CO2 electroreduction to multicarbon products from carbonate capture liquid

Abstract

Alkali hydroxide systems capture CO 2 as carbonate; however, generating a pure CO 2 stream requires significant energy input, typically from thermal cycling to 900°C. What is more, the subsequent valorization of gas-phase CO 2 into products presents additional energy requirements and system complexities, including managing the formation of (bi)carbonate in an electrolyte and separating unreacted CO 2 downstream. Here, we report the direct electrochemical conversion of CO 2 , captured in the form of carbonate, into multicarbon (C 2+ ) products. Using an interposer and a Cu/CoPc-CNTs electrocatalyst, we achieve 47% C 2+ Faradaic efficiency at 300 mA cm −2 and a full cell voltage of 4.1 V. We report 56 wt % of C 2 H 4 and no detectable C 1 gas in the product gas stream: CO, CH 4 , and CO 2 combined total below 0.9 wt % (0.1 vol %). This approach obviates the need for energy to regenerate lost CO 2 , an issue seen in prior CO 2 -to-C 2+ reports.