Single atom Cu-N-C catalysts for the electro-reduction of CO2 to CO assessed by rotating ring-disc electrode

11 figures, 1 table.-- Supplementary information available.The electrochemical CO2 reduction reaction (CO2RR) to controllable chemicals is considered as a promising pathway to store intermittent renewable energy. Herein, a set of catalysts based on copper-nitrogen-doped carbon xerogel (Cu-N-C) are successfully developed varying the copper amount and the nature of the copper precursor, for the efficient CO2RR. The electrocatalytic performance of Cu-N-C materials is assessed by a rotating ring-disc electrode (RRDE), technique still rarely explored for CO2RR. For comparison, products are also characterized by online gas chromatography in a H-cell. The as-synthesized Cu-N-C catalysts are found to be active and highly CO selective at low overpotentials (from −0.6 to −0.8 V vs. RHE) in 0.1 M KHCO3, while H2 from the competitive water reduction appears at larger overpotentials (−0.9 V vs. RHE). The optimum copper acetate-derived catalyst containing Cu-N4 moieties exhibits a CO2-to-CO turnover frequency of 997 h−1 at −0.9 V vs. RHE with a H2/CO ratio of 1.8. These results demonstrate that RRDE configuration can be used as a feasible approach for identifying electrolysis products from CO2RR.Authors acknowledge Grant PID2020-115848RB-C21 “STORELEC” project, and TED2021-129694B-C22 “DEFY-CO2” project funded by MCIN/AEI/10.13039/501100011033. They also acknowledge LMP253_21 project funded by Gobierno de Aragón. Sara Pérez-Rodríguez thanks Grant IJC2019-041874-I funded by the MCIN/AEI/10.13039/501100011033. Ana Cristina Giménez thanks CSIC for her JAE Intro ICU 2021-ICB-04 grant. David Ríos-Ruiz acknowledges the Y2020/EMT-6419 “CEOTRES” project funded by the Comunidad Autonoma de Madrid.Peer reviewe