Balancing Active Hydrogen and Nitrite Intermediates Adsorption on 3d Transition Metal‐Based Catalysts to Enhance Efficiency of Ammonia Production

Abstract Nitrate electroreduction (NO ₃ RR) is a green and efficient approach for ammonia production but encounters big challenges, including low Faraday efficiency (FE) and yield, which are caused by the difficult balance between active hydrogen (H*) and nitrite intermediate (NO ₂ *) production during NO ₃ RR process. Herein, theoretical calculations are first performed to study the effect of the balance between H* and NO ₂ * intermediates on ammonia production for various metal nanoparticles, followed by the synthesis of four representative metal (Ni, Fe, Co, Cu) catalysts based on calculation results. Among four catalysts, the Co@C catalyst exhibits the best NO ₃ RR performance with ultrahigh ammonia FE of ≈100% over a wide voltage range, high ammonia yield of 19874 µg h ⁻¹ cm ⁻² , and excellent long‐term stability. In situ Raman and electron microscope analyses reveal that the cobalt particles convert into cobalt hydroxide during electrocatalytic process, enhancing ammonia selectivity while suppressing the production of hydrogen and nitrite. More importantly, the Zn–NO ₃ ^– battery exhibited 160 h operation, illustrating superior stability. This work not only elucidates the effect of H* and NO ₃ H* intermediates on NO ₃ RR performance for ammonia production but also provides insights for the design of efficient electrocatalysts toward ammonia production and Zn–NO ₃ ^– battery.