Electrocatalytic reduction of nitrate using Mg(OH)₂ copper modified electrode

In order to improve the activity of copper (Cu) towards electrolytic reduction of nitrate, thin films of magnesium hydroxide (Mg(OH)₂) were deposited on Cu substrate. For the first time, these films were synthesized by electrochemical deposition in a potassium sulfate bath containing Mg²⁺ at 70 °C. The effect of various experimental parameters, such as deposition time and potential, on the electrocatalytic activity for the nitrate reduction was investigated. Surface analysis techniques (SEM, EDX and XRD) were used to get information on the morphology, the composition and the structure of the deposits. The activity of the modified electrode was studied by cyclic voltammetry, and amperometric method. The modified Mg(OH)₂/Cu sensor exhibited a good electrocatalytic behavior towards the reduction of nitrates with high reproducible reduction peak currents. In addition, the sensor exhibits a linear answer for concentration in nitrate between 0.125 to 7 mM, combined with high sensitivity (24.6 µA mM⁻¹ cm⁻²) and limit of detection (225.35 µM) values. When common interfering molecules were added to the solution, Mg(OH)₂/Cu electrodes have kept their good selectivity. They demonstrated acceptable detection levels for nitrates in tap water.