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Hakoda, Teruyuki; Yamamoto, Shunya; Aritani, Hirofumi*; Yoshikawa, Masahito
JAEA-Review 2013-059, JAEA Takasaki Annual Report 2012, P. 127, 2014/03
Reduction of noble metal ions and subsequent production of noble metal particles in a solution has been performed as a radiation-induced precipitation (RIP) method using high energy ionizing radiation. Electron beams with energies below 300 keV have shorter penetration range and can irradiate at higher dose rates. Application of such low energy EBs to the RIP method has a possibility of producing film matters consisting of noble metal particles on the surface of the solution. In the present study, this possibility was examined using a few ten keV EBs for PtCl
ion solutions. Black-colored film matters were produced on the surface of the sample solution after EB irradiation. Lower concentrations of ethanol such as 0.5v% accelerated the formation of Pt films on the sample solution. The films had network structure consisting of connected Pt particles with sizes of 2-5 nm.
Hakoda, Teruyuki; Igarashi, Hidetoshi*; Isozumi, Yukihiro*; Yamamoto, Shunya; Aritani, Hirofumi*; Yoshikawa, Masahito
Journal of Physics and Chemistry of Solids, 74(2), p.200 - 204, 2013/02
Times Cited Count：3 Percentile：16.12(Chemistry, Multidisciplinary)The gasochromic property of dehydrogenation-catalyst loaded tungsten trioxide (M/WO
) powders was examined in exposure to gaseous cyclohexane under different kinds and contents of catalysts, catalyst temperatures, and cyclohexane concentrations. The change in the intensity of visible lights reflected from the M/WO powders was in situ obtained using a portable visible-light spectrometer. The catalyst of Pt was a catalyst initiating dehydrogenation and the change of reflected light intensity at lower temperatures in comparison with the catalysts of Pd and Rh. Among 0.1, 0.5, and 1wt% Pt/WO powders, the 0.5wt% Pt/WO powders demonstrated large change of reflected lights. The heating of 0.5wt% Pt/WO powders at temperatures higher than 130
C was required to visually detect cyclohexane at a concentration of 1v%, lower than the combustion lower limit (1.3v%).
Isozumi, Yukihiro; Hakoda, Teruyuki; Yamamoto, Shunya; Aritani, Hirofumi*; Yoshikawa, Masahito
Radioisotopes, 61(6), p.289 - 296, 2012/06
In the present study, the reduction of PtCl ions and subsequent formation of Pt particles were examined for a few tens keV EB irradiation of PtCl ion solution in the presence of 1-20wt% ethanol as an OH radical scavenger. As a result, the reduction of PtCl ions proceeded in whole solution by irradiating only the topmost surface layer of the solution, and these Pt particles with sizes of 2-5 nm would be produced as primary particles through reduction of PtCl ions. Moreover, these Pt particles were observed to have hydrogen dissociation activity and oxidation activity.
Isozumi, Yukihiro; Suzuki, Ryuta*; Hakoda, Teruyuki; Yoshikawa, Masahito; Aritani, Hirofumi*
no journal, ,
The organic hydrides has been focused as a substance that stores and transports hydrogen safely, therefore the optical sensor to detect its leakage has been needed for its flammability. In recent studies, some kind of dehydrogen metals over WO gasochromic substrate have been developed for the sensor, but dehydro-mechanism over these metals was not clear because WO absorb hydrogen produced through dehydrogenation. In the present study, the dehydrogen reaction over these metals was evaluated by comparing the dehydrogen activity over catalyst metals over different substrates including WO. It was confirmed that Pt had a dehydro-activity at the lowest reaction temperature and produced the amount of benzene was equal to that of consumed cyclohexane stoichiometrically. Sintering of Pt over the WO substrate also caused deactivation gradually up to 125C.
Isozumi, Yukihiro; Hakoda, Teruyuki; Yamamoto, Shunya; Aritani, Hirofumi*; Yoshikawa, Masahito
no journal, ,
We confirmed reduction of Pt ion, preparation of particles and catalytic activity of these particles in 10mL solution including 5mM Pt ion and ethanol induced by low energy electron beam(EB) irradiation that has a high dose rate to confirm the availability of radiation induced reduction using low energy EB for one kind of method, it prepare noble metal particles having catalytic activity. The maximum dose of Pt particles was shown in a 10% ethanol. Diameters of these Pt particles that were produced in this irradiated solution were mostly 2 to 5nm, and a part of these particles coagulated each other to become particles with sizes of a few tens to a few hundred nm. The fact these Pt particles has a hydrogen dissociation catalytic ability was induced by the coloration of tungsten trioxide, which is one of hydrogen gasochromic materials. These results suggest that low energy EB irradiation is applicable method for preparation fine noble metal particles having catalytic activity.
