Boosting ammonia production in electrocatalytic NO_x reduction on a robust Fe/FeMoO₄ catalyst

Electrocatalytic reduction of nitrate (NO₃⁻) and nitride (NO₂⁻) to ammonia (NH₃) is of wide interest as a promising alternative to the energy-intensive Haber-Bosch route for mitigating the vast energy consumption and the accompanied carbon dioxide emission, as well as benefiting for the relevant sewage treatment. However, exploring an efficient and low-cost catalyst with high atomic utilization that can effectively facilitate the slow multi-electron transfer process remains a grand challenge. Herein, we present an efficient hydrogenation of NO₃⁻/NO₂⁻ species to NH₃ in both alkaline and neutral environments over the Fe₂(MoO₄)₃ derived hybrid electrocatalyst with the metallic Fe site on FeMoO₄ (Fe/FeMoO₄). The Mo ingredient can play a synergistically positive role in further promoting the NH₃ production on Fe. As a result, Fe/FeMoO₄ behaves well in the electrochemical NH₃ generation from NO₂⁻ with a maximum NH₃ Faradaic efficiency (FE) of 96.53% and 87.68% in alkaline and neutral electrolyte, corresponding to the NH₃ yield rate of 640.68 and 302.56 mg·h⁻¹·mg_cat. ⁻¹, respectively, which outperforms the Fe and Mo counterpart and other similar catalyst, showing the robust catalytic capacity of each active site.