Fig. 3. CO₂ electroreduction performance in the presence of NO₂ and N₂O.

CO₂ electroreduction Faradaic efficiency, excluding hydrogen Faradaic efficiency, vs. time with the introduction of (a) 0.83% NO₂ (yellow) and (b) 0.83% N₂O (blue) on Cu, Ag, and Sn catalysts at a constant current density of 100 mA cm⁻² in 1 M KHCO₃ for 3 h. Gas feeds were 83.3% CO₂ and 16.7% Ar, and 83.3% CO₂ and 15.87% Ar with 0.83% NO₂ or 0.83% N₂O. NO₂ and N₂O were introduced at t = 0.5 h for 0.5 h. Corresponding Faradaic efficiencies are provided in Supplementary Figs. 6 and 7, and Supplementary Tables 7–12. (c) Loss in Faradaic efficiency during CO₂ electroreduction from the introduction of 0.83% NO, 0.83% NO₂, and 0.83% N₂O on Cu, Ag, and Sn catalysts. Corresponding Faradaic efficiencies are provided in Supplementary Table 13. Error bars represent the standard deviation of three independent measurements.