Title: An MOF-derived C@NiO@Ni electrocatalyst for N₂ conversion to NH₃ in alkaline electrolytes

Abstract: Today, industrial ammonia synthesis mainly depends on the Haber–Bosch process, which causes a lot of energy consumption and huge CO₂ emissions. The electrochemical N₂ reduction reaction (NRR) is considered a more sustainable and environmentally benign alternative to produce ammonia, but it requires an efficient catalyst to overcome the difficulty of N₂ activation. In this work, we reported that MOF-derived C@NiO@Ni microtubes behaved as a high-efficiency electrocatalyst in 0.1 M KOH electrolyte. This electrocatalyst achieved a high NH₃ yield of 43.15 μg h⁻¹ mg_cat.⁻¹ and faradaic efficiency of 10.9% at −0.7 V vs. a reversible hydrogen electrode. The experimental results indicated that the excellent NRR performance originated from the oxygen vacancies in NiO. Moreover, the abundant NiO/Ni interfaces were conducive to proton adsorption and further enhanced the NRR performance.