Interface and surface analysis of Ru/CdS
01 Jan 1996-Journal of Materials Science Letters (Kluwer Academic Publishers)-Vol. 15, Iss: 21, pp 1921-1923
About: This article is published in Journal of Materials Science Letters.The article was published on 1996-01-01. It has received 4 citations till now.
Citations
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TL;DR: For a variety of metals and semiconductors, an attempt is made to generalize observations in the literature on the effect of process conditions applied during photodeposition on (i) particle size distributions, (ii) oxidation states of the metals obtained, and (iii) consequences for photocatalytic activities.
Abstract: In this review, for a variety of metals and semiconductors, an attempt is made to generalize observations in the literature on the effect of process conditions applied during photodeposition on (i) particle size distributions, (ii) oxidation states of the metals obtained, and (iii) consequences for photocatalytic activities. Process parameters include presence or absence of (organic) sacrificial agents, applied pH, presence or absence of an air/inert atmosphere, metal precursor type and concentration, and temperature. Most intensively reviewed are studies concerning (i) TiO2; (ii) ZnO, focusing on Ag deposition; (iii) WO3, with a strong emphasis on the photodeposition of Pt; and (iv) CdS, again with a focus on deposition of Pt. Furthermore, a detailed overview is given of achievements in structure-directed photodeposition, which could ultimately be employed to obtain highly effective photocatalytic materials. Finally, we provide suggestions for improvements in description of the photodeposition methods applied when included in scientific papers.
446 citations
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TL;DR: It is demonstrated further that a fine control of the metal Ru nanoparticle size on the TiO2 support was possible via a controlled nanocluster growth under irradiation, while the nanoparticles revealed a good resistance to thermal sintering.
Abstract: Ru/TiO₂ are promising heterogeneous catalysts in different key-reactions taking place in the catalytic conversion of biomass towards fuel additives, biofuels, or biochemicals. TiO₂ supported highly dispersed nanometric-size metallic Ru catalysts were prepared at room temperature via a solar light induced photon-assisted one-step synthesis in liquid phase, far smaller Ru nanoparticles with sharper size distribution being synthesized when compared to the catalysts that were prepared by impregnation with thermal reduction in hydrogen. The underlying strategy is based on the redox photoactivity of the TiO₂ semi-conductor support under solar light for allowing the reduction of metal ions pre-adsorbed at the host surface by photogenerated electrons from the conduction band of the semi-conductor in order to get a fine control in terms of size distribution and dispersion, with no need of chemical reductant, final thermal treatment, or external hydrogen. Whether acetylacetonate or chloride was used as precursor, 0.6 nm sub-nanometric metallic Ru particles were synthesized on TiO₂ with a sharp size distribution at a low loading of 0.5 wt.%. Using the chloride precursor was necessary for preparing Ru/TiO₂ catalysts with a 0.8 nm sub-nanometric mean particle size at 5 wt.% loading, achieved in basic conditions for benefitting from the enhanced adsorption between the positively-charged chloro-complexes and the negatively-charged TiO₂ surface. Remarkably, within the 0.5⁻5 wt.% range, the Ru content had only a slight influence on the sub-nanometric particle size distribution, thanks to the implementation of suitable photo-assisted synthesis conditions. We demonstrated further that a fine control of the metal Ru nanoparticle size on the TiO₂ support was possible via a controlled nanocluster growth under irradiation, while the nanoparticles revealed a good resistance to thermal sintering.
7 citations
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TL;DR: In this article, the changes in RuCl 3 formation and surface roughness with various cleaning processes were investigated and it was confirmed that, during Cl 2 dry etching to remove the absorber layer, RuCl3 was formed on the Ru capping layer surface, and the surface roughs thereby deteriorated.
