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Kato, Sho; Yamaki, Tetsuya; Yamamoto, Shunya; Hakoda, Teruyuki; Kawaguchi, Kazuhiro; Kobayashi, Tomohiro*; Suzuki, Akihiro*; Terai, Takayuki*
Nuclear Instruments and Methods in Physics Research B, 314, p.149 - 152, 2013/11
Times Cited Count：2 Percentile：19.68(Instruments & Instrumentation)We implanted 100 keV W
in unpolished GC substrates at nominal fluences up to 
ions/cm
. The implanted samples were electrochemically anodized in a NaOH aqueous solution to etch the surface layer. The analyses were performed by X-ray photoelectron spectroscopy (XPS), Rutherford backscattering spectrometry (RBS), and transmission electron microscopy (TEM). XPS W 4f spectra indicated the formation of carbides as reported previously. The electrochemical etching clearly increased the W concentration on the surface. According to the RBS results, half of the implanted W atoms were retained in the substrate, while the rest should escape to the etching solution. The cross-sectional TEM image revealed a uniform distribution of WC particles with a diameter of less than 10 nm just near the surface region.
Kato, Sho; Yamaki, Tetsuya; Yamamoto, Shunya; Hakoda, Teruyuki; Kawaguchi, Kazuhiro; Kobayashi, Tomohiro*; Suzuki, Akihiro*; Terai, Takayuki*
Transactions of the Materials Research Society of Japan, 38(1), p.81 - 84, 2013/03
Nanoparticles were formed by 100 keV tungsten-ion implantation in unpolished glassy carbon substrates at nominal fluences of 
- 
ions/cm. The implanted samples were analyzed by Rutherford backscattering spectrometry, X-ray photoelectron spectroscopy, hydrodynamic voltammetry using a rotating disk electrode, and field emission scanning electron microscopy. A significant sputtering effect changed the depth profile during the course of irradiation and limited the amount of tungsten retainable in the substrate in agreement with our calculated distributions. The nanoparticles were composed of tungsten carbide and dispersed uniformly with diameters of around 10 nm.
Hakoda, Teruyuki; Yamamoto, Shunya; Kawaguchi, Kazuhiro; Yamaki, Tetsuya; Kobayashi, Tomohiro*; Yoshikawa, Masahito
Applied Surface Science, 257(5), p.1556 - 1561, 2010/12
Times Cited Count：13 Percentile：50.74(Chemistry, Physical)Carbon-based films having nitrogen species on their surface were prepared on a glassy-carbon (GC) substrate as a non-platinum cathode catalyst for polymer electrolyte fuel cells by depositing cobalt and carbon in the presence of N
gas using a pulse laser deposition method and then removing metal Co by HCl-washing treatment. The oxygen reduction reaction (ORR) activity was electrochemically determined using a rotating disk electrode system where the film samples on the GC substrate were replaceable. The ORR activity increased with elevating temperature of the GC substrate during the deposition. A carbon-based film prepared at 600
C in the presence of 66.7 Pa N showed the highest ORR activity among the tested samples; its ORR potential was 0.66 V (vs. NHE). This film was composed of amorphous carbons doped with pyridine-type nitrogen atoms on its surface.
Sumita, Junya; Sawa, Kazuhiro; Mogi, Haruyoshi; ; Kitami, Takayuki; Akutsu, Yoichi; *; *; *
JAERI-Research 99-054, p.41 - 0, 1999/09
JAERI-Research-99-054.pdf:1.19MB
no abstracts in English
*; *; *; *; *; Suzuki, Junichi; Funahashi, Satoru
Langmuir, 11, p.563 - 567, 1995/00
Times Cited Count：36 Percentile：82.5(Chemistry, Multidisciplinary)no abstracts in English
Cu
O
(R=Tm,Er,Ho,Y,Dy and Gd)*; *; *; Katano, Susumu; Funahashi, Satoru; *
Physica C, 219, p.176 - 182, 1994/00
Times Cited Count：30 Percentile：83.99(Physics, Applied)no abstracts in English
Yamamoto, Shunya; Hakoda, Teruyuki; Kawaguchi, Kazuhiro; Yamaki, Tetsuya; Yoshikawa, Masahito
no journal, ,
no abstracts in English
Hakoda, Teruyuki; Yamamoto, Shunya; Kawaguchi, Kazuhiro; Yamaki, Tetsuya; Kobayashi, Tomohiro*; Yoshikawa, Masahito
no journal, ,
no abstracts in English
Yamamoto, Shunya; Hakoda, Teruyuki; Kawaguchi, Kazuhiro; Yoshimura, Kimio; Yamaki, Tetsuya; Kobayashi, Tomohiro*; Yoshikawa, Masahito
no journal, ,
no abstracts in English
Yamamoto, Shunya; Hakoda, Teruyuki; Yamaki, Tetsuya; Kawaguchi, Kazuhiro; Yoshikawa, Masahito
no journal, ,
For practical use of polymer electrode membrane fuel cells, development of low Pt loading catalysts and non-Pt catalysts for an oxygen reduction reaction have been required. One promising non-Pt catalyst is based on the transition metal(TM)-nitrogen (N)-carbon(C) systems (TM: Fe, Co, Ni, etc.). In the present study, we prepared Fe and N doped carbon film on a glassy carbon (GC) substrate heated at different temperatures in the presence of N gas using a pulsed laser deposition (PLD). The ORR activity of the films was electrochemically determined using a rotating disk electrode system. The ORR activity of Fe-N-C films increased with elevating temperature (700-900C) of the GC substrate during the deposition. The Fe-N-C film prepared at 800C showed high ORR activity; its ORR potential was 0.76V (vs. NHE). Our preliminary results suggest that suitable concentration of doped Fe and deposition temperature make it possible to improve ORR activity of Fe-N-C films.
