Semiconductor Photocatalysis

Focusing on the basic principles of semiconductor photocatalysis, this book also gives a brief introduction to photochemistry, photoelectrochemistry, and homogeneous photocatalysis. In addition, the author - one of the leading authorities in the field - presents important environmental and practical aspects. A valuable, one-stop source for all chemists, material scientists, and physicists working in this area, as well as novice researchers entering semiconductor photocatalysis.

Auteur
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 fur Strahlenchemie (now Max-Planck-Institut fur Chemische Energiekonversion) in Mulheim 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-Nurnberg, 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.

Contenu

Preface XI

Acknowledgments XIII

1 Introduction 1

1.1 A Brief History of Photochemistry 1

1.2 Catalysis, Photochemistry, and Photocatalysis 5

2 Molecular Photochemistry 9

2.1 Absorption and Emission 9

2.2 Intensity of Electronic Transitions 14

2.2.1 Contribution of Nuclei 14

2.2.2 Contribution of Spin 17

2.2.3 Contribution of Orbitals 17

2.3 Excited States Radiative Lifetimes 17

2.4 Energy and Electron Transfer 19

2.4.1 Energy Transfer 19

2.4.2 Electron Transfer 21

2.5 Proton Transfer and Hydrogen Abstraction 23

2.6 Photosensitization 23

2.7 Rates and Quantum Yields 25

2.8 Quenching of Excited States 26

2.8.1 Identication of the Reactive Excited State 28

2.9 Absorption, Emission, and Excitation Spectra 28

2.10 Classication and Reactivity of Excited States 30

2.10.1 Organic Molecules 30

2.10.1.1 ,* States 30

2.10.1.2 n,* States 30

2.10.1.3 Charge-Transfer (CT) States 32

2.10.1.4 Triplet and Singlet Oxygen Reactions 36

2.10.2 Inorganic and Organometallic Complexes 38

2.10.2.1 Metal-Centered (MC) States 39

2.10.2.2 Ligand-Centered (LC) States 42

2.10.2.3 Charge Transfer Metal to Ligand (CTML) States 42

2.10.2.4 Charge Transfer Ligand to Metal (CTLM) States 42

2.10.2.5 Charge Transfer to Solvent (CTTS) States 43

2.10.2.6 Intervalence Transfer (IT) States 43

3 Molecular Photocatalysis 47

3.1 Hydrogenation of 1,3-Dienes 47

3.2 Co-Cyclization of Alkynes with Nitriles 47

3.3 Enantioselective Triuoromethylation of Aldehydes 48

3.4 Photoinduced Electron Transfer Catalysis 50

3.5 Reduction and Oxidation of Water 51

4 Photoelectrochemistry 55

4.1 Electronic Structure and Nature of Excited States 55

4.1.1 The (Optical) Bandgap 55

4.1.1.1 Measurement of the Bandgap Energy 58

4.1.1.2 Inuence of Crystal Size 63

4.1.2 The Photonic Bandgap 64

4.1.3 Emission Spectra 65

4.2 Photocorrosion 68

4.3 Interfacial Electron Transfer 70

4.3.1 Introduction 70

4.3.2 Thermal Interfacial Electron Transfer (IFET) 73

4.3.2.1 IFET at the Metal/Liquid Interface 73

4.3.2.2 IFET at the Semiconductor/Liquid Interface 76

4.3.3 Photochemical Interfacial Electron Transfer 78

4.3.3.1 IFET in Large Semiconductor Crystals 78

4.3.3.2 IFET in Small Semiconductor Crystals 82

5 Semiconductor Photocatalysis 85

5.1 Mechanisms, Kinetics, and Adsorption 85

5.1.1 General Classication of Reactions 85

5.1.2 Rates, Quantum Yields, and Their Comparability 91

5.1.2.1 Direct Semiconductor Photocatalysis 91

5.1.3 Inuence of Semiconductor Nature and Particle Size on Chemical Selectivity 108

5.1.3.1 Control of Chemoselectivity by Surface States and Redox Amplication 110

5.2 Characterization of Photocatalysts 111

5.2.1 General Methods 111

5.2.2 Flatband and Quasi-Fermi Potentials 112

5.2.2.1 Measurements in Absence of Light 112

5.3 Preparation and Properties of Photocatalysts 124

5.3.1 Pristine Compounds and Solid Solutions 128

5.3.1.1 TiO2 128

5.3.1.2 WO3 129

5.3.1.3 -Fe2O3 130

5.3.1.4 BiVO4 130

5.3.1.5 Ta2O3, TaON, Ta3N5, and MTaO2N 130

5.3.1.6 CuO, Cu2O 131

5.3.1.7 GaNZnO 131

5.3.1.8 CdS and ZnS 133

5.3.2 Grafting of CdS and TiO2 onto Inorganic Supports 133

5.3.2.1 Grafting onto a Nonconducting Support 133 <p&g...