Electronic regulation via dual-defect synergy for boosting electro-reforming of polyethylene terephthalate waste to value-added formate and hydrogen

Abstract

The critical challenge of low polyethylene terephthalate (PET) recycling rates necessitates efficient upcycling methods. The electrocatalytic ethylene glycol oxidation reaction (EGOR) offers a sustainable route to upgrade PET-derived EG into valuable chemicals using renewable electricity, coupled with green H₂ production. However, EGOR's multi-step oxidation requires high-performance catalysts to accelerate the reaction kinetics. Herein, we propose a dual-defect engineering strategy, constructing V,Co-NiO_xH_y with coexisting vacancies and Co dopants to boost the EGOR performance. This synergistic modulation alters the electronic structure and the local coordination of Ni sites, promoting surface reconstruction to active Ni³⁺–O species and optimizing adsorption of EG/OH⁻. Theoretical analyses confirm that dual defects facilitate O–H bond weakening and lower the energy barrier of the rate-determining step. Consequently, the V,Co-NiO_xH_y catalyst achieves superior EGOR performance with a low onset potential of 1.30 V vs. RHE (reversible hydrogen electrode) and 93.3% faradaic efficiency for formate at 1.50 V vs. RHE. In a flow cell for PET waste electrolysis, it requires only 1.95 V at 500 mA cm⁻² and operates stably for 110 h, simultaneously producing formate and H₂. This work demonstrates dual-defect engineering as a powerful approach to develop highly active catalysts for sustainable PET upcycling via integrated electro-reforming.