Bio-inspired Fe3C@C as highly Efficient Electrocatalyst for Nitrogen Reduction Reaction under Ambient Conditions.

Developing highly efficient non-precious metal catalysts for electrochemical reduction reaction is vital for artificial nitrogen fixation under ambient conditions. Herein, we report a bio-inspired Fe3C@C composite as an efficient electrocatalyst for nitrogen reduction. The composite based on leaf skeleton successfully replicates the natural vein structure with multi-channels. The Fe3C@C core-shell structure as the real active center contributes to selective electrocatalytic synthesis of ammonia from nitrogen with Faraday efficiency of 9.15% and production rate of 8.53 μg/(h mgcat) or 12.80 μg/(h cm2) at a low potential of -0.2 V versus reversible hydrogen electrode, which is better than recent reported carbon-based and iron-based materials, even comparable with noble-metal-based catalyst. Experiments with density functional theory calculations reveal that graphene encapsulated Fe3C nanoparticles can improve the efficiency of electron transfer from Fe3C core to graphene shell, beneficial for inducing active sites for N2 adsorption and activation and thereby facilitate ammonia synthesis.