Electrocatalytic Polyester Waste Upcycling via Lattice Oxygen Redox Activation

Electrocatalytic upcycling of waste polyester plastics into valuable organic acids offers a dual solution for mitigating plastic pollution and promoting sustainable carbon cycling. However, practical implementation remains limited by the scarcity of cost-effective and high-performance electrocatalysts. In this work, we investigate MCo₂O₄ (where M═Mn, Fe, Co, Cu, and Ni) as model catalysts and identify lattice oxygen activity as a critical factor governing the electrochemical upgrading of waste polyethylene terephthalate (PET). NiCo₂O₄ demonstrates the highest oxygen activity, characterized by the greatest density of O 2p ligand holes and the closest proximity of the O 2p band center to the Fermi level. Such unique character facilitates lattice oxygen participation in surface electro-oxidation reactions, leading to exceptional performance of up to 98.3% formate selectivity and 98.9% Faraday efficiency, among the highest values reported for transition metal catalysts in alcohol electro-oxidation. We further demonstrate the direct electrocatalytic upcycling of real waste PET plastics, estimating a $739 profit per ton of recycled PET and confirming its economic viability. These results provide critical insights for refining the design principles of electrocatalytic systems aimed at recycling diverse waste materials and pollutants.