Site: Osaka National Research Institute (ORNI)
Interdisciplinary Basic Research Section
AIST, MITI
1-8-31 Midorigaoka
Ikeda 563, Japan
Tel: (81) 727-51 9690; Fax: (81) 727-51 9630

Date Visited: 24 July 1997

WTEC: D.M. Cox (report author), C. Koch, J. Mendel, H. Morishita, R.W. Siegel

Hosts:

BACKGROUND

This WTEC site visit was hosted by Dr. Masatake Haruta, the Chief Senior Researcher at Osaka National Research Institute (ONRI), who presented an excellent overview of the AIST laboratories under MITI. ONRI is one of 15 national laboratories, of which 8 are located in Tsukuba. ONRI, founded in 1918, is the fourth oldest research institute of MITI. At ONRI there are five major research departments and one research section:

These research departments focus on three primary areas: (1) energy related materials, (2) optical materials, and (3) fundamental research. The major components of energy related materials are energy storage using new battery technology; molten carbonate fuel cells; production, storage, transportation, and application of hydrogen energy; and catalysis. In optical materials the focus is on nonlinear optical materials and application of optical measurements. In fundamental research the focus is on thin film and ion beam technology, material design and characterization, and bioengineering of molecular complexes of peptides.

RESEARCH AND DEVELOPMENT HIGHLIGHTS

ONRI is very proud of its history of contributions to industry, with several major inventions, discoveries, and developments in the labs at Osaka. Four of these are

  1. polyacrylonitrile (PAN)-based carbon fibers, which are used as carbon fiber reinforcements for plastics used in golf club shafts and fishing rods, as well as for aerospace applications
  2. transparent conductive films of indium oxide (and tin oxide) via vacuum deposition, which advanced liquid crystal technology; the transparent conductive films are also used commercially as anti-icing coatings and have been applied to windshields of the Tohoku-Shinkansen bullet trains
  3. inorganic spherical microcapsules with porous walls, with applications in cosmetics and deodorants
  4. the discovery that nanosized gold catalysts have specific catalytic properties useful for odor removal, specifically for rest rooms; this work is a recent invention from Dr. Haruta's group

Dr. Haruta, our host, in addition to his responsibilities as Chief Senior Researcher at ONRI, is head of the Interdisciplinary Basic Research Section, which was founded in 1994 as a new research section for basic studies, with a primary aim to provide fundamental knowledge to the science world.

The technical update was provided by Dr. Haruta plus several other members of his group, Drs. Tsubota, Okunura, Cunningham, Ando, and Fukumi. The work on "gold catalysts" is a major focus for ongoing research and has led to the discovery that supported gold catalysts exhibit unique catalytic properties only in the case where the gold particles are nanoscale and highly dispersed (gold particles on the order of 1-5 nm in diameter supported on metal oxides such as TiO2).

S. Tsubota and M. Okumura described catalyst preparation techniques, characterization, and present understanding of the behavior of these materials as a function of particle size. Specifically, the particle size effects have been examined as a function of (a) the pH of the initial Au solution, (b) the effect of calcining temperature on the TiO2 supports, (c) comparison of 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 -70C. 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 50C as well as near room temperature reduction of nitric oxide. A key scientific finding is the sensitive role that H2O 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 H2 and CO gases can be detected. The use of entirely optical techniques for selective detection of H2 was being promoted, since such detection would eliminate the possibility of fire ignition or explosion in H2 atmospheres. Dr. Ando summarized the optical gas sensor work as follows:

The results open the possibility for strictly optical recognition of H2 and CO.

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 1016-1017 Au+ ions/cm2. Characterization by TEM showed the average particle size was 8.6 nm diameter. In these materials, the third order nonlinear susceptibility X3 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.


Published: September 1999; WTEC Hyper-Librarian