Superior Selectivity and Tolerance towards Metal-Ion Impurities of a Fe/N/C Catalyst for CO₂ Reduction

The electrochemical CO₂ reduction reaction (CO₂ RR) in aqueous solution inevitably competes with the hydrogen evolution reaction (HER), which results in a difficult separation of the complex products. In this study, a Fe/N/C catalyst derived from Fe(SCN)₃ (labelled SMFeSCN) revealed a high CO Faradaic efficiency (FE) of 99 % at a moderate overpotential of 0.44 V. CO₂ RR and HER competed with each other for active sites on Fe/N/C. The high FE for CO production originated from the high content of micropores on the catalyst, which could suppress the side reactions by increasing CO₂ uptake. More importantly, excellent tolerance towards metal-ion impurities was demonstrated in Fe/N/C, which was primarily owing to the high specific surface area with scattered active sites. Thus, the Fe/N/C catalyst showed good activity for CO₂ RR without influencing the electrolyte purity, thus raising the possibility of its practical application.