Photocatalytic reaction kinetics on TiO2 thin films under light-limited and mass transport-limited conditions

This paper describes our recent studies on kinetics and mechanism of photoc atalytic decomposition of reactions on TiO2 thin films under weak UV illumi nation. Separate observation of reactions at oxidation and reduction sites of a photocatalyst indicated that the radical chain reactions occur at oxid ation sites during the photodegradation Of ethanol. The quantum yields (QY) for degradation of 2-propanol and acetaldehyde were determined by the norm alized absorbed photon number (I-norm). High QY values were obtained for ac etaldehyde in comparison to 2-propanol indicating the existence of radical chain reactions for the former reaction. Based on the kinetic studies of ga s phase 2-propanol degradation under wide range of light intensities and in itial concentrations, we have mapped various regions on a light intensity v s, initial reactant concentration plot, showing pure mass transport-limited conditions and pure light intensity-limited conditions.