Photoelectrochemical Degradation of 4-Chlorocatechol at TiO_2 Electrodes: Comparison between Sorption and Photoreactivity

The TiO_2-catalyzed photodegradation of a strongly adsorbing substrate, 4-chlorocatechol, has been investigated as a function of solution concentration and pH at illuminated polycrystalline TiO_2 electrodes operated at a constant current density. The results are compared to the previously determined sorption behavior of 4-chlorocatechol. The initial rates of 4-chlorocatechol photodegradation measured at pH 3, 5, and 8 and solution concentrations of 20, 50, and 200 μM show a linear correlation with the concentration of the sorbed substrate.