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Journal ArticleDOI

Environmental Applications of Semiconductor Photocatalysis

01 Jan 1995-Chemical Reviews (American Chemical Society)-Vol. 95, Iss: 1, pp 69-96

AbstractThe civilian, commercial, and defense sectors of most advanced industrialized nations are faced with a tremendous set of environmental problems related to the remediation of hazardous wastes, contaminated groundwaters, and the control of toxic air contaminants. For example, the slow pace of hazardous waste remediation at military installations around the world is causing a serious delay in conversion of many of these facilities to civilian uses. Over the last 10 years problems related to hazardous waste remediation have emerged as a high national and international priority.

Topics: Hazardous waste (60%) more

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Journal ArticleDOI
Ryoji Asahi1, Takeshi Morikawa1, T. Ohwaki1, Koyu Aoki1, Y. Taga1 
13 Jul 2001-Science
TL;DR: Film and powders of TiO2-x Nx have revealed an improvement over titanium dioxide (TiO2) under visible light in optical absorption and photocatalytic activity such as photodegradations of methylene blue and gaseous acetaldehyde and hydrophilicity of the film surface.
Abstract: To use solar irradiation or interior lighting efficiently, we sought a photocatalyst with high reactivity under visible light. Films and powders of TiO 2- x N x have revealed an improvement over titanium dioxide (TiO 2 ) under visible light (wavelength 2 has proven to be indispensable for band-gap narrowing and photocatalytic activity, as assessed by first-principles calculations and x-ray photoemission spectroscopy.

10,756 citations

Journal ArticleDOI
Ulrike Diebold1
Abstract: Titanium dioxide is the most investigated single-crystalline system in the surface science of metal oxides, and the literature on rutile (1 1 0), (1 0 0), (0 0 1), and anatase surfaces is reviewed This paper starts with a summary of the wide variety of technical fields where TiO 2 is of importance The bulk structure and bulk defects (as far as relevant to the surface properties) are briefly reviewed Rules to predict stable oxide surfaces are exemplified on rutile (1 1 0) The surface structure of rutile (1 1 0) is discussed in some detail Theoretically predicted and experimentally determined relaxations of surface geometries are compared, and defects (step edge orientations, point and line defects, impurities, surface manifestations of crystallographic shear planes—CSPs) are discussed, as well as the image contrast in scanning tunneling microscopy (STM) The controversy about the correct model for the (1×2) reconstruction appears to be settled Different surface preparation methods, such as reoxidation of reduced crystals, can cause a drastic effect on surface geometries and morphology, and recommendations for preparing different TiO 2 (1 1 0) surfaces are given The structure of the TiO 2 (1 0 0)-(1×1) surface is discussed and the proposed models for the (1×3) reconstruction are critically reviewed Very recent results on anatase (1 0 0) and (1 0 1) surfaces are included The electronic structure of stoichiometric TiO 2 surfaces is now well understood Surface defects can be detected with a variety of surface spectroscopies The vibrational structure is dominated by strong Fuchs–Kliewer phonons, and high-resolution electron energy loss spectra often need to be deconvoluted in order to render useful information about adsorbed molecules The growth of metals (Li, Na, K, Cs, Ca, Al, Ti, V, Nb, Cr, Mo, Mn, Fe, Co, Rh, Ir, Ni, Pd, Pt, Cu, Ag, Au) as well as some metal oxides on TiO 2 is reviewed The tendency to ‘wet’ the overlayer, the growth morphology, the epitaxial relationship, and the strength of the interfacial oxidation/reduction reaction all follow clear trends across the periodic table, with the reactivity of the overlayer metal towards oxygen being the most decisive factor Alkali atoms form ordered superstructures at low coverages Recent progress in understanding the surface structure of metals in the ‘strong-metal support interaction’ (SMSI) state is summarized Literature is reviewed on the adsorption and reaction of a wide variety of inorganic molecules (H 2 , O 2 , H 2 O, CO, CO 2 , N 2 , NH 3 , NO x , sulfur- and halogen-containing molecules, rare gases) as well as organic molecules (carboxylic acids, alcohols, aldehydes and ketones, alkynes, pyridine and its derivates, silanes, methyl halides) The application of TiO 2 -based systems in photo-active devices is discussed, and the results on UHV-based photocatalytic studies are summarized The review ends with a brief conclusion and outlook of TiO 2 -based surface science for the future

6,656 citations

Journal ArticleDOI
Abstract: Scientific studies on photocatalysis started about two and a half decades ago. Titanium dioxide (TiO 2 ), which is one of the most basic materials in our daily life, has emerged as an excellent photocatalyst material for environmental purification. In this review, current progress in the area of TiO 2 photocatalysis, mainly photocatalytic air purification, sterilization and cancer therapy are discussed together with some fundamental aspects. A novel photoinduced superhydrophilic phenomenon involving TiO 2 and its applications are presented.

6,367 citations

Cites background from "Environmental Applications of Semic..."