Yamaki, Tetsuya; Kato, Sho*; Yamamoto, Shunya; Hakoda, Teruyuki; Kawaguchi, Kazuhiro; Kobayashi, Tomohiro*; Suzuki, Akihiro*; Terai, Takayuki*
no journal, ,
We prepared nanoparticles of tungsten (W) carbides by W-ion implantation in an unpolished glassy carbon (GC) substrate and then examined, for the first time, their composition, electrochemical properties, and morphology. The W
implantation was performed at room temperature using an energy of 100 keV and nominal fluences of up to 1.8
10
ions/cm
. Due to a significant sputtering effect and chemical interation between the implants and substrate, mostly W carbides, a mixture of WC and WC phases, were formed on the surface. The subsequent electrochemical etching in an alkaline solution achieved the smooth surface with maximum area density of the carbide phases. Particulate aggregates were found to contain spherical nanoparticles with a diameter of 
10 nm.
Kato, Sho; Yamaki, Tetsuya; Yamamoto, Shunya; Hakoda, Teruyuki; Kawaguchi, Kazuhiro*; Kobayashi, Tomohiro*; Suzuki, Akihiro*; Terai, Takayuki*
no journal, ,
In this research, we prepared WC nanoparticles by tungsten ion implantation in glassy carbon. The GC plates were implanted with 100-keV tungsten ion at nominal fluences between 2.410
1.810 ions/cm by the Ion Implanter in TIARA. According to the Rutherford backscattering measurements, the implanted tungsten was distributed from 10 to 25 nm under the surface. The implanted samples were electrochemically etched to make the tungsten implanted layer exposed on the surface. The binding energy of W4f
obtained by X-ray photoelectron spectroscopy were 32.1 eV, which indicated the formation of WC as expected. The transmission electron microscope observation revealed that nanoparticles formation with diameters of less than 10 nm.
Kato, Sho; Yamaki, Tetsuya; Yamamoto, Shunya; Hakoda, Teruyuki; Kawaguchi, Kazuhiro*; Kobayashi, Tomohiro*; Suzuki, Akihiro*; Terai, Takayuki*
no journal, ,
Glassy carbon substrates were implanted with 100-keV platinum ions at fluences between 710
and 410 ions/cm. The unimplanted samples were surface-etched electrochemically and thermally treated in order to prepare platinum nanoparticles on their topmost layer. Scanning electron microscope observation revealed the platinum nanoparticles with a diameter of a few tens of nanometers on the surface. The voltammogram using a rotating disk electrode showed large cathodic current due to oxygen reduction reaction activity of the obtained nanoparticles.
Yamaki, Tetsuya; Kato, Sho; Yamamoto, Shunya; Hakoda, Teruyuki; Kawaguchi, Kazuhiro*; Kobayashi, Tomohiro*; Suzuki, Akihiro*; Terai, Takayuki*
no journal, ,
Chemical transformations involved during ion implantation can lead to material modifications. Our focus here was on the interaction of tungsten (W) ions implanted in glassy carbon (GC). Recent studies dealt with nanosized particles of W carbides in a W-ion-implanted GC substrate in terms of their composition, electrochemical properties, and morphology. In this paper, we discuss a detailed study of compound formation resulting from W implants in GC for the first time, emphasizing the importance of chemical interactions in determining the final properties of the implanted layer.
