Sulfur‐Stabilized High Entropy Oxysulfides Enable Efficient CC Bond Cleavage in Ethylene Glycol Electrooxidation for Sustainable Plastic Upcycling to Formate

The conversion of plastic waste into value-added chemicals coupled with energy-efficient H₂ production is a sustainable strategy for addressing environmental and energy challenges, for example, the selective electrooxidation of polyethylene terephthalate (PET)-derived ethylene glycol (EG) to C1 products via CC bond cleavage is important for advancing PET electro-reforming. Herein, a high-entropy transition metal oxysulfide is synthesized through the one-step room-temperature incorporation of S into a high-entropy transition metal oxide and evaluated as a catalyst for EG electrooxidation under alkaline conditions. Covalently bound S stabilizes O vacancies and high-valence transition metal states through defect-induced charge redistribution, enhancing lattice stability and promoting the establishment of an advantageous electronic structure. The developed catalyst is highly active, selective, and durable, achieving efficient CC bond cleavage and formic acid production with a faradaic efficiency of 84.6%. S incorporation enhances both lattice-oxygen and adsorbed-oxygen mechanism pathways for CC bond cleavage and accelerates hydrogen atom transfer, thereby enabling concerted formate formation. Replacing the anodic O₂ evolution reaction with EG electrooxidation markedly reduces the required cell voltage, highlighting the high-entropy oxysulfide's promise as an electrocatalyst for plastic upcycling and energy-efficient green H₂ generation.