Regulating the Catalytic Performance of a Dual-Atom Iron Species Deposited on Graphitic Carbon Nitride for Electrochemical Nitrogen Reduction

The electrochemical reduction of nitrogen to ammonia under mild conditions is a promising alternative to the energy-intensive Haber-Bosch process that operates at high temperature and high pressure. Gaining an understanding of the catalytic processes and mechanisms is of great importance to a rational design of desirable electrocatalysts. In this work, based on a detailed investigation of the electrocatalytic nitrogen reduction reaction (NRR) pathways for a dual-atom Fe2 species on graphitic carbon nitride (g-C3N4), we have explored a few external means of regulating the catalytic properties of Fe2. The results demonstrate that applying appropriate tensile stress to the g-C3N4 substrate or doping g-C3N4 with electropositive Na atoms can effectively reduce the overpotential of the NRR, both of which originates from the relative destabilization of the N2 adsorbate but via different mechanisms. Here, the former breaks the scaling relations between the *N2 and *HNN adsorption energies via a geometric effect, while the latter comes from a charging effect. The above two means may also improve the reaction selectivity of NRR in competition with the hydrogen evolution reaction (HER). This work may shed new light on designing and improving electrocatalysts toward the nitrogen reduction reaction.