Dynamic Material Reconstruction Dominates Stable and Efficient Upgrading of Polyester Plastics in Electrolyzer Stacks With High Voltage Fluctuations.

Abstract

The electrooxidation of ethylene glycol (EG) from polyethylene terephthalate (PET) waste to produce valuable commodities offers a novel approach to the circular plastic economy. However, reaction efficiency is significantly limited by uncontrollable side reactions and competitive water oxidation, particularly at high or fluctuating voltages. Here, we present an efficient EG-to-formate evolution at an ultrawide potential range of 1.4-2.3 V versus reversible hydrogen electrode, with Faradaic efficiencies of over 95% persisting on a sulfur-modified NiCo-based catalyst. It has been revealed that structural reconstruction engineering, governed by sulfur redox electrochemistry, provides active (oxy)hydroxide sites that promote key C-C scission with good robustness. Accordingly, this system exhibits exceptional durability of over 1100 h in a membrane electrode assembly (MEA) electrolyzer and good tolerance to voltage intermittences and fluctuations. Deployment on a larger scale through a 5 × 4 cm² MEA series stack affords a formate productivity of 193.1 mmol h^-1 at 4.0 A from real-world PET waste hydrolysate, together with high carbon selectivity of 97% and stable operation for 500 h. This electrified process demonstrates great profitability and a negative carbon budget, highlighting its significant potential to advance the circular plastic economy and achieve carbon neutrality.