Electrochemical reduction of nitrate and nitrite in alkaline media at CuNi alloy electrodes

The performances of electrodeposited CuNi alloys in the electrochemical reduction of nitrates and nitrites in alkaline electrolyte have been studied and compared with those of the individual metals. CuNi alloys have been deposited from a citrate bath and characterized by SEM–EDS: a large range of compositions (30–95 Cu at.%) was prepared by varying the deposition potential. Application to the electrochemical reduction of nitrate (and nitrite) shows that Cu-rich alloys (Cu = 70–95 at.%) work better than Cu: voltammetric waves show a lower overpotential in the order of 120–150 mV at fresh electrodes; chronoamperometries show higher initial currents and less severe current decay during prolonged polarization; electrolyses reduce more rapidly and with a better selectivity nitrate to ammonia.