Abstract: Ru-capped extreme ultraviolet lithography photomasks require cleaning after patterning of the absorber layer. In this study, it was confirmed that, during Cl 2 dry etching to remove the absorber layer, RuCl 3 was formed on the Ru capping layer surface, and the surface roughness thereby deteriorated. Therefore, the changes in RuCl 3 formation and surface roughness with various cleaning processes were investigated. Among the treatments used, i . e ., sulfuric peroxide mixture, an ammonia peroxide mixture or ozonated water (DIO 3 ), DIO 3 exhibited the most effective Cl removal efficiency and surface roughness recovery. DIO 3 treatment successfully reduced the Cl-terminated Ru surface to its original state and decreased the surface roughness to the pre-Cl 2 -etched Ru value.
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TL;DR: In this paper, the effect of the variation of the incident irradiance and photodeposition rate on the photocatalytic properties of ruthenium nanoparticles supported on TiO2 was evaluated by using the degradation of formic acid in water under UV-A light.
Abstract: Photoassisted synthesis is as a highly appealing green procedure for controlled decoration of semiconductor catalysts with co-catalyst nanoparticles, which can be carried out without the concourse of elevated temperatures, external chemical reducing agents or applied bias potential and in a simple slurry reactor. The aim of this study is to evaluate the control that such a photoassisted method can exert on the properties of ruthenium nanoparticles supported on TiO2 by means of the variation of the incident irradiance and hence of the photodeposition rate. For that purpose, different Ru/TiO2 systems with the same metal load have been prepared under varying irradiance and characterized by means of elemental analysis, transmission electron microscopy and X-ray photoelectron spectroscopy. The photocatalytic activity of the so-obtained materials has been evaluated by using the degradation of formic acid in water under UV-A light. Particles with size around or below one nanometer were obtained, depending on the irradiance employed in the synthesis, with narrow size distribution and homogeneous dispersion over the titania support. The relation between neutral and positive oxidation states of ruthenium could also be controlled by the variation of the irradiance. The obtained photocatalytic activities for formic acid oxidation were in all cases higher than that of undecorated titania, with the sample obtained with the lowest irradiation giving rise to the highest oxidation rate. According to the catalysts characterization, photocatalytic activity is influenced by both Ru size and Ru0/Ruδ+ ratio.
References
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TL;DR: In this article, the x-ray emission wavelengths have been reevaluated and placed on a consistent \AA{}* scale, which makes "best" use of all xray wavelength data, and also permits calculation of the probable error for each energy difference.
Abstract: All of the x-ray emission wavelengths have recently been reevaluated and placed on a consistent \AA{}* scale. For most elements these data give a highly overdetermined set of equations for energy level differences, which have been solved by least-squares adjustment for each case. This procedure makes "best" use of all x-ray wavelength data, and also permits calculation of the probable error for each energy difference. Photoelectron measurements of absolute energy levels are more precise than x-ray absorption edge data. These have been used to establish the absolute scale for eighty-one elements and, in many cases, to provide additional energy level difference data. The x-ray absorption wavelengths were used for eight elements and ionization measurements for two; the remaining five were interpolated by a Moseley diagram involving the output values of energy levels from adjacent elements. Probable errors are listed on an absolute energy basis. In the original source of the present data, a table of energy levels in Rydberg units is given. Difference tables in volts, Rydbergs, and milli-\AA{}* wavelength units, with the respective probable errors, are also included there.
1,547 citations
Book•
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22 Dec 2012
TL;DR: In this paper, the authors present a review of the literature on electron spectroscopy and its application in the field of computer vision. But they do not discuss the specific applications of electron spectrograms.
