CO2 electroreduction to multicarbon products from carbonate capture liquid

Abstract

Alkali hydroxide systems capture CO2 as carbonate; however, generating a pure CO2 stream requires significant energy input, typically from thermal cycling to 900 & DEG;C. What is more, the subse-quent valorization of gas-phase CO2 into products presents addi-tional energy requirements and system complexities, including man-aging the formation of (bi)carbonate in an electrolyte and separating unreacted CO2 downstream. Here, we report the direct electrochemical conversion of CO2, captured in the form of carbon-ate, into multicarbon (C2+) products. Using an interposer and a Cu/ CoPc-CNTs electrocatalyst, we achieve 47% C2+ Faradaic efficiency at 300 mA cm -2 and a full cell voltage of 4.1 V. We report 56 wt % of C2H4 and no detectable C1 gas in the product gas stream: CO, CH4, and CO2 combined total below 0.9 wt % (0.1 vol %). This approach obviates the need for energy to regenerate lost CO2, an issue seen in prior CO2-to-C2+ reports.