PHOTOELECTROCHEMICAL OXIDATION OF FORMATE IONS ON NICKEL-TITANIUM DIOXIDE NANOCOMPOSITE ELECTRODES - UNUSUALLY HIGH-CURRENT DOUBLING YIELDSAND MANIFESTATION OF A SITE PROXIMITY EFFECT

This paper concerns the photoelectrochemical oxidation of formate and acetate ions on nanocrystalline composite (nanocomposite) films compri sing of TiO2 and nickel. The photocurrents arising from the oxidation of these organic compounds were compared with those measured in the ba se electrolyte (0.1 M NaNO3), and a photocurrent enhancement factor, F was thus determined. Values off as high as ca. 5.5 were obtained for formate under certain conditions. The influence of film deposition tim e and TiO2 dose on F is described. The variation off with these film p reparation variables and the unusually high values of F for these nano composite films are rationalized on the basis of a site proximity effe ct that arises from the synergistic presence of both nickel as a subst rate adsorption site and adjoining TiO2 serving as the photocatalyst.