Isolation of Metalloid Boron Atoms in Intermetallic Carbide Boosts the Catalytic Selectivity for Electrocatalytic N ₂ Fixation

Abstract

The electrochemical N ₂ reduction reaction (eNRR) is considered to be an attractive alternative to overcome the short‐comings of the Haber‐Bosch method, where the electrocatalysts play a vital role in the eNRR efficiency. Herein, isolated single‐B sites with electron deficiency in intermetallic carbide are rationally designed to trigger charge density redistribution, achieving excellent selectivity for eNRR. The B‐rich VC nanocrystals are in situ synthesized on carbon nanofibers (B‐VC/CNFs), and the ordered intermetallic structure of VC can isolate contiguous B atoms into single‐B sites with specific electronic structures. In light of density functional theory calculations, the as‐designed BCV configuration can regulate the adsorption behavior of N ₂ and decrease the energy barrier for the proton–electron coupling and transferring process (*NN → *NNH), endowing the distinguished activity and selectivity, as evidenced by excellent Faradaic efficiency of 46.1% and NH ₃ yield of 0.443 µmol h ^–1 cm ^–2. The operando Raman spectra reveals the formation of NH intermediates on the surfaces of B‐VC/CNFs, further confirming the calculated eNRR pathway. This intermetallic carbide host strategy for generating electron‐deficient single‐B sites offers powerful guidelines for designing advanced eNRR electrocatalysts to achieve effective ammonia production.