Bioinspired Fe₃C@C as Highly Efficient Electrocatalyst for Nitrogen Reduction Reaction under Ambient Conditions

Abstract

Developing highly efficient non-precious-metal catalysts for electrochemical reduction reaction is vital for artificial nitrogen fixation under ambient conditions. Herein, we report a bioinspired Fe₃C@C composite as an efficient electrocatalyst for nitrogen reduction. The composite based on a leaf skeleton successfully replicates the natural vein structure with multichannels. 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 mg_cat) or 12.80 μg/(h cm²) at a low potential of -0.2 V versus reversible hydrogen electrode (vs RHE), which is better than that of recently reported carbon- and iron-based materials, even comparable with that of noble-metal-based catalyst. Experiments with density functional theory calculations reveal that graphene-encapsulated Fe₃C nanoparticles can improve charge transfer due to core-shell interaction, beneficial for inducing active sites for N₂ adsorption and activation and thereby facilitate ammonia synthesis.