[en] It is important to establish an accurate heat measurement system to confirm the excess heat from the cold fusion phenomenon. During plasma electrolysis, an accurate heat measurement is especially difficult, because the input power is large and it causes significant evaporation of electrolyte and heat loss to the environment from the body of the electrolytic cell. In this study, a flow calorimetry system has been developed for accurate measurement. The energy balance of plasma electrolysis was measured at 100-102%, and the current efficiency were from 115 to 122% during the plasma electrolysis in 0.3 mol/dm³ Na₂CO₃ light water solution. Clear excess output energy has not been observed. Excess gases of 15-22% generation beyond Faraday's law was confirmed. The excess gas generation might be due to a plasma reaction. (author)

[en] In our previous study, we prepared tantalum oxide-based cathodes from oxy-tantalum phthalocyanines by heat treatment under low oxygen partial pressure for polymer electrolyte fuel cells. We revealed that the high onset potential for oxygen reduction reaction (ORR) indicated a low hydrogen peroxide formation rate due to the large extent of crystalline distortion of orthorhombic Ta₂O₅. However, the hydrogen peroxide formation rate was consistent with an apparent four-electron reaction rate because it included the effect of the hydrogen peroxide reduction reaction. Therefore, in this study, we calculated the individual rate constants of the ORR for tantalum oxide-based cathodes to obtain the four-electron reaction rate (four-electron reduction rate of O₂/two-electron reduction rate of O₂) and investigated the factors influencing the four-electron reaction rate. The values of the four-electron reaction rate for the tantalum oxide-based cathodes were larger than 1, indicating that the four-electron reaction mainly occurred on the oxide surface. A higher four-electron reaction rate was obtained in the case of severe crystalline distortion and shrinkage of orthorhombic Ta₂O₅ due to the large number of oxygen vacancies.

[en] The development of non-platinum-based cathodes is required in order to commercialize polymer electrolyte fuel cells. We have previously investigated group 4 and 5 transition metal oxides because they exhibit high chemical stability under cathode conditions and are less costly than platinum. In this paper, tantalum oxide-based cathodes were prepared from oxy-tantalum phthalocyanines by heat treatment under low oxygen partial pressures. We successfully obtained nano-sized tantalum oxide-based particles dispersed on multi-walled carbon nanotubes to increase the oxygen reduction reaction (ORR) current density. We investigated the factors which influence ORR activity in terms of the onset potential and ORR current density. The onset potential increased with increasing crystalline distortion of orthorhombic Ta_2O_5, which was experimentally observed as changes in the position and full width at half maximum of the Ta_2O_5 (0 0 1) peak in the X-ray diffraction patterns. In addition, the amount of the deposited carbon strongly influenced the ORR current density because it affected the surface area of the oxides and the formation of local electron conduction paths.