There exist two types of photo-induced effects on TiO2 surface. One is the conventional photocatalytic reaction and the other is photo-induced highly hydrophilic conversion, proceeding on the TiO2 surface irradiated with UV light. Various materials coated with TiO2 transparent films can show self-cleaning, anti-fogging, and cooling effects with small amount of water. Their industrial applications are also introduced. Moreover, the mechanism for the highly hydrophilic conversion is suggested, considering the recent experimental results. That is, not the conventional photocatalytic decomposition of the strains on the TiO2 surface but the increase in the amount of hydroxyl groups on its surface irradiated with UV light is responsible for the hydrophilic conversion.
Anodic porous alumina, which is formed by anodization of Al in an appropriate acidic solution, has recently attracted increasing attention as a key material for fabrication of functional nanodevices due to its naturally occurring self-ordered structure. We describe here the fabrication of the anodic porous alumina with modified pore shapes and its applications for template processes. Highly ordered anodic porous alumina with square and triangular cross sections were prepared based on the control of the initiation site of the hole development. The preparation of initiation sites for the hole development was carried out by imprinting Al using a mold with a patterned array of convexes. The obtained anodic porous alumina with modified pore shapes is useful as templates for the fabrication of several types of nanostructures.
Features of the nanofabrication and device formation processes utilizing the reactions at solid/liquid interfaces, such as electrodeposition and electroless deposition, were overviewed and some of the recent applications were introduced. The features of the processes were compared with those using the physical deposition processes, and then the fabrication process using “through-mask” and “maskless” approaches were explained. As for the “through-mask” processes, the microscale electrodeposition process for the fabrication of the array of mushroom-shaped metallic absorber for the high sensitive X-ray imaging sensor, the so called X-ray microcalorimeter array, was explained. The electroless deposition process of CoNiP to form the array of magnetic nano dots was also introduced. On the other hand, the maskless and electroless fabrication process of the pattern of metallic nano dots on Si wafer surfaces was also explained, which utilized the local deposition activity induced at the nanoscopic defect sites on the wafer surface.
Electron injection processes in dye-sensitized solar cells have been studied. Transient absorption spectra were measured in a wide wavelength range (400—3000 nm) to probe photoproducts, oxidized dyes and conducting electrons. We estimated the efficiency of electron injection as a function of free energy change (ΔG)and found that surface of nanocrystalline films is energetically heterogeneous. Using a femtosecond spectrometer, we observed that electron injection occurs through several pathways, i.e., direct injection into the conduction band and injection via exciplex-like intermediates.
Our recent research on electrocatalysts for polymer electrolyte fuel cells has been reviewed. An electrocatalytic activity of Pt for O2 reduction was enhanced significantly by alloying Pt with Fe, Co and Ni. Alloys of Pt-Fe, Pt-Co and Pt-Mo were found to exhibit excellent CO-tolerance at H2 oxidation. From various analyses, it was found that the surfaces of all the alloys used are composed of a thin Pt layer with an electronic structure different from that of pure Pt, indicating an increased in 5d vacancy of Pt. For methanol oxidation reaction (MOR), we successfully evaluated the activities of Pt-Ru alloy and Pt electrodes in a wide temperature range from 20 to 120oC by using a thin-layer flow cell under pressurized operation. Adsorbed water molecules that promote the MOR at Pt-Ru alloy electrode were clearly detected by in situ FTIR spectroscopy, which directly supports the “bi-functional mechanism” for the MOR.
Electrochemical properties and electron transfer processes of biopolymers such as metal proteins or enzymes have been studied extensively, since it provides us important information to understand the redox system in biosystems. However, for example, it is not easy to obtain the reversible electrochemical response of superoxide dismutase (SOD) which dispropornations superoxide to molecular oxygen and hydrogen peroxide catalytically. Recently, electrochemical properties of various types of SODs have been reported using the so called self-assembled monolayer-modified electrodes or other type of functional electrodes. However, the results reported are not necessarily in good agreements. The authors introduce the modified electrode system for CuZnSOD reported by other research groups and describe the redox response of various SODs including CuZnSOD studied by our research group in this article.
Recent progress in understanding molecular mechanism of cell adhesion has prompted researches for designing interfaces to regulate cell adhesion in μm scale. Such cellular micropatterning has been extensively attempted by a number of research groups, since the spatial control of cellular adhesion and growth is a critical issue in many areas of biotechnology such as tissue engineering, cell-based bioanalysis and bioelectronics. We report herein our recent results on 1) the development of techniques for cellular micropatterning and 2) the characterization of the functions of micropatterned cells and cellular networks. The well-known “microcontact-printing” andthe newly developed “electrochemical lithography” were applied to prepare the single-cell alignments. The cellular activity was found to be regulated by the cell shape. The patterned cardiomyocytes connected each other via gap junctions and served as a pharmacological model of cardiac tissue.
Type of conductively and carrier concentration of a semiconductor sample with three different dopant regions were measured by scanning nonlinear dielectric microscope (SNDM). It is an application of SNDM in to scanning capacitance microscopy with a new detection mechanism that is based on frequency detection. In principle, SNDM includes the SCM function; it is possible to measure not only the conductive type distribution as a conventional SCM, but also the carrier concentration distribution at the same time. As a demonstration, the influence of an adsorbed water layer on the measurements of a semiconductor sample is observed.
Technologies that prevent housing equipments from the deposition of stains have been developed in our company. Among them, a new technology to prevent a toilet bowl from stains is introduced in this report. The toilet bowl is soiled with two types of stains. The one is the inorganic scale that covers to the dried surface of the toilet bowl, and the other is the organic slime that covers the surface soaked in water. Because the inorganic scale is considered to be caused by adhesion of the silicate in tap water, it could be prevented by coating organic molecule on the bowl surface. On the other side, the organic scale that is considered to be caused by the propagation of bacteria could be solved by antibacterial technology. In this way, different problems of deposited stains must be prevented by different approaches.