Electrocatalytic upcycling of polyethylene terephthalate to commodity chemicals and H ₂ fuel

Abstract

Plastic wastes represent a largely untapped resource for manufacturing chemicals and fuels, particularly considering their environmental and biological threats. Here we report electrocatalytic upcycling of polyethylene terephthalate (PET) plastic to valuable commodity chemicals (potassium diformate and terephthalic acid) and H ₂ fuel. Preliminary techno-economic analysis suggests the profitability of this process when the ethylene glycol (EG) component of PET is selectively electrooxidized to formate (>80% selectivity) at high current density (>100 mA cm ⁻²). A nickel-modified cobalt phosphide (CoNi _0.25P) electrocatalyst is developed to achieve a current density of 500 mA cm ⁻² at 1.8 V in a membrane-electrode assembly reactor with >80% of Faradaic efficiency and selectivity to formate. Detailed characterizations reveal the in-situ evolution of CoNi _0.25P catalyst into a low-crystalline metal oxy(hydroxide) as an active state during EG oxidation, which might be responsible for its advantageous performances. This work demonstrates a sustainable way to implement waste PET upcycling to value-added products.

Abstract

Plastic upcycling to value-added products is of great interests. Here the authors investigate a nickel-cobalt phosphide electrocatalyst for electroreforming of polyethylene terephthalate plastic toward valuable potassium diformate, terephthalic acid, and H ₂ fuel.