Electrocatalytic oxidation of glucose on Ni and NiCu alloy modified glassy carbon electrode

Nickel and nickel-copper alloy modified glassy carbon electrodes (GC/Ni and GC/NiCu) prepared by galvanostatic deposition were examined for their redox processes and electro-catalytic activities towards the oxidation of glucose in alkaline solutions. The methods of cyclic voltammetry (CV) and chronoamperometry (CA) were employed. The cyclic voltammogram of NiCu alloy demonstrates the formation of beta/beta crystallographic forms of the nickel oxyhydroxide under prolonged repetitive potential cycling in alkaline solution. It is also observed that the overpotential for O(2) evolution increases for NiCu alloy modified electrode. In CV studies, NiCu alloy modified electrode yields significantly higher activity for glucose oxidation compared to Ni. The oxidation of glucose was concluded to be catalyzed through mediated electron transfer across the nickel hydroxide layer comprising of nickel ions of various valence states. The anodic peak currents show linear dependency with the square root of scan rate. This behavior is the characteristic of a diffusion-controlled process. Under the CA regime, the reaction followed a Cottrellian behavior, and the diffusion coefficient of glucose was found to be 1 x 10(-5) cm(2) s(-1), in agreement with diffusion coefficient obtained in CV studies.