Highly dispersed CuFe-nitrogen active sites electrode for synergistic electrochemical CO2 reduction at low overpotential

The electrochemical conversion of carbon dioxide into value-added chemicals and fuels using renewable energy sources is very promising and attractive in terms of both increasing energy utilization and environmental protection. Here we report a highly dispersed CuFe nitrogen–carbon framework as an efficient catalyst coated on carbon paper to form gas diffusion electrode for electrochemical CO2 reduction. Such a electrode not only surmounts the disadvantage of single Cu or Fe electrode but also exhibits high selectivity, low overpotential and high energy efficiency for CO production. The as-fabricated electrode effectively converts CO2 into CO with a low overpotential of 90 mV and high Faradaic efficiency over 90% at low applied potential range from −0.3 to −0.6 V (maximum 95.5% at −0.4 V, all potentials are converted to the reversible hydrogen electrode) with a high CO current density of 2.1 mA cm−2 at −0.5 V, as well extremely high energy efficiency of 78.3% at −0.4 V. It also exhibits robust stability during long-time electrolysis, with about 95% CO selectivity retained after 20 h electrolysis. The density functional theory computations unravel that the exceptionally high CO2 electrocatalytic performance of the CuFe nitrogen–carbon electrode arises from its favorable local coordination environment and electronic structure giving rise to cooperative metal and pyridine N active sites for electrochemical CO2 reduction to CO.