  • ...Their prediction has indeed been borne out, as evidenced by the extensive global efforts in this area [4–11,15,16,19–42]....


01 Jan 2008
Abstract: Abstract Scientific studies on photocatalysis started about two and a half decades ago. Titanium dioxide (TiO 2 ), which is one of the most basic materials in our daily life, has emerged as an excellent photocatalyst material for environmental purification. In this review, current progress in the area of TiO 2 photocatalysis, mainly photocatalytic air purification, sterilization and cancer therapy are discussed together with some fundamental aspects. A novel photoinduced superhydrophilic phenomenon involving TiO 2 and its applications are presented.

6,294 citations

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01 Jan 1993
Abstract: Preface. Part I: Introduction. 1. General Topic and Overview. 2. An Introduction to Environmental Organic Chemicals. Part II: Equilibrium Partitioning Between Gaseous, Liquid, and Solid Phases. 3. Partitioning: Molecular Interactions and Thermodynamics. 4. Vapor Pressure. 5. Activity Coefficient and Solubility in Water. 6. Air-Organic Solvent and Air-Water Partitioning. 7. Organic Liquid-Water Partitioning. 8. Organic Acids and Bases: Acidity Constant and Partitioning Behavior. 9. Sorption I: General Introduction and Sorption Processes Involving Organic Matter. 10. Sorption II: Partitioning to Living Media - Bioaccumulation and Baseline Toxicity. 11. Sorption III: Sorption Processes Involving Inorganic Surfaces. Part III: Transformation Processes. 12. Thermodynamics and Kinetics of Transformation Reactions. 13. Chemical Transformations I: Hydrolysis and Reactions Involving Other Nucleophilic Species. 14. Chemical Transformations II: Redox Reactions. 15. Direct Photolysis. 16. Indirect Photolysis: Reactions with Photooxidants in Natural Waters and in the Atmosphere. 17. Biological Transformations. Part IV: Modeling Tools: Transport and Reaction. 18. Transport by Random Motion. 19. Transport Through Boundaries. 20. Air-Water Exchange. 21. Box Models. 22. Models in Space and Time. Part V: Environmental Systems and Case Studies. 23. Ponds, Lakes, and Oceans. 24. Rivers. 25. Groundwater. Appendix. Bibliography. Index (Subject Index, Compound Index, List of Illustrative Examples).

4,332 citations

01 Jan 1992

1,911 citations

01 Oct 1989
Abstract: The book is devoted to the study of photocatalysis, a very popular area of modern-day chemistry. The various chapters will cover aspects of the field that are of particular interest to those at the top in research expertise. Among the subjects discussed are: the theory and preparation of semiconductor mate- rials, the various types of heterogeneous photocatalysis methods, absorption and desorption in photocatalysis, and applied photoca- talysis in energy production. A knowledge of photochemistry is not essential as the format and selection of topics make the field evolve naturally. The student is first introduced to the meaning of photocatalysis and subsequently taken through the essentials of photochemistry towards bridging it to semiconductor materials. The reader is also introduced to the colloidal state of semiconductors followed by thermodynamic and kinetic aspects of photocatalysis. The book is aimed at professional, faculty and graduate students in inorganic and physical chemistry, organic chemistry, oganometallic chemistry, and catalysis.

