Electrocatalysis of anodic oxygen-transfer reactions at modified lead dioxide electrodes

摘要

The electrocatalytic activities were compared for pure and chloride-doped beta-PbO(sub 2) (Cl-PbO(sub 2)) films on gold and platinum substrates. Rate constants were increased significantly for oxidations of Mn(sup 2+), toluene, benzyl alcohol, dimethylsulphoxide (DMSO) and benzaldehyde in acidic media by the incorporation of Cl(sup (minus)) into the oxide films. These reactions are concluded to occur by the electrocatalytic transfer of oxygen from H(sub 2)O to the reaction products. Results of x-ray diffraction studies indicate the Cl-PbO(sub 2) film continues to have the slightly distorted rutile structure of pure beta-PbO(sub 2). The observed electrocatalytic phenomena are concluded to be the beneficial consequence of surface defects generated when Cl(sup (minus)) serves for charge compensation within the surface matrix and, thereby, increases the number of surface sites capable of adsorbing hydroxyl radicals which are transferred in the electrocatalytic O-transfer reactions. 91 refs., 44 figs., 10 tabs.