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367 results on '"Shinoda, Kozo"'

238. Synthesis of porous ?-Fe2O3 via alkaline treatment of size controlled scorodite particles synthesized using ultrasound irradiation and its evaluation as a cathode for lithium-ion battery

Author

Kitamura, Yuya, Okawa, Hirokazu, Shinoda, Kozo, Kato, Takahiro, Sugawara, Katsuyasu, and Suzuki, Shigeru

Abstract

Herein, we synthesized scorodite particles using ultrasound irradiation in a strong sulfuric acidic solution (pH 0.5) and investigated the scorodite particles' size and morphology. The highest crystallinity of scorodite (96%) was synthesized using 200 kHz ultrasonic treatment, and maximum yield of scorodite was obtained in three conditions: 200, 28 kHz, and stirrer. The oxidant generated through 200 kHz ultrasound irradiation enhanced Fe(II) oxidation in the solution resulting in crystal nuclei formation. The crystal nuclei were transformed to scorodite by oxidation with a supply of solute [Fe(III)] from the solution and ostwald ripening. Clustered scorodite (4 um in size) was obtained via synthesis using 200 kHz ultrasound (pH 0.5). Arsenic could be separated from the clustered scorodite via alkaline treatment; scorodite was changed to porous g-Fe2O3 comprising nanosized particles. Porous g-Fe2O3 was evaluated as a cathode in a lithium-ion battery, which showed a 149 mAh g[?]1 discharge capacity with a 0.5 C rate.

Published
2019

249. Synthesis of ZnxCd1-xS Solid Solution by Stratified Method.

Author

Arai, Takeo, Nakazato, Makoto, Shinoda, Kozo, Jeyadevan, Balachandran, and Tohji, Kazuyuki

Subjects
*PHOTOCATALYSIS, *CATALYSIS, *SOLID solutions, *CRYSTALLIZATION, *HYDROGEN sulfide, *POISONOUS gases, *PHYSICS
Abstract

In this study, we focused our attention on photocatalytic decomposition of hydrogen sulfide as the resource of hydrogen using solar energy and prepared ZnxCd1-xS solid solution as photocatalyst. Samples were prepared by “stratified” method using Zn and Cd hydroxides as precursors and “coprecipitation” method under various Zn/ Cd ratios to study the influence of Cd concentration on the properties such as crystal structure, light absorption and reactivity. The continuous change in the crystal lattice constant and UV-VIS reflection spectra from ZnS to CdS was observed in the ZnxCd1-xS samples prepared by both “coprecipitation” and “stratified” methods with increasing concentration of Cd. In the case of coprecipitation method, the reactivity was improved with the increase of Cd. But, in the case of stratified method, the particles prepared at Zn:Cd=2:1 showed higher reactivity than the samples prepared at higher ratios of Cd and the samples prepared by coprecipitation method with similar Zn/Cd ratios. The samples prepared by stratified method at higher ratio of Zn/Cd turned black from yellow in color when exposed to light irradiation. This was believed due to the metal deposited by photocatalytic reduction of precursors. This metal deposition influences the photoreactivity of ZnxCd1-xS particles and is optimum for Zn0.67Cd0.33S. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

Published
2006
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250. Structural Study of Poly-Molybdate Ions in Acid Mo-Ni Aqueuous Solutions

Author

Matsubara, Eiichiro and Shinoda, Kozo

Abstract

Structures of poly-molybdate ions in acid Ni-Mo aqueous solutions have been investigated by the anomalous x-ray scattering (AXS), EXAFS and small angle x-ray scattering (SAXS) methods. In a solution containing only molybdenum ions, molybdenum ions form a poly-molybdate ion consisting of seven edge-sharing MoO6octahedra. In a solution containing both Mo and Ni ions, there exists another poly-molybdate ion consisting of 6 edge-sharing MoO6surrounding a Ni ion. The coordination number of Mo-Mo pairs decreases by half by adding citric ions. This indicates that the large poly-molybdate ion is decomposed to smaller molybdate ions due to formation of citric complexes. This is also confirmed by the SAXS measurement. Since molybdenum-nickel alloys are not electrodeposited from the solutions without citric ions, we expect that the decomposition of large poly-molybdate ions in the solution is closely related with the mechanism of the induced codeposition of molybdenum and nickel alloy.

Published
1999
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