Electrocatalytic Properties of Nickel(II) Hydrotalcyte-type Anionic Clay. Application to Methanol and Ethanol Oxidation.

Glassy carbon electrodes modified with a [Ni/Al-Cl] hydrotalcite-type anionic clay have been studied with respect to the electrochemical oxidation of the NI(II) centres. The oxidation of Ni(II) is quasi-reversible and the presence in the hydrotalcite lattice of nickel with mixed oxidation states increases the conductivity of the coverage strongly. It has been verified that these nickel redox systems may act as redox mediators for the oxidation of alcohol substrates (methanol and ethanol have been tested) which are not oxidised at the bare electrode in the potential window available. For both alcohols the height of the current responses in linear sweep voltammetry is roughly linear with varying concentration in solution up to a limit of ca. 3000 ppm, with a detection limit of 3-4 ppm.