Hakoda, Teruyuki; Isozumi, Yukihiro*; Yamamoto, Shunya; Aritani, Hirofumi*; Yoshikawa, Masahito
no journal, ,
In the present study, the reduction of PtCl
ions and subsequent formation of Pt particles were examined for a few tens keV EB irradiation of PtCl ion solution in the presence of 5-20wt% ethanol as an OH radical scavenger. As a result, the reduction of PtCl ions proceeded in whole solution by irradiating only the topmost surface layer of the solution, and these Pt particles with sizes of 2-5 nm would be produced as a primary particle through reduction of PtCl ions. Moreover, these Pt particles was observed to have hydrogen dissociation activity and oxidation activity.
Hakoda, Teruyuki; Yamamoto, Shunya; Shimoyama, Iwao; Aritani, Hirofumi*; Yoshikawa, Masahito
no journal, ,
Water solution containing 1 mmol/L PtCl ions and 0.5-20v% ethanol was irradiated with low energy electron beams. Production of planar networks was observed on the surface of the irradiated solution. Rutherford backscattering spectrometry and X-ray photoelectron spectroscopy demonstrated that the planar networks consisted of metal platinum and their production was accelerated at lower ethanol concentrations. Transmission electron microscope observation suggested that Pt particles with sizes of 2-5 nm are produced through reduction of PtCl ions at the surface of the solution. These Pt particles coagulated each other to form planar network.
Hakoda, Teruyuki; Yamamoto, Shunya; Yoshikawa, Masahito; Isozumi, Yukihiro*; Aritani, Hirofumi*
no journal, ,
In the present study, the reduction of PtCl ions and subsequent formation of Pt particles were examined for a few tens keV EB irradiation of PtCl ion solution in the presence of 1-20wt% ethanol as an OH radical scavenger. As a result, the reduction of PtCl ions proceeded in whole solution by irradiating only the topmost surface layer of the solution, and these Pt particles with sizes of 2-5 nm would be produced as primary particles through reduction of PtCl ions. Moreover, these Pt particles were observed to have hydrogen dissociation activity and oxidation activity.
Hakoda, Teruyuki; Yamamoto, Shunya; Shimoyama, Iwao; Aritani, Hirofumi*; Yoshikawa, Masahito
no journal, ,
We previously observed that platinum nanoparticles films was produced on the surface of a solution containing 1 mmol/L PtCl ions and 0.5-20v% ethanol by irradiating with a few tens keV electron beams (EB). In the present study, the platinum films were deposited to tungsten trioxide (WO) films, which show hydrogen gasochromic property, to examine the catalytic property of the platinum films. The transmittance of 700-nm lights through the prepared (Pt/WO) films decreased in exposing to 1v% hydrogen/nitrogen gas. This decrease suggests the production of HxWO films through the reaction of WO films with hydrogen atoms dissociated over Pt nanoparticles. The Pt nanoparticle films prepared using a few tens keV EB induced reduction method were observed to have catalytic activity.
Hakoda, Teruyuki; Yamamoto, Shunya; Shimoyama, Iwao; Yoshikawa, Masahito; Aritani, Hirofumi*
no journal, ,
Water solution containing 1 mmol/L PtCl ions and 0.5-20v% ethanol was irradiated with low energy electron beams. Production of thin films were observed on the surface of the irradiated solution. Rutherford backscattering spectrometry and X-ray photoelectron spectroscopy demonstrated that the thin films consisted of metal platinum and their production was accelerated at lower ethanol concentrations. Transmission electron microscope observation suggested that Pt particles with sizes of 2-5 nm are produced through reduction of PtCl ions at the surface of the solution. These Pt particles coagulated each other to form the films.
Hakoda, Teruyuki; Yamamoto, Shunya; Aritani, Hirofumi*; Yoshikawa, Masahito
no journal, ,
The production of noble metal catalyst particles on the surface of catalyst substrates were studied using low energy electron beams (EBs) as a radiation-induced reduction method. Porous alumina substrates were impregnated in a solution containing PtCl ions and ethanol. The surface of the substrates was irradiated with EBs. As a result, platinum particles were produced on the surface of the substrates. The platinum particles had catalytic activity. The obtained results suggest that low energy EBs can be applied to the production of noble metal catalysts as new application of a radiation-induced reduction method.
