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282 Appendix D. Site Reports—Japan results using different synthesis techniques and parametric studies to optimize the catalyst fabrication, and (d) the wt% of Au loading. The characteristic nature of the gold catalyst was the main topic of the science presentations from Dr. Haruta and members of his staff. This included evidence for the structure-sensitive character of the gold catalysts, namely, the strong dependence on particle size, type of support material, and the interface structure of the Au catalyst with the support. Gold catalysts have unique behavior, being active at low temperature. For example, CO oxidation occurs on nanoscale gold catalysts at temperatures as low as -70°C. In addition, the gold catalysts are found to exhibit very high selectivity for partial oxidation reactions, such as oxidation of propylene to propylene oxide with 100% selectivity at 50°C as well as near room temperature reduction of nitric oxide. A key scientific finding is the sensitive role that H 2 O plays in activating the gold catalytic behavior. Similar results with Pd and Pt catalysts show effectively no propylene oxide yield, but give about 100% conversion to propane. The fundamental work on gold catalysts has led to “odor eaters” for the bathroom, a recent commercialization. In addition to the ongoing studies on gold catalysts, there is a significant effort to apply the learning from the gold system to other catalyst systems, using, for example, Pt- or Pd-based catalysts with the expectation that particle size effects will lead to novel materials with highly specific functionality. In addition to the catalysis work, the Basic Research Section also has efforts in developing optical gas sensors, and in studies of the unusual nonlinear optical properties of gold nanoparticles. The use of sputtered gold or nanoparticle gold colloids deposited on transition metal oxide surfaces has produced surfaces for which selective adsorption of H 2 and CO gases can be detected. The use of entirely optical techniques for selective detection of H 2 was being promoted, since such detection would eliminate the possibility of fire ignition or explosion in H 2 atmospheres. Dr. Ando summarized the optical gas sensor work as follows: • Au nanoparticles on nickel oxide show enhanced selectively to both CO and H 2 • Au nanoparticles on copper oxide show large selectivity and sensitivity to CO • Au nanoparticles on cobalt oxide show two effects: – Enhanced selectivity to H 2 at the plasmon band of Au – Decreased absorbance (selectivity) to both CO and H 2 away from the Au plasmon center frequency. The results open the possibility for strictly optical recognition of H 2 and CO.
Appendix D. Site Reports—Japan 283 Dr. Fukumi showed that nanoscale gold colloids dispersed in glasses exhibit novel nonlinear optical properties. The materials are produced by ion implantation of Au + into silica glass. The Au+ ion energy is 1.5 MeV with densities of 10 16 -10 17 Au + ions/cm 2 . Characterization by TEM showed the average particle size was 8.6 nm diameter. In these materials, the third order nonlinear susceptibility χ 3 was measured to be 1.2 x 10 -7 esu, about four orders of magnitude higher than that obtained by a melting method used by others to produce the gold/glass system. Following the technical presentations, the WTEC team enjoyed a lunch that Dr. Haruta had kindly arranged with the Director General of ONRI, Dr. Teruo Kodama, and Dr. Noboru Wakabayashi, the senior officer for research planning. After lunch the team had a tour of the lab facilities of the Interdisciplinary Basic Research Section. From these interactions we learned that funding for the National Laboratory at Osaka increased by 16% in 1996, but simultaneously, the permanent staff is decreasing. The decrease in permanent staff is somewhat compensated by the increase in (mostly) foreign postdoctoral support to the 30-40 person level. The lab facilities for the Basic Science Section are impressive, consisting of several catalyst testing units and a special testing unit with all stainless steel surfaces that have been chromium oxide-coated to allow water vapor levels to be reduced to < 10 ppb. This is the only unit in the world with this capability, which has allowed this group to carefully isolate the role of water vapor in the catalytic reactions. Recent funding has allowed purchase of a new high resolution TEM (~$1.3 million), and a new sophisticated surface science apparatus (>$1 million) which at the time of the WTEC visit had been ordered but not yet delivered. The new equipment is to be used to better understand the differences and similarities of surface reactions occurring at low pressure under UHV conditions and those occurring in the higher pressure catalytic reactions carried out under actual processing conditions.
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National Science and Technology Cou
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WTEC Panel on NANOSTRUCTURE SCIENCE
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ABSTRACT This report reviews the st
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Foreword Timely information on scie
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Foreword iii collaboration and thus
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Contents Foreword Table of Contents
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List of Figures 1.1 Organization of
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List of Figures ix 5.12 Granular GM
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List of Tables ES.1 Technological I
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Executive Summary Richard W. Siegel
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Executive Summary xix past decade,
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Executive Summary xxi TABLE ES.2. C
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Executive Summary xxiii blocks, and
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Chapter 1 Introduction and Overview
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1. Introduction and Overview 3 •
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1. Introduction and Overview 5 worl
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1. Introduction and Overview 7 grow
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1. Introduction and Overview 9 lead
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1. Introduction and Overview 11 2.
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1. Introduction and Overview 13 It
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Chapter 2 Synthesis and Assembly Ev
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2. Synthesis and Assembly 17 transi
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2. Synthesis and Assembly 19 probe
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2. Synthesis and Assembly 21 by adj
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2. Synthesis and Assembly 23 blocks
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2. Synthesis and Assembly 25 Self-A
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2. Synthesis and Assembly 27 Figure
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2. Synthesis and Assembly 29 us to
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2. Synthesis and Assembly 31 Brotzm
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2. Synthesis and Assembly 33 Siegel
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Chapter 3 Dispersions and Coatings
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3. Dispersions and Coatings 37 exis
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3. Dispersions and Coatings 39 more
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3. Dispersions and Coatings 41 into
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3. Dispersions and Coatings 43 of N
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3. Dispersions and Coatings 45 oppo
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3. Dispersions and Coatings 47 Kanz
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Chapter 4 High Surface Area Materia
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4. High Surface Area Materials 51 w
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4. High Surface Area Materials 53 F
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4. High Surface Area Materials 55 T
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4. High Surface Area Materials 57 s
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4. High Surface Area Materials 59 T
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4. High Surface Area Materials 61 F
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4. High Surface Area Materials 63 m
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4. High Surface Area Materials 65 I
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Chapter 5 Functional Nanoscale Devi
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5. Functional Nanoscale Devices 69
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Chapter 6 Bulk Behavior of Nanostru
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6. Bulk Behavior of Nanostructured
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Chapter 7 Biologically Related Aspe
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7. Biologically Related Aspects of
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Chapter 8 Research Programs on Nano
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8. Research Programs on Nanotechnol
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APPENDICES Appendix A. Biographies
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Appendix A. Biographies of Panelist
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Appendix B. Site Reports—Europe S
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Appendix B. Site Reports—Europe 1
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Appendix F. Glossary 333 PVDF QCA Q
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Appendix F. Glossary 335 WTEC XAS X
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