A Multi-step Synergistic Strategy for Upgrading Plastic Waste into Circular Economy Feedstocks

A significant amount of abandoned plastics has caused serious harm to the environment and ecosystems. The urgent demand for carbon-neutral technology has driven the effective recycling of plastic waste. Various chemical approaches have been extensively explored for plastic waste management, with recycling strategies aimed at selectively producing high-value products garnering increasing attention. Notwithstanding considerable progress, each treatment method possesses certain constraints. Multi-step cascade coupling offers a viable strategy for efficient plastic recycling, affording enhanced selectivity towards desired products. This review provides a systematic review of the reaction mechanisms and representative studies of pyrolysis, photocatalysis and electrocatalysis for various types of plastics. A strategy centred on the design of specific intermediate molecules enables a polymer conversion pathway where depolymerisation into monomers, oligomers or other intermediates is followed by their selective transformation into high-value chemicals. Uniting established methods like thermal degradation and solvolysis with emerging fields-including photocatalysis, electrocatalysis and biotransformation-this review proposes a coherent framework for the rational design of multi-stage or cascade plastic recycling processes. This approach paves the way for the efficient transformation of abandoned plastics into valuable chemicals.