1,655 citations

30 Nov 1980
Abstract: 1. The Solid and the Solution.- 1.1. The Solid.- 1.1.1. Donors, Acceptors, and Traps.- 1.1.2. Energy Levels at the Surface.- 1.1.3. Conductance in Solids.- 1.2. The Solution.- 1.2.1. Introduction.- 1.2.2. The Electrode Fermi Energy as a Function of the Redox Couples in Solution.- 1.2.3. The Relation between the Hydrogen and the Vacuum Scales of Energy.- 1.2.4. Fluctuating Energy Levels in Solution.- 1.2.5. The Energy Levels Associated with Two-Equivalent Ions.- 1.2.6. Conductance in Liquids.- 2. The Solid/Liquid Interface.- 2.1. Surface Ions and Their Energy Levels.- 2.1.1. Adsorption.- 2.1.2. Surface States at the Solid/Liquid Interface.- 2.2. Double Layers at the Solid/Liquid Interface.- 2.2.1. General.- 2.2.2. The Gouy Layer.- 2.2.3. The Helmholtz Double Layer.- 2.2.4. The Space Charge Double Layer in the Semiconductor.- 2.3. Theoretical Predictions of the Energy Levels of Band Edges.- 2.4. The Band Model of the Solid/Solution Interface.- 3. Theory of Electron and Hole Transfer.- 3.1. Introduction.- 3.1.1. General.- 3.1.2. The Activation Energy in Electrode Reactions.- 3.2. Classical Model.- 3.3. The Energy Level Model of Charge Transfer.- 3.3.1. General.- 3.3.2. The Metal Electrode.- 3.3.3. The Semiconductor Electrode.- 3.4. Qualitative Description of Electrode Processes Using the Band Model.- 3.4.1. The Behavior of the Metal Electrode.- 3.4.2. The Behavior of the Semiconductor Electrode.- 3.4.3. The Transition between Semiconductor and Metallic Behavior.- 4. Measurement Techniques.- 4.1. Capacity Measurements.- 4.1.1. Introduction.- 4.1.2. Measurement Theory.- 4.1.3. Analysis.- 4.1.4. Complex Mott-Schottky Plots.- 4.1.5. Determination of Band Edges.- 4.2. Measurements of the Current/Voltage Characteristics.- 4.2.1. General Techniques Voltammetry.- 4.2.2. Rotating Electrodes.- 4.2.3. Illumination.- 4.3. Other Techniques.- 4.3.1. Techniques for Vs Measurement.- 4.3.2. Techniques to Determine Surface Species or Phases.- 4.3.3. Techniques to Study Electrode Reactions.- 5. The Properties of the Electrode and Their Effect on Electrochemical Measurements.- 5.1. The Behavior of the Perfect Crystal.- 5.1.1. The Helmholtz Double Layer: The Surface Charges on the Electrode.- 5.1.2. The Space Charge Region of the Perfect Crystal.- 5.2. The Behavior of Electrode Defects.- 5.2.1. Introduction.- 5.2.2. Deviations of Mott-Schottky Plots Due to Bulk Flaws.- 5.2.3. Current Flow Associated with Bulk Flaws.- 5.3. Observed Flat Band Potentials for Various Semiconductors.- 6. Observations of Charge Transfer at an Inert Semiconductor Electrode.- 6.1. Introduction.- 6.2. Majority Carrier Capture.- 6.2.1. Direct Carrier Transfer to Ions in Solution.- 6.2.2. Indirect Electron Transfer to Ions in Solution.- 6.3. Minority Carrier Capture.- 6.3.1. Minority Carrier Capture on Two-Equivalent Species: Radical Formation and Current Doubling.- 6.3.2. Minority Carrier Capture by One-Equivalent Ions.- 6.3.3. Photocatalysis.- 6.4. Intrinsic Surface States and Recombination Centers.- 6.4.1. Intrinsic Surface States as Carrier Transfer Centers.- 6.4.2. Intrinsic Surface States and Ions in Solution as Recombination Centers.- 6.5. Carrier Injection.- 6.5.1. Direct Electron and Hole Injection.- 6.5.2. Injection by Tunneling.- 6.5.3. Injection by Optically Excited Ions: Dye Injection.- 6.6. High-Current, High-Voltage Processes.- 6.6.1. Introduction.- 6.6.2. High Currents with Accumulation Layers.- 6.6.3. Tunneling and Breakdown on Non-Transition-Metal Semiconductors.- 6.6.4. Practical Electrodes.- 6.7. Analysis of Complicated Electrode Reactions using the Tools of Semiconductor Electrochemistry.- 6.7.1. The Photocatalytic Oxidation of Formic Acid.- 6.7.2. Analysis of the Energy Levels of Two-Equivalent Species.- 6.7.3. The Reduction of Iodine on CdS.- 7. Chemical Transformation in the Electrode Reaction.- 7.1. Introduction.- 7.2. Inner Sphere Changes during Redox Reactions at an Inert Electrode.- 7.3. Adsorption onto and Absorption into the Electrode.- 7.3.1. Adsorption of Water, Hydrogen, and Oxygen.- 7.3.2. Adsorption of Electrolyte Ions.- 7.3.3. Action of Deposited Species.- 7.3.4. Movement of Impurities and Defects into the Electrode.- 7.4. Corrosion.- 7.4.1. Introduction.- 7.4.2. Theory and Observations of Semiconductor Corrosion.- 7.4.3. Stabilizing Agents to Prevent Corrosion.- 8. Coated Electrodes.- 8.1. Introduction.- 8.1.1. The Band Model for Oxide Films.- 8.1.2. Thin Films.- 8.1.3. The Structure of Thick Films.- 8.2. Current Transport through Oxide Films.- 8.2.1. Thin Oxide Layers.- 8.2.2. Model of Electronic Conduction through Thick Coherent Layers.- 8.2.3. Semiconducting Oxide Layers on Metal Electrodes.- 8.2.4. Insulating Layers on Metal and Semiconductor Electrodes.- 8.3. Deposition of Reaction Products on Semiconductor Electrodes.- 9. Applications of Semiconductor Electrodes.- 9.1. Solar Energy Conversion.- 9.1.1. Introduction.- 9.1.2. Photovoltaic Cells.- 9.1.3. Conversion of Optical to Chemical Energy.- 9.1.4. Corrosion of PEC Cells.- 9.1.5. The Future Potential of PEC Solar Cells.- 9.2. Electrocatalysis on Semiconductors.- 9.2.1. General.- 9.2.2. Surface State Additives and Narrow Bands in Electrocatalysis.- 9.3. New Devices.- 9.4. Electropolishing of Semiconductors.- References.- References to Review Articles and Books.- Author Index.

1,245 citations