Abstract: 1 Introduction.- 1. History.- 2. Scope of Present Book and Review of Past Books.- 3. Name-Calling.- 4. Areas Related to Electron Spectroscopy Not to be Discussed in Detail.- 4.1. Electron-Impact Spectroscopy.- 4.2. Photoemission.- 4.3. Penning Ionization Spectroscopy.- 4.4. Ion Neutralization Spectroscopy.- 5. Fields Related to Electron Spectroscopy.- 2 Instrumentation and Experimental Procedures.- 1. Source Volume.- 1.1. Excitation Devices.- 1.1.1. Electron Gun.- 1.1.2. X-Ray Tube.- 1.1.3. Synchrotron Radiation.- 1.1.4. Vacuum-UV Sources.- 1.2. Target Sample.- 1.2.1. Gases.- 1.2.2. Solids.- 1.2.3. Condensed Vapors, Liquids, and Targets at Other Than Room Temperature.- 1.3. Chamber for Angular Distribution Studies.- 1.4. Preacceleration and Deceleration.- 2. Analyzer.- 2.1. Cancellation of Magnetic Fields.- 2.1.1. Helmholtz Coils.- 2.1.2. Magnetic Shielding.- 2.2. Types of Analyzers.- 2.2.1. Retarding Grid.- 2.2.2. Dispersion.- 3. Detector Systems and Data Analysis.- 3.1. Single-Channel Detector.- 3.2. Position-Sensitive Detector.- 3.3. Scanning the Spectrum.- 3.4. Data Analysis.- 4. New Developments.- 5. Review of Commercial Instruments.- 5.1. AEI.- 5.2. Du Pont.- 5.3. Hewlett-Packard.- 5.4. McPherson.- 5.5. Perkin-Elmer.- 5.6. Physical Electronics.- 5.7. McCrone-RCI.- 5.8. Vacuum Generators, Inc..- 5.9. Varian.- 5.10. Others.- 3 Fundamental Concepts.- 1. Photoelectric Effect.- 2. Binding Energy.- 3. Final States and the Sudden Approximation.- 3.1. Spin-Orbit Splitting.- 3.2. Multiplet Splitting.- 3.3. Jahn-Teller Splitting.- 3.4. Electron Shakeoff and Shakeup.- 3.5. Configuration Interaction.- 3.6. Koopmans' Theorem and the Sudden Approximation.- 3.7. Vibrational and Rotational Final States.- 4. Atomic Wave Functions.- 5. Molecular Orbital Theory.- 5.1. Theoretical Models.- 5.1.1. Ab Initio Calculations.- 5.1.2. Semiempirical Calculations.- 5.2. Basis Set Extension and MO Mixing.- 5.3. Atomic and Molecular Orbital Nomenclature.- 5.3.1. Atoms.- 5.3.2. Molecules.- 4 Photoelectron Spectroscopy of the Outer Shells.- 1. Introduction.- 2. Energy Level Scheme.- 2.1. Binding Energy.- 2.2. Final States.- 2.2.1. Spin-Orbit Splitting.- 2.2.2. Multiplet Splitting due to Spin Coupling.- 2.2.3. Jahn-Teller Effect.- 2.2.4. Electron Shakeoff and Shakeup.- 2.2.5. Configuration Interaction.- 2.2.6. Resonance Absorption.- 2.2.7. Collision Peaks.- 3. Identification of the Orbital.- 3.1. Ionization Potentials.- 3.1.1. Characteristic Ionization Bands.- 3.1.2. Effects of Substituents.- 3.1.3. Sum Rule.- 3.1.4. The Perfluoro Effect.- 3.1.5. Dependence on Steric Effects.- 3.2. Identification of Orbitals by Vibrational Structure.- 3.3. Identification of Molecular Orbitals from Intensities of Ionization Bands.- 3.4. Identification of Molecular Orbitals by Angular Distribution.- 4. Comparison of PESOS with Other Experimental Data.- 4.1. Optical Spectroscopy.- 4.2. Mass Spectroscopy.- 5. Survey of the Literature on PESOS.- 5.1. Atoms.- 5.2. Diatomic Molecules.- 5.2.1. H2.- 5.2.2. N2 and CO.- 5.2.3. O2 and NO.- 5.2.4. Diatomic Molecules Containing Halogen.- 5.3. Triatomic Molecules.- 5.3.1. Linear Triatomic Molecules.- 5.3.2. Bent Triatomic Molecules.- 5.4. Organic Molecules.- 5.4.1. Methane, Alkanes, and Tetrahedral Symmetry.- 5.4.2. Unsaturated Aliphatics.- 5.4.3. Ring Compounds.- 5.4.4. Multiring Compounds.- 5.4.5. Organic Halides.- 5.4.6. Miscellaneous Organic Compounds Containing Oxygen, Nitrogen, Sulfur, and Phosphorus.- 5.5. Organometallics and Miscellaneous Inorganic Polyatomic Molecules.