Molten-salt-assisted synthesis of single-atom iron confined N-doped carbon nanosheets for highly efficient industrial-level CO2 electroreduction and Zn-CO2 batteries

The development of convenient and highly efficient synthetic route to fabricate single-atom catalysts anchored on N-doped carbon nanosheets remains a big challenge for CO2 electrochemical reduction (CO2RR). Herein, we develop a one-step molten-salt-assisted synthesis combined with temperature-programmed thermal activation method to fabricate Fe single-atom supported on N-doped carbon nanosheets (FeNC NSs) for CO2RR. In a flow cell, CO partial current density of FeNC NSs-1000 up to 147.9 mA cm-2 at − 0.66 V with a high turnover frequency above 1 × 105 h-1 is achieved. Experimental results reveal that the active site was the center Fe atom coordinated with four N atoms, accelerating the formation of *COOH intermediate and thus accounts for its superior CO2-CO conversion activity. Theoretical calculations further manifest that the pyrrolic N in second coordination sphere reduces the energy barrier of rate-limiting step and promotes the electron transfer capacity. Moreover, the FeNC NSs-1000 is applied as cathode to rechargeable Zn-CO2 battery, exhibiting high CO selectivity and superior stability.