Boosting electrochemical nitrate-to-ammonia conversion by self-supported MnCo₂O₄ nanowire array

Direct electrocatalytic reduction of nitrate (NO₃^-) is an efficient route to simultaneously synthesize ammonia (NH₃) and remove NO₃^- pollutants under ambient conditions, however, it is hindered by the lack of efficient and stable catalysts. Herein, a self-supported spinel-type MnCo₂O₄ nanowire array is demonstrated for exclusively catalyzing the conversion of NO₃^- to NH₃, achieving a high Faradic efficiency of 97.1% and a large NH₃ yield of 0.67 mmol h^-1 cm^-2. Furthermore, density functional analysis reveals that MnCo₂O₄ (220) surface has high activity for NO₃^- reduction with a low energy barrier of 0.46 eV for *NO to *NOH.