Electrochemical reduction of NO3− and NO2− on a composite copper thallium electrode in alkaline solutions

The electrochemical behaviour of the copper–thallium composite film has been investigated in 10 mM NaOH solutions towards the electroreduction of nitrate and nitrite ions in the range of potentials between 0.0 and −1.4 V vs. SCE. The Cu45Tl55 binary films exhibited a higher electrocatalytic activity for the reduction of NO3− and NO2− than pure copper and thallium electrodeposited films. The presence of thallium species in the composite film causes a marked increase of the roughness factor with subsequent increase of the catalytic response due to the nitrate and nitrite reduction. Alternatively, thallium particles act as promoters of NO3− and NO2− adsorption on the electrode surface with their subsequent accumulation on the surface catalytic centres and increase of the cathodic currents. pulsed chronoamperometric detection (PCD) using a selected waveform of potentials of 0.0 V (Eads) for 200 ms (tads) and −1.3 V (Edet) for 400 ms (tdet), the Cu45Tl55 composite electrode exhibits interesting cathodic currents upon nitrate and nitrite addition. The detection limits (S/N=2), evaluated in PCD conditions for nitrate and nitrite ions were 190 and 250 μM, respectively.