Electrocatalytic upcycling of PET-derived ethylene glycol: Mechanism-guided catalyst design for selective glycolate and formate production

Polyethylene terephthalate (PET) is one of the most abundant polyester wastes, and its efficient upcycling remains a major challenge for circular materials management. Chemical upcycling, particularly alkaline hydrolysis, converts PET into terephthalate and ethylene glycol (EG), however, the water-soluble feature of EG complicates its separation from PET hydrolysates. Direct electrooxidation of PET-derived EG therefore provides an attractive route for coupling plastic valorization with cathodic hydrogen evolution. EG oxidation can proceed through C2-preserving pathways toward glycolate or through C-C-cleavage pathways to formate, which could be substantially converted to value-added glycolic acid or potassium diformate. Achieving selective conversion requires simultaneous control of hydroxyl activation, adsorption of oxygenated C2 intermediates, C-C bond retention or cleavage, and catalyst reconstruction under anodic conditions. This review summarizes recent advances in electrocatalytic upcycling of PET-derived EG, with emphasis on the mechanistic origins of glycolate and formate selectivity. Then, we introduce the electrocatalyst engineering strategies as guided by the mechanisms, including interfacial, alloying, strain, reconstruction, defect, and multicomponent (high entropy) engineering strategies in addition to their roles in regulating surface electronic structure, *OH adsorption and intermediates conversion. Finally, we outline opportunities for non-noble-metal catalysts for C2 pathway, dynamic potential pulse control, advanced in-situ characterizations and data-driven discovery of electrocatalysts.