PARTICIPATION OF INCIPIENT HYDROUS OXIDE SPECIES IN ELECTROOXIDATION PROCESSES - A NOVEL VIEW OF ELECTROCATALYSIS AT NOBLE METAL ANODES.

The effect of microdispersion (or hyperextension) on the reactivity of oxides is frequently ignored. Solution species (H//2O, H** plus , OH** minus ) penetrate gel material and modify the redox behaviour of oxycations present. With noble metals, adatoms oxidize at potentials significantly lower than accepted thermodynamic values which refer to regular lattice species. Dissolved organics commence (anodic sweep) and terminate (cathodic) sweep) their oxidation at the reversible adatom/hydrous oxide potential; interfacial cyclic redox mechanisms, involving incipient hydrous oxide species, operate. These oxide species may not be vigorous oxidizers; reaction must be preceeded by activation of the organics. The marked electro-catalytic properties of some noble metals for electroorganic oxidation is due to their dual role: (1) activation due to adsorption or low oxidation state compound formation, followed by (2) oxidation state compound formation, followed by (2) oxidation associated with the presence of incipient hydrous oxide. This new view of noble metal electrocatalysis rationalizes many previously unexplained results.