Boosted production of formate via paired electro-reforming of poly (ethylene terephthalate) plastic and CO2 reduction

Abstract

Electrocatalytic upcycling of polyethylene terephthalate (PET)-derived ethylene glycol into high-value formate enables dual environmental and economic benefits. Here, we developed a SnO₂/NF electrode that achieved exceptional formate production via PET upcycling, delivering 99.8% Faraday efficiency and a superior production rate of 3.24 mmol cm⁻² h⁻¹. Mechanistic studies revealed that the ethylene glycol oxidation reaction on SnO₂/NF followed an electrochemical-chemical cascade pathway, NiOOH served as the active site, while SnO₂ functioned as an “electron transfer layer” and a catalytic modulator. The oxygen-affinity sites of SnO₂ effectively suppressed the competing activity of oxygen evolution reaction and concurrently shifted the d-band center of the active Ni center toward the Fermi level. This electronic structure modulation facilitated the adsorption and conversion of aldehyde intermediates, thereby significantly enhancing the selectivity for formate production. In a paired electrolysis system (POR||CO₂RR), the electrode achieved an apparent Faraday efficiency of 182% for formate at a cell voltage of 2.9 V. This study provides novel insights for designing low-cost and high-performance electrocatalysts for the value-added conversion of waste PET plastics.