Photocatalytic Formation of Hydrogen Peroxide in Aqueous Suspensions of Titanium Dioxide Supported with Palladium

This paper shows the results of a study on hydrogen peroxide formation in aqueous suspensions of anatase or rutile titanium dioxide with palladium particles deposited on its surface under the action of UV radiation. The formation of peroxide species on the photocatalyst surface was confirmed by IR spectroscopy, and the quantitative determination of hydrogen peroxide in solution was carried out by a colorimetric method using a special reagent containing peroxidase. To determine the pathway of peroxide compound formation, the effect of the composition of the gas phase (Ar, O-2) and liquid (water or aqueous methanol solution) on the accumulation of H2O2 was studied. The Pd-modified photocatalyst based on rutile exhibited significantly higher activity compared to that of the anatase-based photocatalyst. In both cases, the highest yield of H2O2 was achieved due to oxygen photoreduction upon the addition of methanol as an additional electron donor, which provided an increase in the rate of hole transfer as a rate-limiting step.