Electrochemical reduction of nitrate in weakly alkaline solutions

The electrocatalytic activity of several materials for the nitrate reductio n reaction was studied by cyclic voltammetry on a rotating ring disc electr ode in solutions with different concentrations of sodium bicarbonate. Coppe r exhibited highest catalytic activity among the materials studied. Nitrate reduction on copper was characterized by two cathodic shoulders on the pol arization curve in the potential region of the commencement of hydrogen evo lution. In this potential range an anodic current response was observed on the Pt ring electrode identified as nitrite to nitrate oxidation. This indi cates that nitrite is an intermediate product during nitrate reduction. The se conclusions were verified by batch electrolysis using a plate electrode electrochemical cell. Copper and nickel, materials representing the opposit e ends of the electrocatalytic activity spectra, were used in batch electro lysis testing.