Surface Modified Titania Visible Light Photocatalyst Powders

Abstract

Titanium dioxide has received great attention both in fundamental and applied photocatalysis due to its low cost, non-toxicity, and stability against photocorrosion [ - ]. Unfortunately it can utilize only the very small UV part (about 3%) of solar light arriving at the earth surface. However, also the visible part (λ > 400 nm) may induce photocatalysis if titania is modified by transition or main group elements. Accordingly, many publications appeared in the last 20 years dealing with the problem of sensitizing titania for visible light photooxidation reactions. This may be achieved by doping, which means substitution of lattice ions, and by surface modification. In many cases authors not clearly differentiate between these two possibilities and so called doped titania quite often is a surface modified material. The latter is easily prepared by heating titania or its precursor compounds like titanium hydroxide in the presence of a modifier at temperatures in the range of 100 – 500 °C. In the following we summarize our work in this field using inorganic and organic sensitizers.