• Heterogeneous catalysis
• Photocatalysis

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Photocatalysis

Titanium dioxide is a semiconductor. The band spacing of the anatase modification of Eg = 3.2 eV, combined with the high oxidation potential of the valence bond, of approx. VVB=3.1eV (pH 0), make it possible to oxidize virtually any organic molecule under UV radiation (wavelength <390 nm).


Figure 1: Schematic of photocatalysis on a semiconductor



Figure 2: Photochemical breakdown of dichloroacetic acid

Potential applications therefore exist for titanium dioxide as a pollutant-degrading catalyst in waste-water treatment and air purification. An unusually high quantum yield for degradation of a range of halogenated hydrocarbons has been experimentally verified for Hombikat UV100. Dichloroacetic acid, for instance, is extremely effectively mineralized with a quantum yield of up to 16 %. These examinations were done by the Institut für Solarenergieforschung GmbH (ISFH), Hameln, Germany.