Electrosynthesis of hydroxylamine from nitrate reduction in water

Hydroxylamine(NH2OH), a vital but unstable industrial feedstock, is presently prepared under harsh conditions that cause environmental and energy concerns. Here, we report an electrochemical method to prepare oximes, which serve as precursors for NH2OH after facile hydrolysis. The carbon-supported amorphous Mn electrocatalyst delivers a current density of ～100 m A cm-2with a Faradaic efficiency of 40.92% and a yield rate of 0.251 mmol cm-2h-1for formaldoxime(CH2NOH) generation by using nitrate and formaldehyde as reactants. Formaldoxime can be easily released to produce NH2OH via hydrolysis. Impressively, this method exhibits an economic advantage over conventional manufacturing based on techno-economic analysis. A series of control experiments, in situ characterizations, and theoretical simulations unveil the reaction mechanism via the spontaneous reaction between an aldehyde and *NH2OH intermediate derived from nitrate electroreduction. The high activity of Mn originates from its inhibitory effects on the further reduction of key *NH2OH intermediate. This strategy opens a sustainable and green way for NH2OH synthesis under mild conditions using renewable energy.