- 5.6. Ions, Transient Species, and Other Special Studies in PESOS.- 6. Studies on Solids.- 7. Analytical Applications of PESOS.- 5 Photoelectron Spectroscopy of the Inner Shells.- 1. Atomic Structure.- 2. Theoretical Basis of Chemical Shifts of Core Electrons.- 2.1. Valence Shell Potential Model.- 2.2. Effect of Neighboring Atoms.- 2.3. Calculation of Net Charge from Electronegativity.- 2.4. Calculation of Net Charge from Semiempirical MO.- 2.5. Use of Ab Initio Calculations for Chemical Shifts.- 2.6. Correlation of Chemical Shift with Thermochemical Data.- 3. Summary of Data on Chemical Shifts as a Function of the Periodic Table.- 3.1. Carbon.- 3.2. Nitrogen and Phosphorus.- 3.3. Sulfur and Oxygen.- 3.4. Group IIIA, IVA, VA, and VIA Elements.- 3.4.1. Group IIIA: B, Al, Ga, In, and Tl.- 3.4.2. Group IVA: C, Si, Ge, Sn, and Pb.- 3.4.3. Group VA: N, P, As, Sb, and Bi.- 3.4.4. Group VIA: O, S, Se, and Te.- 3.5. Halides and Rare Gases.- 3.6. Alkali Metals and Alkaline Earths.- 3.7. Transition Metals.- 3.7.1. First Transition Metal Series: Sc, Ti, V, Cr, Mn, Fe, Co, Ni.- 3.7.2. Second Transition Metal Series: Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd.- 3.7.3. Third Transition Metal Series: Hf, Ta, W, Re, Os, Ir, Pt.- 3.8. Groups IB and IIB: Cu, Ag, Au, Zn, Cd, Hg.- 3.9. Rare Earths and Actinides.- 4. Special Topics on Shifts in Core Binding Energies.- 4.1. Experimental and Interpretive Problems in PESIS.- 4.1.1. Comparative Problems in the Gas and Solid Phases.- 4.1.2. Charging.- 4.1.3. Definition of Binding Energy for Insulators.- 4.1.4. Binding Energy of Surface Atoms.- 4.1.5. Radiation Effects.- 4.1.6. Linewidths.- 4.2. Inorganic Compounds.- 4.2.1. Multiple Chemical Environment.- 4.2.2. Coordination Complexes.- 4.3. Organic Compounds.- 4.3.1. Resonance.- 4.3.2. Substituent Effects.- 4.3.3. Group Analysis.- 4.3.4. Specific Studies on Organic Molecules.- 4.4. Comparison of Core Electron Binding Energy Shifts with Other Physical Quantities.- 4.4.1. Mossbauer Isomer Shift.- 4.4.2. NMR.- 4.4.3. Other Physical Data.- 5. Other Applications of PESIS.- 5.1. Multicomponent Structure.- 5.1.1. Multiplet or Exchange Splitting.- 5.1.2. Electron Shakeoff and Shakeup.- 5.1.3. Configuration Interaction.- 5.1.4. Characteristic Energy Losses.- 5.1.5. Determining the Nature of Multicomponent Structure.- 5.2. PESIS for Surface Studies.- 5.3. Angular Studies with PESIS.- 6. Use of PESIS for Applied Research.- 6.1. PESIS as an Analytical Tool.- 6.2. Biological Systems.- 6.3. Geology.- 6.4. Environmental Studies.- 6.5. Surface Studies.- 6.6. Polymers and Alloys.- 6.7. Radiation Studies.- 6.8. Industrial Uses.- 6 Auger Electron Spectroscopy.- 1. Theory of the Auger Process.- 2. Comparison of the Auger Phenomenon with the Photoelectric Effect and X-Ray Emission.- 3. Use of Auger Spectroscopy for Gases.- 3.1. Atoms.- 3.2. Molecules.- 3.3. Study of Ionization Phenomena by Auger Spectroscopy.- 3.4. Autoionization.- 3.5. Auger Spectroscopy for Use in Gas Analysis.- 4. Use of Auger Spectroscopy in the Study of Solids.- 4.1. Special Problems Encountered on Using AES with Solids.- 4.1.1. Variables Concerned with Production of Auger Electrons.- 4.1.2. High-Energy Satellite Lines.- 4.1.3. Characteristic Energy Losses.- 4.1.4. Charging in Nonconducting Samples.- 4.2. High-Resolution Auger Spectroscopy with Solids.- 4.3. General Analytical Use of Auger Spectroscopy.- 4.4. Use of Auger Spectroscopy in the Study of Surfaces.- 4.4.1. General Considerations.- 4.4.2. Literature Survey of Surface Applications.- 4.5. Other Methods for Surface Analysis.- 4.5.1. Comparison of PESIS and Auger Spectroscopy for Surface Studies.- 4.5.2. Methods of Surface Analysis Other than AES and PESIS.- Appendixes.- 1. Atomic Binding Energies for Each Subshell for Elements Z = 1-106.- 3. Compilation of Data on Shifts in Core Binding Energies.- 4. Acronyms and Definitions of Special Interest in Electron Spectroscopy.- References.
