Electrochemical characterization of cobalt cordierites attached to paraffin-impregnated graphite electrodes

The electrochemistry of , and cobalt-containing cordierites (Co₂Al₄Si₅O₁₈) attached to paraffin-impregnated graphite electrodes has been studied by linear scan and cyclic voltammetries in HCl+NaCl and NaOH electrolytes. This electrochemistry is compared with that of vitreous cobalt cordierite, cobalt(II) oxide and cobalt spinel aluminate (CoAl₂O₄), the two last taken as reference materials. Electrochemical processes involve the site-characteristic reduction of Co(II) species to cobalt metal near to –0.5 V vs. SCE and their oxidative dissolution near +0.3 V, accompanied by solid state interconversion between Co(II) and Co(III) at potentials above +0.45 V. Cordierite-modified electrodes display a significant site-dependent catalytic effect on the electrochemical oxidation of mannitol in 0.10 M NaOH.