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

Abstract

A detailed study of the electrochemical behavior of the Ce^4+/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) (ρ ≈ 15 mΩ 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, k⁰ was found to be almost one order of magnitude higher than at BDD, as a possible consequence of higher hydroxy group coverage.