A Dual‐Site Molecular System for the Electroreduction of Nitrate to Ammonia with Enhanced Activity and Selectivity

The electrochemical nitrate reduction reaction offers a promising route for sustainable ammonia synthesis and environmental nitrate remediation. However, the inherent complexity of the reaction, involving multiple electron‐proton transfer steps and diverse intermediates, poses significant challenges to achieving efficient and selective conversion. Herein, we report a molecularly well‐defined tandem catalyst that facilitates the stepwise optimization of nitrate‐to‐nitrite reduction followed by nitrite‐to‐ammonia conversion. Iron phthalocyanine (FePc) is initially identified for its superior nitrate adsorption capability, while the introduction of electron‐withdrawing cyano substituents (─CN) further lowers the reaction overpotential. The enhanced activities, however, result in the accumulation of the nitrite intermediate, which can be alleviated by the introduction of cobalt phthalocyanine (CoPc) sites with higher intrinsic activity toward nitrite reduction. The optimized catalyst with FePc─CN and CoPc co‐anchored on carbon nanotubes demonstrates highly selective ammonia production over a wide current density window. Mechanistic investigations reveal the tandem reduction pathway and highlight the critical role of proximal cooperation between the two active sites. This work presents a promising design strategy for tandem molecular catalysts in complex multistep electrocatalytic transformations.