Electrochemical removal of nitrate using Co/Ni bimetallic electrode: High N2 selectivity and long-term stability

The effectiveness of the electrochemical reduction of nitrate relies heavily on the N2 selectivity and stability of the cathode. In this study, we present a Co/Ni bimetallic electrode that was fabricated through an electrodeposition process and explored as cathode for the electrochemical reduction of nitrate. Electrochemical test demonstrated that vertical arrays of Co-containing nanosheets significantly improved electrochemical properties of Ni foam, particularly in terms of catalytic activity for nitrate. The removal rate of nitrate by this bimetallic foam electrode was 97.2% within 60 min, which is significantly better than that of Ni foam electrode (15.0%) and Co/Ni plate electrode (70.1%). This is attributed to the comprehensive enhancement of catalytic active sites, electrochemical activity, and nitrate affinity brought by the Co/Ni foam electrodes. The electrode demonstrated high nitrogen selectivity, achieving a total nitrogen removal rate close to 100%. The influence parameters and stability of the electrode were also evaluated, and a possible mechanism of nitrate removal was proposed. Significantly, this study presented novel opportunities for the advancement of effective bimetallic electrode materials intended for the reduction of nitrate.