ELECTROCHEMICAL AND XPS CHARACTERIZATION OF COMPOSITE MODIFIED ELECTRODES OBTAINED BY NICKEL DEPOSITION ON METALS.

A chemically modified electrode composed of nickel oxyhydroxide film deposited on noble metals (i.e., gold or platinum) was characterized in an alkaline medium by cyclic voltammetry and XPS (X-ray photoelectron spectroscopy) techniques. The nickel was deposited on the gold substrate in an alkaline medium by various strategies: cycling the potential between -0.1 and 0.65 V vs SCE, in potentiostatic conditions at potentials comprised between 0.0 and 0.55 V and by simple immersion of the electrode in non-deaerated 0.2 M NaOH solutions containing 3 mM K2Ni(CN)(4). The effects of several experimental parameters such as applied potentials, pH, tetra-cyanonickelate concentration, electrode substrate, etc., on the nickel film formation and growth were evaluated. The electroactivity of the resulting composite gold-nickel electrode was investigated in an alkaline medium toward the oxidation of carbohydrates using arabinose as a model compound