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

## TL;DR

A new catalyst efficiently breaks down plastic waste into useful chemicals while generating hydrogen, using a unique sulfur-stabilized material.

## Contribution

A sulfur-stabilized high-entropy oxysulfide catalyst is developed for efficient ethylene glycol electrooxidation with high formate selectivity.

## Key findings

- The catalyst achieves 84.6% faradaic efficiency for formic acid production.
- Sulfur incorporation stabilizes oxygen vacancies and enhances electronic structure for better performance.
- Replacing oxygen evolution with ethylene glycol oxidation reduces cell voltage significantly.

## Abstract

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.

Room‐temperature synthesis method of high‐entropy oxy‐sulfide (HEOS) is introduced. Compared to high‐entropy oxides (HEO), sulfur incorporation promotes oxygen vacancy stabilization and facilitates C—C bond cleavage, improving efficiency of ethylene glycol electrooxidation to formic acid. Lower cell overall voltage enables sustainable plastic upcycling and green hydrogen generation, showcasing catalytic performance through tailored defect engineering and electronic modulation over HEO.© 2026 WILEY‐VCH GmbH