In recent years, semiconductor photocatalysis has become more
and more attractive and important since it has a great potential in
solving environmental problems. One of the most important
aspects of environmental photocatalysis is the selection of photoactive
materials. Semiconductor materials like ZnO and TiO2 are
two of the ideal photocatalysts in several respects. Both provide
photo-generated holes with high oxidizing power due to their wide
band gap energy and especially zinc oxide is relatively inexpensiveAs well-known photocatalyst, nanostructured ZnO has received
much attention in the degradation and complete mineralization of
environmental pollutants [1–4]. ZnO and TiO2 are the widely
studied metal-oxide semiconductors with a wide band gap of
3.2 eV and 3.3 eV, respectively [5]. Doping or dispersing it with