Shigehiko Hayashi

Supported gold catalysts prepared by using nano-sized gold particles dispersed in nylon-11 oligomer

Gold catalysts supported on titanium oxide (TiO 2 ) have been prepared by using nano-sized gold particle/nylon-11 oligomer composites. The composite was prepared through vapor-deposition of gold onto a nylon-11 oligomer film followed by heat treatment. The gold particles/nylon-11 oligomer composite in solution was adsorbed rapidly on the surface of TiO 2 . When the gold particles/nylon-11 oligomer composite adsorbed on TiO 2 was calcined at various temperatures in air, nano-sized gold particles were supported directly on the surface of TiO 2 without coagulation. The catalytic activity of the gold particles for oxidation of CO was measured in a flow type reactor. The catalytic activity of gold supported on TiO 2 prepared by a one-stage calcination was not so high as that of gold catalysts reported previously. This result was considered to be due to growth of the size of the gold particles during calcination. When the calcination was carried out in two stages (the first at 500 °C in vacuum, and the second at 400 °C in air), the growth of the size of the gold particles was suppressed considerably. The supported gold catalyst thus obtained showed very high activity for the oxidation of CO, with a temperature of –10 °C for 50% conversion of CO.

Dispersion of nano-sized gold particles into polymers: dependence on terminal groups of polymers and morphology of vapor-deposited gold

Dispersion of nano-sized gold particles into polymers was investigated from the viewpoint of terminal groups and molecular motion of the matrix polymers, and from morphology of vapor-deposited gold. NH 2 -terminated poly(ethylene oxide) (PEO-NH 2 ) and poly(ethylene glycol) (PEG) were used as the matrix polymers. When gold with a thickness of 20 nm was vapor-deposited onto a melt of PEO-NH 2 at 60 °C, nano-sized gold particles were smoothly dispersed into the melt. On the other hand, gold vapor-deposited on a melt of PEG formed only conglomerates. When gold with a thickness of 3 nm was vapor-deposited onto PEO-NH 2 and PEG films kept at 20 °C, it formed particulate films. The gold particles formed were not dispersed into the polymer films by heat-treatment below the melting point of the polymer. However, when the polymer films were melted by heat-treatment at 50 °C, the gold particles were dispersed only into PEO-NH 2 . When gold with a thickness of 20 nm was vapor-deposited on the polymer films, it formed conglomerates, therefore the dispersion of gold particles into both polymers was not observed even upon heat-treatment at 50 °C. Measurements of spin-spin relaxation time by solid-state 1 H NMR indicated that the molecular motion of PEO-NH 2 was restricted below the melting point. Therefore, the dispersion of the nano-sized particles occurred only above the melting point of PEO-NH 2 .

Crystal growth of tetraphenylporphyrin thin films

The crystal growth and the orientation of thin films of 5,10,15,20-tetraphenylporphyrin (H 2 TPP) vacuum-evaporated onto substrates of a KCl (001) surface and a semitransparent A1 electrode film have been investigated by electron microscopy and electron diffraction. The films deposited on a KCI (001) surface show epitaxial growth in which the crystals take a four-directional orientation, and the molecular plane of HzTPP stands perpendicular to the substrate surface. The H 2 TPP crystals with a morphology of rectangular islands grow on the KCI surface kept at 200 ° C, while a continuous thin film totally covers the KCI surface kept at 20 ° C with an identical epitaxial orientation. When H 2 TPP is deposited on a KCI (001) surface coated partially with a small number of Al particles, the crystals take the same orientation. This epitaxial orientation decreases with increasing the coverage of the A1 particles on the KCI surface, and the H 2 TPP film deposited on a semitransparent A1 film shows a random orientation of needle-like crystals. The growth of the thin film with oriented crystals depends on the electrostatic interaction of the H 2 TPP molecules with ionic charges on the KCI surface.

Crystal growth of octacyanometalphthalocyanine-metal complexes in thin films

Abstract Octacyanometalphthalocyanine-metal complex (MPc(CN) 8 −M, M = Cu, Ni, Co, Fe, Zn and K 2 Pc(CN) 8 − K ) crystals were synthesized by vapor-solid reaction of tetracyanobenzene (TCNB) with metal films and a KCl crystal. Their crystal growth was investigated by electron microscopy. The crystal morphology depended on reaction temperature, pressure and kinds of substrate. Crystals of MPc(CN) 8 −M and K 2 Pc(CN) 8 −K grew long and thick, tentacle-like, on polycrystal metal films and on a KCl (001) surface at the reaction temperature of 350°C. Growth of the crystals was inactive at reaction temperatures below 300°C. Crystal defects such as bends and folds increased with rising reaction pressure. The growth mechanism was assumed as follows: MPc(CN) 8 molecules are formed on a substrate metal by tetramerization of TCNB vapor, and peripheral nitrile groups of MPc(CN) 8 molecules coordinate to metal atoms of the substrate to form a MPc(CN) 8 − M complex. MPc(CN) 8 molecules are piled up in parallel to form a column structure and the complex crystal grows by diffusion of metal atoms from the substrate. The crystal growth is well-defined when metal atoms are supplied sufficiently from the substrate.

