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Co-Electrolysis of PET and CO2 using a Co-MOF-74-Derived Anode and a Polymeric Co-Phthalocyanine Cathode

Ecotoxicology 2025
Raúl Rojas‐Luna, Lewis S. Cousins, Rhiannon Germaney, Dolores G. Gil‐Gavilán, Miguel Castillo‐Rodríguez, Daniel Osorio, Thomas Doughty, Dolores Esquivel, Charles E. Creissen, Souvik Roy

Summary

This study presents an electrochemical approach that simultaneously breaks down PET plastic waste and converts CO2 into useful products using a cobalt-MOF-74-derived anode. The co-electrolysis system couples plastic oxidation with carbon dioxide reduction, offering a dual-benefit strategy for waste valorization and greenhouse gas utilization. Results demonstrate the feasibility of integrating plastic recycling with carbon capture in a single electrochemical cell.

Polymers

Mitigating carbon emissions and plastic waste is a pressing societal challenge due to the disruptive environmental impact of incremental accumulation. A promising strategy to address both issues involves the development of coupled electrolysers that can utilise CO2 and PET-plastic waste as resources for electricity-driven manufacturing of high-value commodity chemicals. Here, we report electrocatalytic upcycling of polyethylene terephthalate (PET) plastic to formate and terephthalic acid using a cobalt-based metal-organic framework (Co-MOF-74). The electrocatalyst undergoes oxidative restructuring to cobalt oxyhydroxide (CoOOH) under operating conditions which is demonstrated using ex situ and in situ measurements. The MOF-derived electrocatalyst exhibited near-unity faradaic efficiency (FE) for oxidation of ethylene glycol to formate during short-term electrolysis and lowered the required potential by 0.23 V compared to the conventional oxygen evolution reaction (OER) at a current density of 100 mA cm–2. When coupled with a CO2R electrode containing a polymeric cobalt-phthalocyanine catalyst in a two-electrode configuration, a maximum combined FE of 156% was achieved for formate (anode) and syngas (cathode) at a cell voltage of 1.6 V. Upon integration of the EGOR electrode in a CO2-fed flow cell, the coupled system required a cell voltage of ~2.3 V to operate at 75 mA cm−2 current density. This work presents a promising integrated approach that offers a compelling solution for mitigating environmental pollution by enabling the electrochemical reforming of CO2 and plastic waste into valuable chemicals under cost-effective and energy-efficient conditions.

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