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

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.