Semiconductor Photocatalysis for Atom-Economic Reactions

Based on preceding work on photoelectrochemistry at semiconductor single crystal electrodes the field of photocatalysis at semiconductor powders has experienced a tremendous growth in the last three decades. The reason for this is the genuine property of inorganic semiconductor surfaces to photocatalyze concerted reduction and oxidation reactions of a great variety of electron donor and acceptor substrates. Whereas high attention was paid to water splitting and exhaustive aerobic degradation of pollutants, only a small part of research explored synthetic aspects. After introducing the basic mechanistic principles, standard experiments for the preparation and characterization of visible light active photocatalysts and for the investigation of reaction mechanisms are discussed. Novel atom-economic C–C and C–N coupling reactions illustrate the relevance for organic synthesis. They exemplify that the multidisciplinary field of semiconductor photocatalysis combines classical photochemistry with electrochemistry, solid state chemistry, and heterogeneous catalysis.