Incorporating Ordered Indium Sites into Rhodium for Ultra-Low Potential Electrocatalytic Conversion of Ethylene Glycol to Glycolic Acid.

Abstract

The upcycling of polyethylene terephthalate (PET)-derived ethylene glycol (EG) to glycolic acid (GA, a biodegradable polymer monomer) via electrocatalysis not only produces valuable chemicals but also mitigates plastic pollution. However, the current reports for electrooxidation of EG-to-GA usually operate at reaction potentials of >1.0 V vs reversible hydrogen electrode (RHE), much higher than the theoretical potential (0.065 V vs RHE), resulting in substantial energy wastage. Herein, body-centered cubic RhIn intermetallic compounds (IMCs) anchored on carbon support (denoted as RhIn/C) are synthesized, which shows excellent performance for the EG-to-GA with an onset potential of only 0.35 V vs RHE, lower than the values reported in current literature. The catalyst also possesses satisfactory GA selectivity (85% at 0.65 V vs RHE). Experimental results combined with density functional theory calculations demonstrate that RhIn IMCs enhance the adsorption of EG and OH^-, facilitating the generation of reactive oxygen species and thereby improving catalytic performance. RhIn/C also exhibits excellent electrocatalytic performance for hydrogen evolution reaction, ensuring that it can be used as a bifunctional catalyst in the two-electrode system for EG electrooxidation coupled with hydrogen production. This work opens new avenues for reducing the energy consumption of electrocatalytic upcycling of PET-derived EG and clean energy production.