Green Electrochemical Upcycling of PET Waste via Bimetallic Catalyst-Driven Ethylene Glycol Selective Oxidation to Formate

Abstract

The rapid accumulation of plastic waste has created an urgent need for efficient and sustainable upcycling strategies. Herein, we report a Zn and Cu co-doped spinel oxide electrocatalyst (CuO/ZnCuCo2O4) for the selective electrochemical conversion of polyethylene terephthalate (PET) into formate under mild conditions. Dual-metal incorporation modulates the electronic structure of Co3O4 and optimizes the adsorption-desorption behavior of key intermediates during the ethylene glycol oxidation reaction (EGOR). As a result, the catalyst achieves a current density of 10 mA cm-2 at 1.37 V vs RHE, a high formate Faradaic efficiency of 95.54%, and a formate production rate of 0.78 mmol cm-2 h-1, together with excellent operational stability. When applied to hydrolysates derived from real waste PET, the system still delivers a formate yield of 85.6%, demonstrating strong tolerance to impurities and practical applicability. Density functional theory calculations reveal that the synergistic interaction among Zn, Cu, and Co regulates the electronic structure, facilitates EG adsorption, and lowers the energy barrier of key oxidation steps. This work provides a structure-engineering strategy for high-performance spinel electrocatalysts and advances the electrochemical upcycling of plastic waste.