Synergy between multi-components and Ir dopant in Ir-doped high-entropy alloy nanoparticles for efficient and robust ethylene glycol electro-oxidation at an industrial-level current

Abstract

Electrochemical oxidation of crude ethylene glycol (EG) to commodity chemicals and H₂, powered by renewables energy, is a sustainable and promising strategy for upcycling the end-of-life polyethylene terephthalate (PET) wastes. Pt/Pd group noble metals are deemed as state-of-the-art catalysts for the EG electro-oxidation reaction (EGOR). However, these catalysts suffer from high affinity of the carbonyl intermediates, which consequently results in poisoning of active sites and poor electrochemical stability. Herein, we designed and synthesized small-sized PdPtAuNiCu and Ir-doped PdPtAuNiCu high-entropy alloy nanoparticles (abbreviated as PdPtAuNiCu and Ir-PdPtAuNiCu HEANs, respectively) via a wet chemical method. Benefiting from the multisite synergy and Ir dopant, the as-synthesized Ir-PdPtAuNiCu HEANs achieved selective and robust EGOR to glycolate (GA) in alkaline medium with a high mass activity of 2.41 A mg⁻¹ at 0.724 V versus reversible hydrogen electrode (vs. RHE) and a glycolate Faradaic efficiency (FE_GA) of 88.8%. In a home-made membrane-free flow electrolyzer assembled with this bifunctional catalyst [(−)PdPtAuNiCu∥Ir-PdPtAuNiCu(+)], ultra-stable EGOR was realized beyond 1200 h at an industrial-level current density of >300 mA cm⁻² under a low voltage of 0.724 V. These findings provide a new paradigm for designing efficient and robust EGOR catalysts that can supersede other electrocatalysts for practical applications.