Engineering the Local Electronic Configuration of Diatomic Iron-Nickel Site for Enhanced Nitrate and Ammonia Co-Electrolysis Activity

Anthropogenic activities have caused a significant rise in nitrate and ammonia nitrogen levels in natural water bodies, disrupting the balance of the nitrogen cycle. The electrocatalytic reduction of nitrate and the oxidation of ammonia are promising strategies for converting polyvalent nitrogen into nontoxic and harmless N₂. Herein, a bifunctional electrode loaded with diatomic iron-nickel site on porous N-doped carbon (FeNi-NC) is designed and successfully applied for the co-electrolysis of nitrate and ammonia. The incorporation of the Fe atom shifts the partial density of states of Ni 3d away from the Fermi level and suppresses the 3d-2π* coupling between Ni sites and superficial N₂, leading to the easy desorption of N₂ intermediates. Consequently, the Faradaic efficiencies of FeNi-NC for N₂ production at the cathode and anode are 90.3% and 99.4% at 1.8 V, respectively, and an electricity consumption saving of 19.4% is achieved. This work provides a feasible strategy to regulate the electronic configuration of atomically dispersed catalysts for sewage treatment.