Measurement of Growth Information of a Strawberry Plant Using a Natural Interaction Device

This paper details a measurement procedure for acquiring growth information on strawberry plants, such as height, width, volume, leaf area, leaf inclination and leaf color using a relatively inexpensive natural interaction device (NID). An NID is a motion-sensing device that is mainly used as a game controller, for example, Microsoft’s Kinect sensor, that can detect the movements of players by means of a color camera and depth sensor. It captures RGB images of 640 x 480 resolution along with per-pixel depth information. We installed an NID on a circulating-type movable bench system for strawberry cultivation. Since all the plants pass under the NID during the cultivation system, color and depth images of all the plants can be obtained. Using an image-processing method based on grayscale matching, color and depth images of every bench were smoothly tiled. Whole-leaf regions for every bench were then derived. To analyze the color and depth images in the whole-leaf regions efficiently, image-processing software was developed to extract and map the growth information on strawberry plants on the movable bench system. To evaluate the accuracy of our measurement procedure, we compared the actual data on height, width, and leaf area with their estimated values. The results showed each coefficient of determination to exceed 0.8. The maps created revealed significantly local biases of plant growth that varied according to strawberry cultivar.

Epitaxial growth of tetraphenylmetalporphyrin films vapor-deposited on alkali halides

Abstract Tetraphenylmetalporphyrins with central metals and axial ligands of VO, Zn·H 2 O and Mg·H 2 O (MTPPL) were vacuum-deposited on the cleavage faces of KCl and KBr. The deposited films were investigated by electron microscopy and X-ray and electron diffraction. The films were composed of rectangular crystals with body-centered tetragonal lattice, with their (001) planes oriented parallel to the substrate surface. The molecular image observed by high-resolution electron microscopy displayed that their molecular planes oriented parallel to the substrates. The epitaxial nucleation was explained in terms of the Coulomb interaction either between the central metal atom and the negative halide ion or between the ligand atom and the positive potassium ion. On the KCl substrate, the 〈100〉 directions of the MTPPL crystals ran along the 〈120〉 direction of KCl, while on the KBr substrate, they ran along the 〈100〉 direction of KBr. The different directions of crystal growth may be attributed to the lattice matching between the substrate and the deposited crystals.

Epitaxial Growth of 5,10,15,20-Tetraphenylporphyrin Metal Complexes and Their Photovoltaic Properties

Abstract Epitaxial growth of 5,10,15,20-tetraphenylporphyrin metal complexes (MTPP; M = Zn, Mg, Co, VO) and their photoelectrochemical properties were investigated. MTPP crystals grew epitaxially on a KC1 (001) surface by a physical vapor deposition method. All the crystals belong to the tetragonal system. The (100) plane of MTPP crystals is parallel to the KC1 (001) plane, and the [100] axis is parallel to the KC1 (120) axis. Photoelectrochemical properties were measured in the indium-tin oxide(ITO)/MTPP/Ia-,I-/Pt system.

Epitaxial growth and molecular orientation of tetra (4-pyridyl) porphyrin thin film vacuum-evaporated on KCl

Abstract 5,10,15,20-tetra (4-pyridyl) porphyrin thin films were vacuum-evaporated onto a KCl (001) surface. The orientation of the thin film was investigated by electron microscopy, and X-ray and electron diffractions. The film was composed of crystallites which have orthorhombic lattice with dimensions of a = 2.12 nm, b = 0.68 nm, and c = 2.18 nm. The crystal grew epitaxially on a KCl (001) surface with its (001) plane parallel to the KCl (001) plane. A column structure observed by high-resolution electron microscopy showed molecules packed in thin crystals. The molecular planes of the porphyrin were oriented almost perpendicularly to the KCl (001) plane. The crystals grew along three different directions against the KCl direction, the angles between the column axis and the KCl [100] direction were 0°, 27°, and 45°.

Preparation of the composite consisting of nano-sized gold particles and Nylon-11 oligomer

Nylon-11 oligomer was utilized as a matrix to prepare a composite containing nano-sized gold particles. Nylon-11 oligomer was prepared by a thermal degradation of a commercial nylon-11 in vacuum. Weight-average molecular weight of the oligomer was in a range from 500 to 800. Nylon-11 oligomer was formed into a film, and then gold was vapor-deposited onto the oligomer film. The gold-colored oligomer film turned a transparent red after a heat treatment at 120°C. Transmission electron microscopy showed an isolated distribution of nano-sized gold particles in the red film of the oligomer. The gold particles were stable in the oligomer for more than a year, and they were dissolved in CH 2 Cl 2 to produce a stable colloidal solution. These results suggest that the gold particles were not only dispersed in the oligomer film, but they were stabilized by the nylon-11 oligomer to form a composite. IR spectrum of the composite showed that N-H groups of the nylon-11 oligomer were responsible for the interaction between the gold particles and the oligomer. Pulse 1 H-NMR measurement suggested that an active molecular motion of the nylon-11 oligomer caused the dispersion of the gold particles.