Electrochemical and XPS characterization of composite modified electrodes obtained by nickel deposition on noble metals

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