Embedded Fe‐Cu Pairs Enable Tandem Nitrate‐to‐Ammonia Electroreduction

Abstract

Abstract Electrochemical nitrate reduction ( e ‐NO 3 RR) to ammonia (NH 3 ) represents a transformative technology that seamlessly integrates environmental remediation with resource regeneration. This approach is crucial for restoring equilibrium in the global nitrogen cycling, advancing green chemistry, and accelerating the transition toward a sustainable circular economy. However, under pH‐neutral conditions, the simultaneous occurrence of two competing reactions (Hydrogen Evolution Reaction and NO 3 RR) at the same active sites results in considerable interference, significantly limiting the catalytic efficiency and selectivity. Here a Fe‐Cu pair (Cu‐N 3 /Fe 3 ‐N 8 ) electrocatalyst is meticulously designed, achieving a NH 3 production rate of 18.83 mg∙h ‒1 ∙mg cat ‒1 at −0.65 V versus the reversible hydrogen electrode (RHE), accompanied with a Faradaic efficiency of 97.1%. This as‐prepared Fe‐Cu pair overcomes the limitations of conventional bimetallic catalysts, which typically rely on direct atomic coupling. The electron‐deficient region formed by Cu–N 3 enhances the adsorption of nitrate, while the electron‐rich domain generated by the Fe 3 –N 8 cluster facilitates the adsorption of nitrite and promotes water activation. The spatially separated charge gradient optimizes the adsorption energies of multi‐step reaction intermediates, thereby establishing a relay mechanism. The work provides valuable insights into the design of multi‐active‐site electrocatalysts and offers a promising approach to addressing critical challenges in nitrogen resource conversion.