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.

Efficient oxygen electrocatalysts are the key elements of numerous energy storage and conversion devices, including fuel cells and metal–air batteries. In order to realize their practical applications, highly efficient and inexpensive non-noble metal-based oxygen electrocatalysts are urgently required. Herein, we report a novel iron-chelated urea-formaldehyde resin hydrogel for the synthesis of Fe-N-C electrocatalysts. This novel hydrogel is prepared using a new instantaneous (20 s) one-step scalable strategy, which theoretically ensures the atomic-level dispersion of Fe ions in the urea-formaldehyde resin, guaranteeing the microstructural homogeneity of the electrocatalyst. Consequently, the prepared electrocatalyst exhibits higher catalytic activity and durability in the oxygen reduction (ORR) and evolution (OER) reactions than the commercial Pt/C catalyst. Furthermore, the above catalyst also shows a much better performance in rechargeable Zn–air batteries, including higher power density and better cycling stability. The developed synthetic approach opens up new avenues toward the development of sustainable active electrocatalysts for electrochemical energy devices.