Fe3+-enriched Fe-N-C catalysts promote the electrocatalytic reduction of CO2.

Fe-N-C catalysts are excellent catalysts for electrochemical carbon dioxide (CO2) reduction reactions (CO2RR). However, achieving efficient enrichment of Fe3+ sites in Fe-N-C catalysts is still a challenge. Herein, a low-cost Fe-N-C-Fe(III) catalyst with a high Fe3+ content was successfully prepared using a simple solid-phase synthesis method. The results show that a well-defined Fe-NX coordination structure has been successfully formed in the Fe-N-C-Fe(III) catalyst, with the Fe species predominantly present in the +3 oxidation state. Electrocatalytic CO2 reduction tests show that the catalyst's CO faradaic efficiency can reach 87% at -0.7 V (vs. RHE), which is obviously better than the comparison sample (mainly with Fe2+-NX sites). Furthermore, this Fe-N-C-Fe(III) catalyst exhibits superior electrochemical kinetics and lower charge transfer resistance. During a continuous electrolysis test lasting 19 h, it maintained stable catalytic activity and product selectivity throughout, demonstrating excellent long-term catalytic stability. This work provides new ideas and theoretical references for developing low-cost, high-efficiency electrochemical CO2RR catalysts.