Selective electrocatalytic reduction of nitrate to dinitrogen by Cu2O nanowires with mixed oxidation-state

Selective electrocatalytic nitrate reduction reaction to dinitrogen is a promising water treatment technology to manage nitrate. While, a lack of efficient electrode remains the primary hurdle for achieving the goal. For non-noble electrode, the strong adsorption of oxygen atoms on Cu resulted in low selectivity and inducing nitrite accumulation during the long-term operation. Herein, it is found that Cu2O nanowires with mixed oxidation-state can selective reduction of nitrate to dinitrogen. CuO-coated Cu2O nanowires (CuO/Cu2O NWs) was electrochemically converted into Cu/Cu2O NWs for hydrogen/oxygen-adsorbing which was verified by In-situ infrared spectro-electrochemical experiments. H2 split and H*-adsorbing of Cu/Cu2O are desired to yield sufficient H* and limit hydrogen bubbles negative effect. Online differential electrochemical mass spectrometry confirmed dinitrogen generation over Cu/Cu2O NWs with over 99.8% selectivity. Computational studies suggest that active Cu/Cu2O NWs reduces the free energy changes associated with both nitrate activation and N − N coupling. Energetically favorable pathways for dinitrogen production based on nitrate reduction are proposed herein and the origin of this selective dinitrogen formation is clarified.