytic synthesis of value-added organonitrogen products from polyesters. The main objectives are to (i) highlight opportunities for converting waste plastics into valuable products, (ii) elucidate catalytic mechanisms and design principles to guide future reaction development, and (iii) provide insights for the practical implementation of plastic upcycling technologies.