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International Journal of Photoenergy
Volume 3 (2001), Issue 1, Pages 1-16

Photo-induced processes in heterogeneous nanosystems. From photoexcitation to interfacial chemical transformations

1Department of Chemistry and Biochemistry, Concordia University, 1455 deMaisonneuve Blvd. West, (Quebec), Montreal H3G 1M8, Canada
2Department of Photonics, Institute of Physics, St. Petersburg State University, Ulyanovskaya 1, St. Petersburg, Russia
3Division of Chemistry, National Science Foundation, 4201 Wilson Blvd., Arlington, VA 22230, USA

Copyright © 2001 Hindawi Publishing Corporation. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


This article briefly reviews some of our recent work carried out both from an experimental point of view as well as from a theoretical perspective to gain further understanding of the events that take place in Heterogeneous Photocatalysis. Previously, the multitude of reports from our laboratory and from many others looked at the primary photocatalytic events as involving (a) absorption of light, (b) formation of the free (electrons and holes) and/or trapped charge carriers (Ti3+ and •OH radicals), and (c) reaction of pre-adsorbed acceptor or donor molecules with the relevant trapped carrier. Our recent work notes that this view is reasonable if the only purpose of photocatalysis is elimination of undesirable environmental pollutants. But when we begin to query how to render a process more efficient, we need to address the primary events following photoexcitation of the photocatalyst, which in most instances has been titanium dioxide (in the anatase form). Owing to the nature of light absorption by TiO2 we resorted to examining other metal oxides, most of which are dielectric insulators with very large bandgap energies, for example zirconia (ZrO2) and scandia (Sc2O3). These dielectrics have provided added information on the photophysical events, many of which are masked by the strong light absorption in titania. Despite some of our recent progress, much remains to be done for a fuller understanding of the events that occur at the surface, which we have often considered to be the greatest and most complex defect in metal oxide particulates.