Efficient electrolytic conversion of nitrogen oxyanion and oxides to gaseous ammonia in molten alkali

Electrochemical ammonia synthesis (EAS) and nitrogen oxyanion / nitrogen oxides (NO x − /NO x ) conversion are important aspects of the artificial nitrogen cycle. Herein, we report a molten alkali electrolysis reactor for converting NO x − /NO x to NH 3 . A 110.3 ± 4.7 mg · h −1 · cm −2 yield of ammonia synthesis from nitrite was achieved with the Faradaic efficiency close to 100 %. By coupling NO oxidation with NO x − reduction, the NO conversion above 99 % was achieved with ammonia yield of 57.75 mg · h −1 · cm −2 . More importantly, the produced ammonia can escape from the electrolyte, thus avoiding the energy-consumed separation process. Revealed by density functional theory calculations, the excellent activity of EAS can be attributed to low barriers of electrochemical hydrogenation and the facile breaking of N O bonds with the assistance of Na/K cation at the interface. This work opens a new sight in EAS and enriches the artificial nitrogen cycle.