Sugawara, Toshifumi*; Aritani, Hirofumi*; Hakoda, Teruyuki; Yoshikawa, Masahito
no journal, ,
We observed that platinum nanoparticles films were produced on the surface of a solution containing 1 mmol/L PtCl ions and 0.5-20v% ethanol by irradiating with a few tens keV electron beams (EB). The platinum films, deposited to grassy substrates, showed the fuel-cell catalytic activity. The Pt nanoparticle films prepared using a few tens keV EB induced reduction method were observed to have catalytic activity.
Yoshizawa, Reina*; Sugawara, Toshifumi*; Aritani, Hirofumi*; Shimada, Akihiko; Idesaki, Akira; Hakoda, Teruyuki; Sugimoto, Masaki; Yoshikawa, Masahito
no journal, ,
Carbon material which is manufactured after high temperature treatment of polymer is one of the candidates for the alternative of platinum cathode catalyst of polymer electrolyte fuel cell. In this study, we examine the influence of potential of oxygen reduction reaction by adding metal including material to polymer, precursor of carbon material. Specifically, 95 wt% of carboxymethyl cellulose (CMC) and 5 wt% of phthalocyanine (Pc) including metal or Pc were mixed. Adding water to this, the mixture of Pc-CMC were prepared. The mixture was irradiated by electron beam up to 100 kGy, dried and treated at 800 degree for 1 h in Ar gas. Then carbon material was manufactured. This was measured by electrochemical measurement. Then oxygen reduction reaction potential was calculated. The carbon material, CMC with Pc including Co has higher potential of 0.1 V than that with Pc including other metal or Pc. This phenomenon is the almost same as that manufactured by other polymer than CMC. It is estimated that Co is contributed to higher potential of oxygen reduction reaction.
Sugawara, Toshifumi*; Takahashi, Ayaka*; Aritani, Hirofumi*; Shimada, Akihiko; Hakoda, Teruyuki; Sugimoto, Masaki; Yoshikawa, Masahito
no journal, ,
We observed that platinum nanoparticles films were produced on the surface of a solution containing 1 mmol/L PtCl ions and 0.5-20v% ethanol by irradiating with a few tens keV electron beams (EB). The platinum films, deposited to grassy substrates, showed the fuel-cell catalytic activity. The Pt nanoparticle films prepared using a few tens keV EB induced reduction method were observed to have catalytic activity.
Takahashi, Ayaka*; Sugawara, Toshifumi*; Shimada, Akihiko; Hakoda, Teruyuki; Sugimoto, Masaki; Aritani, Hirofumi*; Yoshikawa, Masahito
no journal, ,
Recently, it is appeared that gold nano particles have catalytic activity of CO oxidation, though bulk gold does not have. The representative method to fabricate catalyst, impregnation, is rather complex method. This method is divided into sink, evaporation with mixing, drying, high temperature baking. If gold nano particle layer is fabricated, gold nano particle catalyst is fabricated only transferring to catalyst support material. Thus, we try to fabricate gold nano particle layer by electron beam irradiation from tetrachloroauric (3) acid solution, by radiation reduction method. One mmol/L tetrachloroauric (3) acid solution including 0.5 - 20% of ethanol was irradiated by electron beam (55 keV). Red, thin film-like-float (layer) is generated. This layer is measured by TEM and XPS. It is appeared that about 5 nm of nano particle (supposed to gold) is existed and most of the gold in the layer is zero valence (metallic) gold. So we show that gold nano particle layer is fabricated from tetrachloroauric (3) acid solution by radiation reduction method.
Hakoda, Teruyuki; Takahashi, Ayaka*; Shimada, Akihiko; Yamamoto, Shunya; Aritani, Hirofumi*; Yamaki, Tetsuya
no journal, ,
Aqueous solutions containing 1 mmol/L AuCl
ions and 0.5-20v% alcohol (2-propanol or ethanol) were irradiated with a few tens keV electron beams (EBs). Gold (Au) films were produced on the surface of the irradiated solution. The production rate of the Au films was high at concentrations of 0.5-1v% for 2-propanol and became lower at higher concentrations. At an alcohol concentration of 0.5v%, the Au particles of the films were 5-20 nm and 5-100 nm in diameter for 2-propanol and ethanol, respectively. The XPS analysis demonstrated that the films consisted of about 85wt% of metal Au(0), 10wt% of Au(I), and a few wt% of Au(III) for 2-propanol. A Fourier transform infrared diffusion reflectance (FTIR-DR) measurement showed that CO was oxidized into CO
over the Au films loaded to TiO substrates at a temperature of 200C, enabling us to confirm a catalytic activity.
