Photocatalysis on Solid Catalysts
Irradiation of a semiconductor photocatalyst with light of appropriate wavelength results in the excitation of an electron from the valence band into the conduction band, leaving a positively charged hole in the valence band. This electron then can be transferred to an electron acceptor whereas an electron from a donor recombines with the hole in the valence band. In this manner, redox reaction can be catalyzed on the surfaces of semiconductors, such as for example TiO2 or ZnO. Combining semiconductor properties with specific steric arrangements within the pores of nanoporous solids appears a promising approach to tune the photocatalytic properties of such solids.