Electrochemical Reduction of CO2 Catalyzed by Fe-N-C Materials: A Structure–Selectivity Study

Selective electrochemical reduction of CO2 into energy-dense organic compounds is a promising strategy for using CO2 as a carbon source. Herein, we investigate a series of iron-based catalysts synthesized by pyrolysis of Fe-, N-, and C-containing precursors for the electroreduction of CO2 to CO under aqueous conditions and demonstrate that the selectivity of these materials for CO2 reduction over proton reduction is governed by the ratio of isolated FeN4 sites vs Fe-based nanoparticles. This ratio can be synthetically tuned to generate electrocatalysts producing controlled CO/H2 ratios. It notably allows preparing materials containing only FeN4 sites, which are able to selectively reduce CO2 to CO in aqueous solution with Faradaic yields of over 90% and at low overpotential.