Binder-free nickel–iron selenide catalyst arrays for coupling hydrogen production with polyethylene terephthalate plastic electro-upcycling

Abstract

The rational design and optimization of electrode structures are crucial for enhancing catalytic performance for water electrolysis and plastic upcycling, addressing environmental concerns while creating economic value. In this work, a hierarchically structured Ni–Fe₃Se₄ catalyst was deposited on nickel foam by a chemical bath deposition method. The Ni–Fe₃Se₄ catalyst exhibits low interfacial resistance and abundance of NiFeOOH active sites, achieving excellent electrocatalytic performance for industrial-level alkaline water electrolysis and electrocatalytic polyethylene terephthalate (PET) upcycling with conversion of ethylene glycol to formate with a faradaic efficiency of 89%. A bi-functional electrolyser using Ni–Fe₃Se₄ demonstrates excellent stability at 300 mA cm⁻² over 42 hours in a 5 M KOH electrolyte. Interestingly, the Ni–Fe₃Se₄ catalyst shows the simultaneous anodic electro-upcycling of PET hydrolysate and cathodic H₂ production at industrial scale current densities for 50 hours, ensuring sustained performance for transforming waste into value-added products such as H₂-gas, formate, and terephthalate.