A systematic study on the effect of OH− and Ni2+ ions on the electro-catalytic oxidation of methanol at Ni-S-1 electrode

The effect of varying nickel ions as well as OH− ions concentration on the electrochemical oxidation of methanol on nickel impregnated silicalite-1 (Ni-S-1) electrodes was investigated. The study of nickel ions concentration effect was carried out in two different ways: by varying the soaking time in one and the same concentration of NiSO4 solution, or by fixing the soaking time in different concentrations of NiSO4 solution. The results showed that for electrodes pre-soaked in 1.0 M NiSO4 solution for 90 s, increasing the OH− ions concentration results in increasing the oxidation current density of methanol. On the basis of this result, high concentration of KOH is preferable as a medium for methanol oxidation at the Ni-S-1 electrode in presence of nickel ions. On the other hand, at a certain OH− ions concentration, the peak height of methanol oxidation increases with increasing Ni ions concentration up to a certain value after which no effect was observed. A first order reaction kinetics with respect to both nickel ions and OH− ions was estimated for the oxidation of methanol.