Kato, Sho; Yamaki, Tetsuya; Yamamoto, Shunya; Hakoda, Teruyuki; Kawaguchi, Kazuhiro*; Kobayashi, Tomohiro*; Suzuki, Akihiro*; Terai, Takayuki*
no journal, ,
Ion implantation is a kind of technique to prepare nanoparticles. To prepare platinum (Pt) nanoparticle catalysts, it is very important to control their size. In this research, the process of particle growth was elucidated by in-situ transmission electron microscopy. In the experiment, glassy carbon substrates were implanted with 100 keV Pt ions at the fluences of 710410ions/cm. The electrochemical etching was applied to expose the implanted layer. Finally, thermal treatment was conducted to form nanoparticles. Before the thermal treatment, the each implanted Pt were seemed to be monoatomic. When the temperature of the sample reached 375C, the Pt atoms started to aggregate, and formed uniformly dispersed nanoparticles with diameters of 5 nm. This result indicated that the controllability of our nanoparticle preparation method is high enough to prepare the Pt nanoparticle for cathode catalysts in fuel cells.
Kato, Sho; Yamaki, Tetsuya; Yamamoto, Shunya; Hakoda, Teruyuki; Kawaguchi, Kazuhiro*; Kobayashi, Tomohiro*; Suzuki, Akihiro*; Terai, Takayuki*
no journal, ,
Pt nanoparticle catalysts prepared by ion implantation are expected to show high durability in fuel cell applications. In this research, the electrochemical stability of the Pt nanoparticles as oxygen reduction catalyst was evaluated.
Kato, Sho; Yamaki, Tetsuya; Yamamoto, Shunya; Hakoda, Teruyuki; Kawaguchi, Kazuhiro*; Kobayashi, Tomohiro*; Suzuki, Akihiro*; Terai, Takayuki*
no journal, ,
Platinum nanoparticle catalysts for fuel cell applications were prepared by ion implantation in a glassy carbon substrate followed by electrochemical etching and thermal treatment. Interestingly, they had a strong interaction with the substrate via platinum-carbon bonds, probably thereby achieving high catalytic activity for the oxygen reduction reaction.
Kato, Sho; Yamaki, Tetsuya; Yamamoto, Shunya; Hakoda, Teruyuki; Kawaguchi, Kazuhiro*; Kobayashi, Tomohiro*; Suzuki, Akihiro*; Terai, Takayuki*
no journal, ,
Platinum nanoparticle catalysts for fuel cell applications were prepared by ion implantation in a glassy carbon substrate followed by electrochemical etching and thermal treatment. Interestingly, they had a strong interaction with the substrate via platinum-carbon bonds, probably thereby achieving high catalytic activity for the oxygen reduction reaction.
Yamaki, Tetsuya; Kato, Sho*; Yamamoto, Shunya; Hakoda, Teruyuki; Kawaguchi, Kazuhiro*; Kobayashi, Tomohiro*; Suzuki, Akihiro*; Terai, Takayuki*
no journal, ,
A glassy carbon (GC) substrate was implanted with 100 keV tungsten (W) and platinum (Pt) ions at different fluences in order to prepare nanoparticles of W-carbides and Pt-metal, respectively, with diameters of 10 nm. We discuss a detailed study of compound formation and binding interaction resulting from the W or Pt implants in GC for the first time, emphasizing the importance of chemical effects in determining the final properties of the implanted layer. The chemical effects between the implanted species and the GC substrate were investigated mainly by X-ray photoelectron spectroscopy (XPS) while the morphological properties, i.e., the dispersion states of the implants or the size and shape of the precipitated nanoparticles, were observed by transmission electron microscopy (TEM).
Segawa, Tomoomi; Kawaguchi, Koichi; Ishii, Katsunori; Tamaru, Ayaka*; Yamada, Masaaki*; Fukasawa, Tomonori*; Ishigami, Toru*; Fukui, Kunihiro*
no journal, ,
The microwave heating method is used in the reprocessing process of spent fuels. To improve the powder quality in fuel fabrication for the fast reactor, research and development of a microwave hybrid heating method, which combines microwave heating with external heating, is advanced. However, the installation of heating equipment in the cavity may cause damage to the heating equipment due to electrical discharge or induced current under microwave irradiation. To evaluate the effect of the CNT content of the alumina composite on the microwave heating characteristics in detail, the temperature during microwave irradiation and the apparent dielectric loss were measured. As a result of this study, it was found that the microwave heating property can be controlled by adjusting the CNT content, and the prospect that CNT-containing alumina is effective as microwave absorbing heating material was obtained.
