Selective electrocatalytic reduction of nitrate for the synthesis of hydroxylamine with Cu-ZnO/N-C catalyst

Electrocatalytic reduction of nitrate for the synthesis of high-value chemical hydroxylamine (NH 2 OH) represents a sustainable pathway that combines the dual functions of green synthesis and wastewater treatment. However, the selective control of the process is extremely challenging, mainly due to the susceptibility of nitrate to over-reduction during the reaction, leading to uncontrolled conversion of the target product NH 2 OH to the thermodynamically stable product ammonia (NH 3 ). In this paper, the Cu-PDA MOF precursor was synthesized using the emulsion method, and ZIF-8 was introduced to form the structure of Cu-PDA@ZIF-8. Subsequently, the nitrogen-carbon-doped Cu-ZnO/N-C catalysts were formed by calcination under N 2 atmosphere. The synthesized catalyst effective improved NH 2 OH selectivity during nitrate reduction. The NH 2 OH yield and FE efficiency of Cu-ZnO/N-C reached 564.97 μmol h −1 mg cat −1 and 46.64 %, respectively, under neutral electrolyte conditions. Cu, as the main component of the catalyst, plays a dominant role in hydroxylamine by electrocatalytic nitrate reduction to promote the reaction in the stage of NO 3 – →*NH 2 OH. Zn, on the other hand, plays a key role in the phase *NH 2 OH → NH 2 OH, selectively generating the product NH 2 OH and blocking the excessive reduction of NH 2 OH to NH 3 . Additionally, this study achieved tandem catalytic selective generation of NH 2 OH at copper and zinc heterogeneous interfaces and offers a potential approach and reference for applications involving the nitrate reduction reaction.