Heterogeneous Photocatalysis for Selective Oxidations with Molecular Oxygen

The significant features of photocatalysts consisting of inorganic compounds with well-defined textural characteristics, dispersed on high surface area solid supports or constrained inside their porous network, are summarized and discussed. These systems are based on the use of titanium dioxide, highly dispersed oxides and polyoxotungstates. They share similar primary photoprocesses: light absorption induces a charge-separation process with formation of positive holes able to oxidize organic substrates. We discuss chemical transformations carried out in the presence of O2 for inducing partial oxidation of alcohols and monooxygenation of hydrocarbons. We emphasize that the optimal tailoring of the photoactive materials for synthetic purposes can be achieved by combining recent advances in the preparation of nanostructured materials with mechanistic knowledge derived from surface science and molecular-level investigations.