Selective electron perturbation via oxygen vacancies enables efficient nitrogen electroreduction

Electrocatalytic nitrogen reduction reaction (NRR) offers a viable, energy-saving method for sustainable ammonia production. However, its practical application is severely limited by the inert N₂ molecules and the competing hydrogen evolution reaction (HER). Herein, oxygen-vacancy-rich FeMoO₄ nanoparticles (FMO-1) were rationally synthesized through a hydrothermal method followed by controlled Ar/H₂ etching. Structural and spectroscopic characterizations demonstrate that oxygen-vacancy formation predominantly reconstructs the electronic environment of Fe sites while preserving the Mo-O framework. This selective electronic perturbation elevates the Fe²⁺/Fe³⁺ ratio, enlarging the specific surface area, and enhancing N₂ adsorption capability. As a result, the optimized FMO-1 catalyst achieves approximately two-fold performance enhancements compared with pristine FeMoO₄. Further mechanism analysis reveals that oxygen vacancy significantly strengthens N₂ adsorption and activation on Fe sites. Besides, the selective Fe-centered electronic reconstruction effectively regulates the competitive adsorption behavior between NRR and HER, thereby improving ammonia selectivity. This work highlights the critical role of site-selective oxygen vacancy engineering in tuning competitive adsorption thermodynamics, and demonstrates a feasible route for rationally designing bimetallic oxide catalysts for ambient ammonia electrosynthesis. © 2026 Elsevier Inc.