Breaking the Activity–Stability Trade-Off in Electrochemical NO2– Reduction to NH3 over a Robust Fe3C/CN Catalyst

Electrocatalytic nitrite reduction coupled with plasma nitrogen oxidation offers a promising route for ambient ammonia synthesis, yet simultaneously achieving high activity and stability remains challenging owing to high kinetic barriers and catalyst deactivation. Here, we develop a robust hybrid electrocatalyst for active and durable nitrite reduction to ammonia by leveraging Fe3C nanoparticles supported on nitrogen-doped carbon nanosheets (Fe3C/CN). As a benefit from strong interactions between Fe3C and CN, this hybrid catalyst delivers a high faradaic efficiency of 89.6% at −0.7 V versus a reversible hydrogen electrode (vs RHE) and a record ammonia yield rate of 16 956.5 mmol h–1 gcat–1 at −0.9 V vs RHE, along with no apparent performance decay over 1000 h of continuous electrolysis, underscoring its potential for sustainable electrochemical ammonia production. Mechanistic studies reveal that the synergistic effect between Fe3C nanoparticles and a nitrogen-doped carbon matrix enhances catalytic performance by optimizing reactant adsorption, water dissociation, and promoting reaction kinetics.