Electrocatalytic Oxidation of Methanol on the Ni-Co/ Gr Modified Glassy Carbon Electrode in Alkaline Medium

In this work, Ni-Co alloy on Graphene (Ni-Co/Gr) on the surface of glassy carbon (GC) electrode was performed by cyclic voltammetry. The results showed that the deposition of Ni -Co is an anomalous process, i.e. the ratio of Ni-Co in alloy is not equal as in the deposition bath. The deposition bath was prepared according to the metal ion Ni/Co ratio of 4: 1 using NiS04. 7H20 and CoS04.8H20, and the total concentration of all solutions was 40.0 mM. The pH of the bath solution was adjusted at 2.0 using boric acid at room temperature. It was shown that during the increase of cycle number, the thickness of the deposited fihn increased. The modified electrode was conditioned by potential recycling in a potential range of 100-700 mV (vs. SCE) by cyclic voltammetry method in an alkaline solution. The Ni-Co/ Gr modified electrode showed a higher activity towards methanol oxidation in the Ni (Ill) and Co (IV) oxidation states. Cyclic voltammetry was used for the electrochemical characterization of the NiCo/ Gr modified electrode and the mechanism of methanol oxidation is proposed. Moreover, the effects of various parameters such as mole ratio of Ni-Co in the alloy in modification step, potential scan rate, methanol concentration and solution temperature on the electro-oxidation of methanol have also been investigated.