Photoinduced phenomena on the surface of wide-band-gap oxide catalysts

This article reviews papers devoted to the investigation of photoinduced pr ocesses on non-semiconductor oxide catalysts. The main results of our ESR i n situ studies of such systems are presented. Wide-band-gap oxides are show n to constitute a new and very promising class of photocatalysts capable of functioning under illumination with visual light. It is shown that in many cases the light is initially absorbed by charge transfer complexes with th e following generation of ion-radical intermediates with high reactivity. A very important feature of photoinduced reactions in the absorption band o f charge transfer complexes is a significant shift of their red edge to lon ger wavelengths in comparison with similar processes in homogeneous systems . In many cases, the formation of such complexes is caused by the existence of strong acceptor or donor sites typical for many oxide catalysts with pr onounced acidic or basic properties. (C) 2000 Elsevier Science B.V. All rig hts reserved.