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 mgcat) 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.

Exploration and Investigation of Periodic Elements for Electrocatalytic Nitrogen Reduction

“…It was synthesized by soaking Bodhi leaves in Fe(CH 2 CO 2 ) 2 and followed by annealing at high temperatures. [ 154 ] Interestingly, it displayed an efficiency of 9.15% at 12.80 µg h −1 cm −2 NH 3 yield rate. High performance was attributed to increased active sites and graphene, which shields from corrosion.…”

Atomic Structure Modification for Electrochemical Nitrogen Reduction to Ammonia

“…The core–shell structure has also been applied in electrocatalytic nitrogen fixation currently on account of some structural advantages. First, “shell” acts as a protective layer to protect the core components from corrosion or dissolution when is composed of stable‐state phases . For example, Yang et al modified the gold core with metal‐organic framework (MOF)‐8 shell, which not only wrapped the gold core as a protective layer, but also regulated the diffusion layer near the surface of the gold core to promote the nitrogen fixation reaction .…”

“…For example, Yang et al modified the gold core with metal‐organic framework (MOF)‐8 shell, which not only wrapped the gold core as a protective layer, but also regulated the diffusion layer near the surface of the gold core to promote the nitrogen fixation reaction . Meanwhile, Peng et al found that the carbon layer in Fe 3 C@C heterostructure played a similar role in preventing the Fe 3 C core from being corroded during the catalytic process . Second, supernumerary active sites are introduced at the interface due to the tight bond between “core” and “shell;” meanwhile, the so‐called “synergistic effect” or “strong coupling effect” from the core–shell structure may optimize the NRR activity as a contrast with that of each component .…”

“…The NH 3 yield of Co 3 O 4 @NC could reach 42.58 µg h −1 mg cat −1 , much higher than that of the Co 3 O 4 nanoparticles (11.87 µg h −1 mg cat −1 ) and nitrogen‐doped porous carbon (15.28 µg h −1 mg cat −1 ) under the same conditions (Figure d). When the noble‐metal‐based core–shell structure is constructed, the high catalytic activity of the noble metal can be retained, and the preparation cost is also reduced, thus improving the utilization rate of the precious metal, which is of great significance for the practical application of the precious metal in the NRR and can also be extended to the field of transition metals …”

Ammonia Synthesis via Electrochemical Nitrogen Reduction Reaction on Iron Molybdate under Ambient Conditions

“…In nature, there are three distinguished nitrogenase enzymes with metal‐centered catalytic cofactors of FeMo‐co, FeFe‐co, and VFe‐co, respectively . To mimic the catalytic role of nitrogenase enzymes to achieve the synthesis of NH 3 , a series of potential catalysts containing Fe, Mo, and V elements, including Mo nanofilm, MoS 2 , Mo 2 C, MoO 2 , MoP, MoN, Fe 2 O 3 , FeS x , Fe 3 C, and VN, etc., have been tested for electrochemical NRR under ambient conditions. Recently, both experimental and computational studies showed that a combination of ligand, geometric and synergistic effect of bimetal atoms may facilitate electrochemical NRR .…”