High-rate and selective conversion of CO2 from aqueous solutions to hydrocarbons

• Published in: Nature communications Vol. 14; no. 1; p. 3176
• Main Authors: Obasanjo, Cornelius A., Gao, Guorui, Crane, Jackson, Golovanova, Viktoria, García de Arquer, F. Pelayo, Dinh, Cao-Thang
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01.06.2023; Nature Publishing Group; Nature Portfolio
• Subjects: 140/131; 140/146; 147/135; 639/301/299/886; 639/4077/4079; 639/638/161; Aqueous solutions; Bicarbonates; Carbon dioxide; Carbon dioxide concentration; Catalysts; Conversion; Copper; Current density; Electricity; Electrochemistry; Electrodes; Energy efficiency; Humanities and Social Sciences; Hydrocarbon fuels; Hydrocarbons; Mass transport; Methane; multidisciplinary; Science; Science (multidisciplinary); Selectivity; Transportation management
• DOI: 10.1038/s41467-023-38963-y
• ISSN: 2041-1723

Electrochemical carbon dioxide (CO 2 ) conversion to hydrocarbon fuels, such as methane (CH 4 ), offers a promising solution for the long-term and large-scale storage of renewable electricity. To enable this technology, CO 2 -to-CH 4 conversion must achieve high selectivity and energy efficiency at high currents. Here, we report an electrochemical conversion system that features proton-bicarbonate-CO 2 mass transport management coupled with an in-situ copper (Cu) activation strategy to achieve high CH 4 selectivity at high currents. We find that open matrix Cu electrodes sustain sufficient local CO 2 concentration by combining both dissolved CO 2 and in-situ generated CO 2 from the bicarbonate. In-situ Cu activation through alternating current operation renders and maintains the catalyst highly selective towards CH 4 . The combination of these strategies leads to CH 4 Faradaic efficiencies of over 70% in a wide current density range (100 – 750 mA cm -2 ) that is stable for at least 12 h at a current density of 500 mA cm -2 . The system also delivers a CH 4 concentration of 23.5% in the gas product stream. Electrochemical CO2 conversion to methane offers a promising solution for the large-scale storage of renewable electricity, yet the catalytic selectivity at high current density still needs to be refined. Here the authors report to use both dissolved CO2 and in-situ generated CO2 from bicarbonate to sustain high local CO2 concentration around Cu electrode and thus achieve selective CO2 conversion to methane.