Electrochemical Upcycling of PET to Value-Added Chemicals via Amorphous–Crystalline Interface Engineering

Abstract

Electrochemical upcycling of polyethylene terephthalate (PET) via oxidation of ethylene glycol (EG), a key depolymerization product, provides a sustainable route to convert plastic waste into value-added chemicals using renewable electricity. However, limited surface wettability and suboptimal intermediate adsorption hinder catalytic activity and selectivity. Herein, we report a hierarchical NiCu layered double hydroxide (NiCu-LDH)/NiCo2O4 heterostructure on nickel foam, featuring well-defined amorphous–crystalline interfaces for efficient EG oxidation. The amorphous NiCu-LDH enhances wettability and electrolyte penetration, while the crystalline NiCo2O4 scaffold ensures excellent conductivity and mechanical stability; their synergy enables rapid electron transfer and structural integrity. Interfacial electronic coupling further optimizes adsorption and activation of EG and OH* intermediates, accelerating reaction kinetics. The catalyst delivers high current densities of 100 and 400 mA cm-2 at 1.353 and 1.445 V versus RHE, achieves ~90% Faradaic efficiency for formate across 1.30–1.70 V, and shows negligible current decay over 120 h. The estimated economic benefit of practical PET upcycling is $210.93 per ton. These results highlight that combining enhanced wettability with interfacial electronic modulation provides an effective strategy for sustainable plastic waste valorization.