Electro-upcycling of PET plastic coupled with hydrogen production using the NiCe@NiTe electrocatalyst

Abstract

Microplastic reformation in conjunction with the electrochemical hydrogen evolution has merits for producing value-added chemicals and mitigating environmental pollution. This study presents an approach for producing green hydrogen by electro-oxidizing PET micro-plastics in conjunction with alkaline electrolysis, which produces hydrogen gas at the cathode and a valuable chemical, formic acid, at the anode. In this work, a hierarchically structured NiCe@NiTe heterostructure is deposited on nickel foam via facile hydrothermal and chemical bath deposition techniques for PET plastic up-cycling at industrial scale current densities. Owing to the interface synergistic effect, an abundance of catalytically active sites, and regulated interfacial charge-transfer, the NiCe@NiTe catalyst exhibits superior HER performance with an overpotential of 243 mV to achieve a 100 mA cm⁻² current density. In situ operando Raman spectroscopy and impedance spectroscopy show the accelerated catalytic oxidation and abundance of in situ formed NiOOH sites. It enables the oxidation of ethylene glycol (EG) at 1.38 V vs. RHE at 100 mA cm⁻², lowering the anodic potential by 250 mV as compared to oxygen evolution. With high selectivity, the NiCe@NiTe catalyst facilitates the conversion of EG to formate with a faradaic efficiency (FE) of 96.5%. Additionally, the FE for hydrogen evolution is more than 93%. The NiCe@NiTe catalyst shows exceptional stability in PET hydrolysate electrolysis (∼70 h). Overall, these findings suggest the capability of the NiCe@NiTe catalyst for highly selective and energy-efficient PET upcycling into value-added chemicals and H₂-fuel production at industrial scale current densities.