Semiconductor Photocatalysis

Horst Kisch studied chemistry at the University of Vienna, Austria, where he received his Ph.D. in 1969. From 1968 to 1984 he worked at the Max-Planck-Institut für Strahlenchemie (now Max-Planck-Institut für Chemische Energiekonversion) in Mülheim a.d. Ruhr, Germany. In 1977 he completed his "habilitation" in Organic Chemistry at the University of Dortmund, Germany, and became Professor of Inorganic Chemistry at the University of Erlangen-Nürnberg, Germany, 1984. He retired in 2008. His research interests were the catalytic activation of 1,2-diazenes by transition metals and physical consequences of weak charge-transfer interactions in redox active ion pair complexes. Recently he was engaged in new organic syntheses photocatalyed by semiconductor powders and in the photofixation of dinitrogen by nanostructured thin films.

• Preface XIAcknowledgments XIII1 Introduction 1 1.1 A Brief History of Photochemistry 11.2 Catalysis, Photochemistry, and Photocatalysis 52 Molecular Photochemistry 9 2.1 Absorption and Emission 92.2 Intensity of Electronic Transitions 142.2.1 Contribution of Nuclei 142.2.2 Contribution of Spin 172.2.3 Contribution of Orbitals 172.3 Excited States Radiative Lifetimes 172.4 Energy and Electron Transfer 192.4.1 Energy Transfer 192.4.2 Electron Transfer 212.5 Proton Transfer and Hydrogen Abstraction 232.6 Photosensitization 232.7 Rates and Quantum Yields 252.8 Quenching of Excited States 262.8.1 Identification of the Reactive Excited State 282.9 Absorption, Emission, and Excitation Spectra 282.10 Classification and Reactivity of Excited States 302.10.1 Organic Molecules 302.10.1.1 π,π* States 302.10.1.2 n,π* States 302.10.1.3 Charge-Transfer (CT) States 322.10.1.4 Triplet and Singlet Oxygen Reactions 362.10.2 Inorganic and Organometallic Complexes 382.10.2.1 Metal-Centered (MC) States 392.10.2.2 Ligand-Centered (LC) States 422.10.2.3 Charge Transfer Metal to Ligand (CTML) States 422.10.2.4 Charge Transfer Ligand to Metal (CTLM) States 422.10.2.5 Charge Transfer to Solvent (CTTS) States 432.10.2.6 Intervalence Transfer (IT) States 433 Molecular Photocatalysis 47 3.1 Hydrogenation of 1,3-Dienes 473.2 Co-Cyclization of Alkynes with Nitriles 473.3 Enantioselective Trifluoromethylation of Aldehydes 483.4 Photoinduced Electron Transfer Catalysis 503.5 Reduction and Oxidation of Water 514 Photoelectrochemistry 55 4.1 Electronic Structure and Nature of Excited States 554.1.1 The (Optical) Bandgap 554.1.1.1 Measurement of the Bandgap Energy 584.1.1.2 Influence of Crystal Size 634.1.2 The Photonic Bandgap 644.1.3 Emission Spectra 654.2 Photocorrosion 684.3 Interfacial Electron Transfer 704.3.1 Introduction 704.3.2 Thermal Interfacial Electron Transfer (IFET) 734.3.2.1 IFET at the Metal/Liquid Interface 734.3.2.2 IFET at the Semiconductor/Liquid Interface 764.3.3 Photochemical Interfacial Electron Transfer 784.3.3.1 IFET in Large Semiconductor Crystals 784.3.3.2 IFET in Small Semiconductor Crystals 825 Semiconductor Photocatalysis 85 5.1 Mechanisms, Kinetics, and Adsorption 855.1.1 General Classification of Reactions 855.1.2 Rates, Quantum Yields, and Their Comparability 915.1.2.1 Direct Semiconductor Photocatalysis 915.1.3 Influence of Semiconductor Nature and Particle Size on Chemical Selectivity 1085.1.3.1 Control of Chemoselectivity by Surface States and Redox Amplification 1105.2 Characterization of Photocatalysts 1115.2.1 General Methods 1115.2.2 Flatband and Quasi-Fermi Potentials 1125.2.2.1 Measurements in Absence of Light 1125.3 Preparation and Properties of Photocatalysts 1245.3.1 Pristine Compounds and Solid Solutions 1285.3.1.1 TiO2 1285.3.1.2 WO3 1295.3.1.3 α-Fe2O3 1305.3.1.4 BiVO4 1305.3.1.5 Ta2O3, TaON, Ta3N5, and MTaO2N 1305.3.1.6 CuO, Cu2O 1315.3.1.7 GaN–ZnO 1315.3.1.8 CdS and ZnS 1335.3.2 Grafting of CdS and TiO2 onto Inorganic Supports 1335.3.2.1 Grafting onto a Nonconducting Support 1335.3.2.2 Grafting onto a Semiconducting Support 1355.3.3 Grafting of Metal Halides and Metal Oxides onto Titania 1365.3.3.1 Metal Chloride-Grafted Titania 1365.3.4 Metal-Loaded Powders 1415.3.5 Nonmetal-Modified Titania 1415.3.5.1 Nitrogen-Modified Titania 1425.3.5.2 “Carbon”-Modified Titania 1465.3.5.3 Miscellaneous 1475.4 Type A Reactions 1485.4.1 WaterSplitting 1495.4.1.1 One-Particle Photocatalysis 1535.4.1.2 Two-Particle Photocatalysis 1555.4.1.3 Reduction and Oxidation of Water 1575.4.2 Aerobic Oxidations 1595.4.2.1 Direct Photocatalysis 1595.4.2.2 Indirect Photocatalysis 1655.4.3 Nitrogen Fixation 1655.4.3.1 Fixation by UV Irradiation 1655.4.3.2 Fixation by Visible Irradiation 1675.4.3.3 Formation of Ammonia, Hydrazine, and Nitrate 1695.4.3.4 Role of ChlorideIons 1715.4.3.5 Mechanism 1725.4.4 Carbon Dioxide Fixation 1735.4.5 Organic Reactions 1765.4.5.1 Oxidative C–N Cleavage 1775.4.5.2 Intramolecular C–N and C–C Coupling 1785.4.5.3 Intermolecular C–C and C–N Coupling 1785.4.5.4 Intermolecular C–O Coupling 1815.4.5.5 Anaerobic Dehydrodimerization and Intermediary Water Reduction 1825.5 Type B Reactions 1885.5.1 C–N Coupling 1885.5.2 C–C Coupling 1925.5.2.1 Addition of Olefins to Imines 1925.5.2.2 Addition of Olefins to Amines 1985.5.3 C–H Activation of Alkanes 1985.6 Environmental Aspects 2025.6.1 Abiotic Nitrogen Fixation 2025.6.2 Photocatalysis and Chemical Evolution 2035.6.3 Detoxification of Air and Water 2045.6.4 Antibacterial and Antiviral Effects 2045.6.5 Amphiphilic Properties of Titania 2055.7 Titaniain Food and Personal Care Products 2065.8 Photoreactors 2065.8.1 Laboratory Photoreactors 2065.8.2 Solar Photoreactors and Kinetic Modeling 208References 211Index 245