Coupling Polyethylene Terephthalate Plastic Upcycling and Hydrogen Evolution Using Cerium-Doped Nickel Cobalt Sulfide...

Polyethylene terephthalate (PET) is one of the most widely used plastics, whose extensive consumption and limited recyclability have led to severe environmental challenges. Electrocatalytic upcycling of PET has emerged as a promising strategy that not only mitigates plastic waste but also enables the concurrent generation of value-added chemicals and hydrogen (H₂). Herein, cerium-incorporated nickel cobalt sulfide (Ce-NiCoS) catalysts was prepared via one-step chemical bath deposition and utilized for electro-oxidation of real PET-waste derived ethylene glycol (EG) and cathodic hydrogen evolution at industrial-scale current densities. With optimized electronic structure and hierarchical morphology, Ce-NiCoS catalysts demonstrated EG oxidation reaction (EGOR) at 1.30 V vs RHE (reversible hydrogen electrode) at a current density of 100 mA cm^-2, which is lowered by 230 mV, compared to the oxygen evolution reaction. In-situ Raman spectroscopy and electrochemical impedance spectroscopy further confirms the accelerated electro-oxidation of catalysts surface and formation of metal oxyhydroxides sites, which are highly active for the chemical oxidation of EG into formate. Quantitative analysis suggests that the Ce-NiCoS catalysts exhibit a Faradaic efficiency of 99% for H₂-production and 96.5% for EG to FA conversion. Because of thermodynamically favorable EGOR kinetics, PET hydrolysate electrolysis generates 1 N m³ of H₂ utilizing the electrical energy of 4.39 kWh Nm^-3 which is 13% less than the electric input required for fresh water electrolysis (5.05 kWh Nm^-3) and demonstrates the exceptional stability for catalytic performance at industrial scale current density for 60 h. Overall, this integrated approach thus presents a sustainable paradigm for addressing plastic pollution while contributing to carbon-neutral hydrogen production and advancing green chemical technologies.