H. Hagiwara
Hydrogen Isotope Research Center, Organization for Promotion or Research, University of Toyama, Gofuku, Toyama 930-8555, Japan

Abstract
In heterogeneous photocatalysts, it is very important to move photoexcited charges in the semiconductor to the reaction site on the surface without recombination. In this review, we describe the process of the photocatalytic reaction from photoexcitation of semiconductor photocatalyst to surface redox reaction, and summarized various researches on the charge separation of photogenerated electrons and holes in semiconductors reported up to the present.

Masanori Hara^a, Haruna Sakaguchi^a, Masato Nakayama^a, Tsukasa Aso^b, Miki Shoji^c, Takayoshi Furusawa^d, Yuka Kato^d, Tomoyuki Yoshimura^d, Tomohiro Ozaki
^aHydrogen Isotope Research Renter, Organization for Promotion of Research, University of Toyama, Gofuku 3190, Toyama 930-8555, Japan ^bElectronics and Computer Engineering, Toyama National College of Technology, Ebie-neriya 1-2, Imizu city, Toyama 933-0293, Japan ^cLife Science Research Center, Organization for Promotion of Research, University of Toyama, Sugitani 2630, Toyama 930-0194, Japan ^dHitachi, Ltd., 6-22-1 Mure, Mitaka city, Tokyo 181-8622, Japan

Abstract
The modified integral counting method by control of the high voltage of photomultipliers (MICM-HV) was investigated to show its applicability for radioactivity analysis. In the MICM-HV, pulse height spectra of the sample are measured at various high voltages of photomultipliers in the liquid scintillation counter. The spectra are converted to integral spectra, which are extrapolated to give the convergence point. The counting rate at the convergence point corresponds to the disintegration rate of the sample. The MICM-HV determines the disintegration rate with one cocktail sample and the method requires no unquenched standard sample.

Keywords: Modified integral counting method, high voltage, photomultiplier, scintillator

Satoshi Akamaru, Masanori Hara
Hydrogen Isotope Research Center, Organization for Promotion of Research, University of Toyama Gofuku 3190, Toyama 930-8555, Japan

Abstract
The magnetic susceptibility and equilibrium pressure of a Pd–Ag–Rh ternary alloy and hydrogen system were simultaneously measured, and the relationship between the magnetic susceptibility and the amount of absorbed hydrogen was investigated. The magnetic susceptibility linearly decreased to a value approaching zero with increasing hydrogen content. A high hydrogen content with a magnetic susceptibility close to zero is consistent with a hydride phase. This behavior is similar to that of Pd–Ag or Pd–Rh binary alloys and hydrogen systems, suggesting that the amount of hydrogen absorbed by the Pd–Ag–Rh ternary alloy is correlated with its electronic band structure, as in the case of the Pd-binary alloys.

Mitsuhiro Inoue,1,3) Asuka Shima,2,3) Kaori Miyazaki,1) Teruhiro Senkoji,2,3) Omar Mendoza,2,3) Baowang Lu,1,3) Yoshitsugu Sone,2,3) Takayuki Abe1,3)
¹⁾ Hydrogen isotope research center, Organization for promotion of research, University of Toyama, Gofuku 3190, Toyama 930-8555, Japan
²⁾Japan Aerospace Exploration Agency,Jindaiji Higashi-machi 7-44-1, Chofu, Tokyo 182-8522, Japan
Yoshinodai 3-1-1, Chuo-ku, Sagamihara, Kanagawa 252-5210, Japan
³⁾JST-CREST

Abstract
A TiO₂-supported Ru–Ni alloy (Ru–Ni/TiO₂) catalyst (atomic ratio of Ru:Ni = 50:50) for the CO₂ methanation reaction was prepared by the polygonal barrel-sputtering method. Sputtering was performed with an area ratio of the Ru and Ni targets of 1:1, Ar gas pressure of 0.8 Pa, and AC power of the radiofrequency power supply of 100 W without heating. As a result, the Ru–Ni alloy nanoparticles were highly dispersed on the TiO2 particles used as the support. The particle sizes were distributed between 1 and 5 nm (average size: 2.5 nm), which is similar to the size distribution of a Ru/TiO₂ sample prepared by the same method in our previous study. However, the CO₂ methanation performance of Ru–Ni/TiO2 is not as high as that of the above-mentioned Ru/TiO₂ sample. This might be because of the lower catalytic activity of Ni than Ru.

Akira Taguchi*, Tomohiro Ozaki
Hydrogen Isotope Research Center, University of Toyama, Toyama 930-8555, Japan

Abstract

To understand the hydrogen absorption and desorption behaviors of Pd under air, we performed real time measurements of the electrical resistance of Pd under gas mixture with various oxygen contents. The hydrogen absorption rate was independent of oxygen concentration. Conversely, the hydrogen desorption rate in the presence of oxygen was faster than that without oxygen, suggesting that the additional desorption path including water formation reaction appears in the hydrogen desorption process in the presence of oxygen. The hydrogen concentration in Pd at equilibrium decreased with increasing oxygen concentration in gas phase because the hydrogen adsorption sites become partially occupied by oxygen atoms.