Engineering asymmetric Co−O−Fe motifs with misaligned electronic environment toward near-unity nitrate-to-ammonia conversion

Electrocatalytic nitrate reduction (eNO₃⁻RR) is widely recognized as a sustainable strategy for green ammonia production. However, the complex adsorption–activation–hydrogenation behavior of multiple nitrogen-oxygen intermediates and the intrinsic mismatch in proton-coupled electron transfer kinetics severely hinder the NH₃ yield. Herein, a structurally engineered FeCo-MOF electrocatalyst featuring an asymmetric Co–O–Fe center was constructed via competitive coordination. The unique electronic orbital distribution in the Co–O–Fe bimetallic center promotes O-mediated charge transfer from Co to Fe. This charge redistribution induces enhanced electronic localization and asymmetry within the Co–O–Fe unit, thereby facilitating the activation and reduction of nitrogen-oxygen intermediates. Notably, in this asymmetric electronic configuration, the Co site enables efficient electron provisioning and promotes water dissociation to generate active hydrogen (H_ads) species, ensuring well-matched proton-coupled electron transfer kinetics and accelerating the rapid conversion of the key *NO intermediate on electron-enriched Fe sites. Theoretical calculations further demonstrate that the asymmetric Co–O–Fe motif significantly lowers the thermodynamic barrier of *NO → *NOH step. The catalyst delivers a NH₃ production rate of 0.653 mmol·cm⁻²·h⁻¹ (1306 mmol·g_cat⁻¹·h⁻¹) with a near-unity Faradaic efficiency (FE) of 99.8%. This study provides comprehensive insights into optimizing proton-coupled electron transfer dynamics and elucidating structure-performance relationships for advanced green-ammonia electrocatalysis.