Electrochemistry of the aqueous ceric/cerous redox couple at conductive diamond and gold electrodes

A detailed study of the electrochemical behavior of the Ce4+/3+ redox couple has been performed, in order to attempt a rationalization of the electron transfer at strongly positive potentials. Experiments have been carried out at highly boron-doped diamond (BDD) (rho approximate to 15 mOmega cm) and polycrystalline gold, in aqueous 1 M HClO4. The influence of temperature on the electron transfer kinetics has also been investigated at both electrode materials, thus allowing a comparison that practically confirms the metal-like properties of BDD as an electrode, in spite of its being a highly doped, semi-conductor. The electron transfer rate was only slightly affected by the degree of hydrophilicity of the diamond surface. At polycrystalline gold surfaces, which are oxidized under the required experimental conditions, k(0) was found to be almost one order of magnitude higher than at BDD, as a possible consequence of higher hydroxy group coverage.