Recent Advances in Electrocatalytic Reduction of Nitrogen Oxides to Hydroxylamine.

Hydroxylamine (NH2OH) is a crucial intermediate in the global chemical industry, but traditional production methods heavily rely on fossil fuels and demanding reagents, leading to severe environmental pollution and energy consumption. Electrochemical reduction of reactive nitrogen oxides (NOx) offers a sustainable alternative, but its selectivity faces significant mechanistic challenges because the thermodynamically unstable NH2OH is easily over-reduced to ammonia (NH3). This review systematically investigated the current development for the electrochemical synthesis of NH2OH. First, the reaction mechanism was explained in detail with an emphasis on the *NHO pathway and linear adsorption configuration for maintaining the N─O bond. Second, the design strategies of various catalysts were surveyed. Furthermore, we discussed capture methods for NH2OH using ketones and aldehydes, which produces value-added oxime compounds while avoiding over reduction. Finally, outlooks were presented to guide further directions. We believe that the review will advance the future research and industrialization process of e-NOxR.