Fig. 4: CO₂RR performance of the functionalized Ag–Cu electrodes measured in MEA electrolyzers.

a Relationship between the current and cell voltage relationship of pristine, C₃-, C₂N-, N₃N- and N₂SN- functionalized electrodes. The CO₂RR electrolysis was operated using CO₂ with a flow rate of 10 sccm, 0.1 M KHCO₃ anolyte with a flow rate of 30 mL min⁻¹. b Corresponding partial current density for the C₂₊ products. c Comparison of FEs for C₂₊ on the different Ag–Cu electrodes measured at full-cell potentials ranging between −3.5 and −4.8 V. d Evolution of the Faradaic efficiency for C₂₊ and H₂ with the CO₂ flow rate. e Evolution of the FEs and full-cell energy efficiency (EE) for C₂₊ as a function of specific current densities for C₂₊ on the N₂SN- functionalized Ag–Cu electrode. The error bars represent the standard deviation of three independent samples measured under different current densities. f Comparison of the performance metrics of the MEA electrolyzers based on N₂SN-functionalized Ag–Cu cathodes with literature benchmark. For each report, the plotted values are those corresponding to the longest duration test^{32, 65,66,67}. The references are from refs. ³², ⁶⁵, ⁶⁶, and ⁶⁷. g CO₂RR performance of N₂SN-Ag–Cu catalyst at a full-cell potential of −4.55 V and with a 10 sccm feed in CO₂ over 100 h. The anolyte consisted in a 0.1 M KHCO₃ solution with a flow rate of 30 ml min⁻¹. The blue line represents the current recorded during the extended CO₂RR experiment (primary y axis). Each orange, gray, green, and purple spheres represent the FEs for C₂H₄, H₂, CO and C₃H₆ averaged from three independent measurements (secondary y axis). The error bars in a, b, c, and e represent the standard deviation of three independent measurements.