The growth and properties of Au oxide films formed on an Au electrode in a 0.1–1.0 M NaOH solution were investigated using potentiostatic and cyclic voltammetric techniques. Scanning electron microscopy images showed the structure of an Au oxide film on an Au electrode at various oxidation potentials: 1.5, 2.0, 2.5, and 3.0 V. The Au oxide electrode was used to determine oxidation potential of heterocycles thiazole in phosphate buffer (pH 2.21). The potential peaked at 0.54 V for rhodanine, 0.40 V for thiazolidine-2,4-dione, 0.47 V for thiazolidine, and 0.48 V for L(−)-thiazolidine-4-carboxylic acid. Compared with the results obtained from an Au oxide electrode, the peak potential of heterocycles thiazole was less positive and the peak current 3–15 times higher than that of the peak potential found using a bare gold electrode.
The decomposition of simple organic chlorides (carbon tetrachloride, CCl4 and mono-chlorobenzen, C6H5Cl) as the imitation substances of polychlorobiphenyls (PCBs) were investigated by using basic molten salts with a low melting point and oxidizing ability in order to establish a safe, simple and highly efficient decomposition process. CCl4 or C6H5Cl was injected together with an inert carrier gas (Ar) into basic molten salts (KOH-K2CO3) at 673–983 K, and the residual concentration in the exhaust was measured. The decomposition efficiency of CCl4 strongly depended on the reaction temperature and the immersion depth of gas injection nozzle (related to the residence time of CCl4 bubble in the molten salts). The decomposition efficiency reached to very high of 99.9% with KOH-20 mol% K2CO3 at 973 K. On the other hand, the decomposition efficiency of C6H5Cl was not so high (97%) in the inert atmosphere condition applied in this study.
The polymer electrolyte fuel cell is expected as the power source for vehicle. However, high current density operation of the fuel cell is demanded for a cost cut, miniaturization and weight saving of the fuel cell system. The electrode which can evacuate cathode generated water efficiently is necessary for stable generation in high current density area. In this article, we paid our attention to MPL which constitutes GDL of a fuel cell electrode. And especially we made a study on MPL which can perform evacuation of generation water easily. As a result, we made the porous particles which consist of carbon black and PTFE using the spray dry method and we showed the MPL which consisted of the particles. This MPL had both pores of less than 1 µm in diameter that is effective in movement of the gas and pores of 1–10 µm in diameter that is effective in evacuation of generation water. Furthermore, the possibility that this MPL could contribute to high current density operation of the fuel cell was verified experimentally.
We investigated the conceptual design policy for CO2 gas reduction of 25% below 1990 levels by 2020. The electric power supply of Japan in 2020 was estimated 956.5 TWh. The LNG generation plant and the generation plant using renewable energy are the proper generation method from the point of view of 1) safety, 2) CO2 gas reduction, 3) economy, 4) resources, and 5) load following operation. We proposed an electric power supply system that the 80% of electric power supply of Japan in 2020 was supplied by SOFC-GT-ST hybrid system using LNG and the rest was supplied by generation plant using renewable energy. For the conceptual design policy for CO2 gas reduction of 25% released from generating station in 1990, we showed that SOFC-GT-ST hybrid system with generating efficiency of 70% (HHV, AC) was useful in reducing CO2 gas. In this system the generating efficiency of SOFC was required above 60% (HHV, DC). To improve the generating efficiency and the volumetric power density of SOFC, new bifacial flat tubular cell structure based on numerical analysis was proposed. Main feature of new cell structure is shown below. 1) 2 mm thin cell to shorten the current path and reduce the cell volume. 2) Interconnector divided into nine to shorten the current path. 3) Covering the cathode surface with the auxiliary electrode to reduce the cell resistance. 4) Porous flow path of anode to avoid partial flow. Prototype of proposed cell was analyzed and achieved 60% (HHV, DC) of generating efficiency and 2 W/cm3 of volumetric power density when the cell voltage was 0.77 V.
An experimental study was carried out to find how to upgrade surface properties of carbonaceous porous materials used as an electrode substrate in Phosphoric Acid Fuel Cells. The porous materials were made by forming of carbon fibers prepared through ozone treatment (OCF hereafter) with resin binders, and then baking and graphitization were performed. Comparison was performed with those prepared by use of carbon fiber as received (NCF hereafter). As a result, the ozone treatment affected greatly to the performance of the porous materials, showing decrease of electrochemical corrosion loss in 20% by weight compared to the one made by using NCF. The porous material made of OCF showed approximately 4% higher porosity and 30% lower specific surface area than those of NCF. From the observation under an electron microscope, it was found the surface of OCF was covered more widely and uniformly by the binder than that of NCF, and the stress produced during carbonization of the binder brought larger shrinkage to the porous materials made of OCF, furthermore, graphitizability of the carbonaceous material made from binder was increased by the relaxation of remaining stress during the graphitization. There appeared no change in electrical and thermal conductivity, while a small decrease in mechanical strength was observed, due to the increase in the porosity. However, such disadvantage as above will be avoided by choosing binder content and forming pressure.