Heterogeneous Photo- and Thermal Catalytic Oxidation of CO: Effects of Metal Deposition

摘要

In an effort to elucidate the mechanism of rate enhancement of photocatalytic reactions over TiO_2 upon metal doping, CO oxidation reaction was studied under dark and illuminated conditions. It was observed that the rate enhancement due to the presence of Pt was merely due to the thermal reactions with no contribution from UV illumination under the sensitivity conditions of the experiments. Oxygen adsorption studies performed separately indicated that the oxygen adsorption capacity of the TiO_2 catalysts decreased after wetting and drying. Among differently pre-treated Pt containing catalysts, all of the samples exhibited a higher oxygen adsorption capacity than the TiO_2 substrate, except a sample for which the last treatment step was calcination. The results of this study indicate that the thermal catalytic effect of Pt is the only source of rate enhancement of CO oxidation, within the specified conditions.