A Highly Efficient Metal-Free Electrocatalyst of F-Doped Porous Carbon toward N2 Electroreduction

N-2 electroreduction into NH3 represents an attractive prospect for N-2 utilization. Nevertheless, this process suffers from low Faraday efficiency (FE) and yield rate for NH3. In this work, a highly efficient metal-free catalyst is developed by introducing F atoms into a 3D porous carbon framework (F-doped carbon) toward N-2 electroreduction. At -0.2 V versus reversible hydrogen electrode (RHE), the F-doped carbon achieves the highest FE of 54.8% for NH3, which is 3.0 times as high as that (18.3%) of pristine carbon frameworks. Notably, at -0.3 V versus RHE, the yield rate of F-doped carbon for NH3 reaches 197.7 mu g(NH3) mg(cat.)(-1) h(-1). Such a value is more than one order of magnitude higher than those of other metal-free electrocatalysts under the near-ambient conditions for NH3 product to date. Mechanistic studies reveal that the improved performance in N-2 electroreduction for F-doped carbon originates from the enhanced binding strength of N-2 and the facilitated dissociation of N-2 into *N2H. F bonding to C atom creates a Lewis acid site due to the different electronegativity between the F and C atoms. As such, the repulsive interaction between the Lewis acid site and proton H suppresses the activity of H-2 evolution reaction, thus enhancing the selectivity of N-2 electroreduction into NH3.