651 citations
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TL;DR: In this article, a bifunctional redox catalyst composed of RuO2 and Pt co-supported on colloidal TiO2 particles is used for water decomposition by visible light illumination.
Abstract: A bifunctional redox catalyst, composed of Pt and RuO2 co-deposited on a colloidal TiO2 carrier, is a highly potent mediator for water decomposition by visible light1. The system contains apart from the sensitizer (Ru(bipy)2+3) an electron relay—methylviologen. The latter is reduced on light excitation, and the photoreaction is coupled with catalytic steps2 generating H2 and O2 from water. To rationalize the surprisingly high efficiency of this photoredox system, we proposed a mechanism involving species adsorbed at the TiO2 surface. This led us to explore sensitizers which through suitable functionalization show an enhanced affinity for adsorption at the particle–water interface. We describe here the performance of electron relay-free systems capable of efficiently decomposing water into H2 and O2 under visible light illumination. A bifunctional redox catalyst composed of RuO2 and Pt co-supported on colloidal TiO2 particles is used. The only other component present is a sensitizer. Amphiphilic surfactant derivatives of Ru(bipy)2+3 exhibit extremely high activity in promoting the water cleavage process. Adsorption of the sensitizer at the TiO2 particle–water interface and electron ejection into the TiO2 conduction band are evoked to explain the observations. Exposure to UV radiation leads to efficient water cleavage in the absence of sensitizer.
334 citations
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TL;DR: In this article, a reaction path for evolution and corrosion on Ru and anodes is proposed, where the surface of anodes prepared by thermal decomposition of contains some, which is stable during anodic polarization.
Abstract: Anodic oxidation of Ru and electrodes in has been investigated using x‐ray photoelectron spectroscopy. During evolution on Ru a highly defective hydrated oxide film is formed as a result of corrosion. At a temperature of 310°C in vacuum this film decomposes to metallic ruthenium. The surface of anodes prepared by thermal decomposition of contains some , which is stable during anodic polarization. A reaction path for evolution and corrosion on Ru and anodes is proposed.
281 citations
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TL;DR: In this article, aqueous CdS dispersions loaded with Pt and RuO2 by visible light produces hydrogen and oxygen in stoichiometric proportion, and no degradation of the photocatalyst is noted after 60 h of irradiation time.
Abstract: Illumination of aqueous CdS dispersions loaded with Pt and RuO2 by visible light produces hydrogen and oxygen in stoichiometric proportion. No degradation of the photocatalyst is noted after 60 h of irradiation time. The RuO2 deposit on the particle surface greatly accelerates the transfer of holes from the semiconductor valence band to the aqueous solution thus inhibiting photocorrosion.
163 citations