Sustainable manufacture of a directly accessible liquid nitrogenous fertilizer

Abstract Nitrogen fertilizer, the most commonly used fertilizer, plays a significant role in agriculture. The conventional production and usage of solid nitrogenous fertilizers result in severe energy consumption and groundwater pollution. Here, we construct a plasma−driven nitrogen fixation and membrane−free electrolysis relay system to continuously manufacture directly accessible liquid fertilizer (NH₄NO₃ solution) without any other additive ions; this system can be utilized by crops with high efficiency. RuCo−based powders are chosen as model catalysts. Ru₉Co₉₁Ox possesses the optimal plasma-catalytic ability, while Ru₉Co₉₁ exhibits the highest electro-catalytic activity. ¹⁵N isotope labelling experiments and a series of in situ characterizations unveil the electroreduction mechanism and N−contribution of NO/NO₂/NO₂⁻/NO₃⁻, which directs the establishment of a nitrogen balance between two relay processes. Impressively, a 20 L plasma reactor combined with an 8 L membrane−free electrolyzer is employed for the pilot−plant test, which outputs 4 L h⁻¹ NH₄NO₃ solution at a constant concentration (840 ppm−N) to meet the N−fertilizer requirement in a 50 m² farmland.