Abstract: The kinetics and mechanism of the photoelectrocatalytic degradation of glucose with weak adsorption and potassium hydrogen phthalate with strong adsorption on a self-organized and highly ordered TiO₂ nanotube array (TNA) were investigated using a thin layer reactor in which the organic compounds were completely and quickly oxidized. The photogenerated current-time (I-t) profiles were used to analyze the microprocesses of the photoelectrochemical catalytic degradation on the TNA electrode. For glucose the I-t curve increased sharply initially and then decreased rapidly followed by a slow decrease. This is due to the weak adsorbability of glucose and it adsorbed slowly onto the surface of the TNA electrode from the bulk solution. However, the I-t curve for potassium hydrogen phthalate had quite a different trend as it increased sharply initially and then continued to increase and then decreased slowly and this was due to the strong adsorbability and mass existence of potassium hydrogen phthalate on the electrode and, in addition, the low degradability of phthalic acid. The adsorption properties and adsorption coefficient of the organic compounds and the reaction mechanism were also analyzed. We conclude that the obtained photoelectrocatalytic oxidation rate of the organic compounds in the thin-layer cell assisted in determining the surface reaction process and the micro-mechanism of organic compound degradation on the TNA electrode.

Key words: Glucose, potassium hydrogen phthalate, TiO2 nanotube array electrode, Thin-layer cell