Electrochemical CO ₂ Reduction in the Presence of SO ₂ Impurities on a Nitrogen-Doped Carbon Electrocatalyst

High Resolution Image Download MS PowerPoint Slide Electrochemical CO 2 reduction to CO offers a sustainable route for converting CO 2 into value-added chemicals and fuels. However, CO 2 streams derived from industrial sources often contain SO 2 impurities that severely poison conventional metal-based catalysts. Here, we report a nitrogen-doped carbon catalyst that exhibits pronounced tolerance and stability for CO 2 -to-CO conversion in the presence of SO 2 (100–10,000 ppm). The catalyst maintains over 90% Faradaic efficiency toward CO during 8 h of electrolysis at −1.0 V vs RHE with 100 ppm of SO 2, whereas Ag foil electrodes undergo rapid deactivation. Density functional theory calculations combined with surface analyses indicate that weak SO 2 adsorption and the absence of stable sulfur accumulation on nitrogen-doped carbon strengthen its resistance to impurity-induced deactivation, in contrast to Ag catalysts that form Ag 2 S. Gas-fed tests in a membrane electrode assembly (MEA) electrolyzer further confirm that nitrogen-doped carbon sustains high CO selectivity at elevated current densities, while Ag nanoparticles suffer irreversible sulfur poisoning. These results demonstrate that nitrogen-doped carbon is intrinsically resistant to SO 2 -induced deactivation and highlight its potential as a robust catalyst for CO 2 electroreduction under impurity-containing conditions.