Upcycling CO2 into succinic acid (C4H6O4) by cascading CO2 electroreduction with electrocarboxylation

Abstract

Extending carbon dioxide (CO₂) electrocatalysis to afford energy-rich carbohydrates with long carbon chains is significant but still suffers from unsatisfactory selectivity for products with more than three carbon atoms. Here, using CO₂ as the only carbon feedstock, we present a cascade electrolysis strategy for succinic acid (SA; C₄H₆O₄) synthesis by coupling CO₂ electroreduction with electrocarboxylation of in situ-generated ethylene (C₂H₄). An overall CO₂-to-C₄H₆O₄ conversion was achieved. Our findings illustrate that adsorption of in situ-generated C₂H₄ and the rate-determining step (∗C₂H₄ to ∗C₂H₄COO) occur more easily over FeNi foam. Notably, compared with typical CO₂ reduction products, converting gaseous CO₂ into SA lowers separation costs, enhancing economic viability. Our strategy also significantly reduces carbon emissions (−0.174 kg CO₂ per kg SA), compared with conventional strategies (1.94 for petrochemical and 0.88 for bio-based SA). This system accelerates CO₂ conversion into long-chain carbohydrates, facilitating reintegration of this industrial waste gas into the global economy.