Single-Atom Fe-N4 on a Carbon Substrate for Nitrogen Reduction Reaction

Ammonia plays an important role in production and life, but the high energy consumption of the industrial Haber-Bosch process encourages people to study nitrogenase, which can convert nitrogen into ammonia under environmental conditions. Here, we reported an atomically dispersed Fe-N-4 fixed on a carbon substrate (Fe-N/C) with the Fe single atom loading up to 3.5 wt % and the specific surface area reaching up to 1088.96 m(2) g(-1). Furthermore, Fe-N/C was modified on carbon papers (CPs) to form Fe-N/C-CPs as effective electrochemical nitrogen reduction reaction (NRR) catalysts, achieving an R-NH3 of 2.27 mu g h(-1) mg(-1) with an FE of 7.67% at -0.2 V (vs RHE). The uniformly dispersed and high ratio Fe single atoms in Fe-N/C ensure that the active sites can be fully exposed, which has the ability to reduce the stable N N triple bond and facilitate subsequent activation and hydrogenation of nitrogen molecules, improving the electrocatalytic NRR activity. Density functional theory theoretical calculations proved that Fe-N/C-CPs with the Fe-N-4 configuration, which catalyzes the reduction of nitrogen by the alternating mechanism, can effectively reduce the Gibbs free energy in the rate-determining step, thereby increasing the catalytic activity.