Electrocatalytic CO₂ Upgrading to Biodegradable Plastic by Bromine-Assisted C₂H₄ Oxidation and Polymerization

The electrochemical upgrading of carbon dioxide (CO₂) to long-chain value-added products has remained challenging due to the complex reaction pathways with sluggish carbon-carbon coupling kinetics. Although ethylene (C₂H₄), a major CO₂ electroreduction product, may serve as a potential alternative for the coupling and carbon-chain elongation, the efficient C₂H₄ oxidation under ambient conditions and selective control of the oxidation level still represent two main bottlenecks for realizing long-chain products. Herein, we demonstrate an efficient tandem electrochemical approach for synthesizing polyglycolic acid (PGA) from CO₂ via the bromine-assisted C₂H₄ oxidation, followed by polymerization under mild conditions. This process is enabled by the temperature-mediated electro-oxidation of C₂H₄ to bromoacetate, which overcomes the diffusion limitation imposed by the electrical double layer at room temperature. The resulting bromoacetate with sp²-hybridized carbon preferentially undergoes intermolecular nucleophilic attack, thus driving polymerization to PGA. This work presents a potential approach for converting CO₂ to biodegradable polyesters.