The electrochemical reduction of nitrate ion on polypyrrole coated copper electrode

•Reduction of NO3− ion was investigated on a Cu and PPy–Cu in acidic aqueous medium.•Experiments were performed at different NO3− concentrations, pH, thicknesses and at potentials.•On PPy–Cu electrode, ammonia formed at the low overpotential region (−0.4 V; −0.8 V).•On PPy–Cu electrode, the reaction obeys to a simple electrochemical hydrogenation.

Reduction of nitrate ion was investigated on copper and polypyrrole coated copper electrode (PPy–Cu) in acidic aqueous medium. The nitrate concentration was increased, from 5 to 200 Mm (0.1 M LiClO4 + 0.001 M HClO4 + x mM KNO3; x = 5, 20, 50, 100 and 200 mM). The applied potentials were −0.4, −0.6, −0.8, −1.0 and −1.2 V [Ag/AgCl]. Depending on these parameters, nitrate reduction gave the same products with different concentrations on blank Cu and on PPy–Cu. On blank Cu, nitrite ion was formed under almost any condition whereby on PPy–Cu, ammonia was the main product. Especially at low overpotentials, such as −0.4, −0.6 and −0.8 V no nitrite was detected on PPy–Cu which leads to the conclusion that the coating of the surface changes the reaction mechanism.

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