Impurity Tolerance of Unsaturated Ni-N-C Active Sites for Practical Electrochemical CO2 Reduction

Demonstrating the potential of the electrochemical carbon dioxide reduction reaction (CO2RR) in industrially relevant conditions is a promising route for achieving net-zero emissions through decarbonization. This requires a catalyst system that displays not only high activity and stability but also the capacity to deliver a consistent performance in the presence of waste stream impurities. To explore these opportunities, we investigate the role that the Ni coordination structure plays on the impurity tolerance of highly active single-atom catalysts (SACs) during CO2RR. The as-synthesized materials are highly active for CO2RR to CO, achieving a current density of 470 mA cm−2 and a CO selectivity of 99% in a CO2 electrolyzer. We demonstrate, through high-temperature pyrolysis, that a higher concentration of “unsaturated” Ni-N4‑x-Cx sites significantly improves the tolerance to NOx, SOx, volatile organic compounds, and SCN− impurities in aqueous electrolyte, paving the way for SACs capable of CO2RR in industrial conditions.