Factors Influencing Product Distribution in Photocatalytic Decomposition of Aqueous Acetic Acid on Platinized TiO2

Article abstract of DOI:10.1021/j100231a027

Reaction products of the photocatalytic decomposition of acetic acid/acetate mixtures at Pt/TiO2 were determined quatitatively for the gas phase and qualitatively for species in solution under a variety of experimental conditions.The relative yield of ethane to methane produced was high when the decomposition rate was high, and the amount of CO2 produced usually exceeded that of methyl radical consumed in the formation of methane and ethane.Analysis of the solutions revealed that ethanol and acetaldehyde were produced, and further oxidation of these substances seems likely to be least partly responsible for the excess production of CO2.The production of methane occurred even under conditions where the formation of adsorbed hydrogen was made insignificant by the preferential reduction reaction (Pd deposition) during the photodecomposition of acetic acid/ acetate mixtures.Electrolysis experiments at a single crystal TiO2 anode also showed that, even under very high anodic bias, where any cathodic reaction is completely suppressed, methane was prioduced with higher yields than ethane.The processes to account for these phenomena are discussed.