Catalytic and photocatalytic effects on photoplatinized macroscopic TiO2 photoanodes in dilute ethanol solutions

TiO₂, platinized TiO₂, and platinized Pt anodes have been studied in both acidic and basic electrolytes in the presence of ethanol. In the case of macroscopic platinized TiO₂ anodes, the oxidation of ethanol to acetaldehyde and the further oxidation of acetic acid is predominantly a catalytic rather than a photocatalytic effect, and can be accomplished in the dark with a bias voltage of approximately 0.6 V. This same result has been shown to occur with platinized Pt electrodes in the absence of TiO₂. Cyclic voltammetry studies suggest that oxidation of acetic acid, previously reported in particulate platinized TiO₂ systems, requires the production of the highly reactive OH radical. Thus both catalytic and photocatalytic processes are occuring simultaneously at illuminated platinized TiO₂ anodes.