Asymmetric bridge structure based on NiFe bimetallic sites for optimizing nitrate reduction reaction

Abstract

Achieving precise control and an accurate understanding of reaction processes that occur on catalysts at the molecular level is still challenging yet crucial to digging out ideal materials for the nitrate reduction reaction (NO₃RR). Considering the representativeness of non-precious metal catalysts and the adjustability of their d electronic states, NiFe bimetallic nanocatalysts with various content ratios were synthesized to evaluate their positive characteristics on the electrochemical NO₃RR. Eventually, the Ni_0.7Fe_0.3 sample inclined toward the cubic FeNi₃ structure was proven to have the best electrocatalytic NO₃RR performance: 13.61 mol g⁻¹ h⁻¹ ammonia production efficiency (APE) and 99.53% Faradaic efficiency (FE) under 1 M KNO₃ and 47.94 mmol g⁻¹ h⁻¹ APE and 95.04% FE under 1 mM KNO₃, superior to most reported electrocatalysts. Moreover, the above data outline the complete evolution of the distinct nitrogen-containing intermediate restricted by the NiFe-based asymmetric bridge structure.