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タイトル: | Proton-Enhanced Dielectric Properties of Polyoxometalates in Water under Radio-Frequency Electromagnetic Waves |
著者: | Tsubaki, Shuntaro Hayakawa, Shogo Ueda, Tadaharu Mitani, Tomohiko https://orcid.org/0000-0002-8544-2558 (unconfirmed) Suzuki, Ei-ichi Fujii, Satoshi Wada, Yuji |
著者名の別形: | 三谷, 友彦 |
キーワード: | polyoxometalate dielectric spectroscopy radio frequency proton relay |
発行日: | Jul-2018 |
出版者: | MDPI AG |
誌名: | Materials |
巻: | 11 |
号: | 7 |
論文番号: | 1202 |
抄録: | Electromagnetic waves, such as microwaves, have been used to enhance various chemical reactions over polyoxometalates. The dielectric properties of catalysts are among the relevant parameters facilitating catalytic reactions under electromagnetic radiation. This study describes the dielectric properties of polyoxometalate catalysts in aqueous and organic solutions to understand the mechanism of interactions between polyoxometalates and electromagnetic waves. Specific loss factors of polyoxometalates were observed at lower frequencies (<1 GHz) by the ionic conduction of the polyoxometalate solution. The evolution of ionic conduction depended strongly on cations rather than anions. Proton-type polyoxometalates exhibited significantly higher loss factors than other cations did. The activation energy for ionic conduction in protonated silicotungstic acid (H₄SiW₁₂O₄₀) was significantly low in water (7.6–14.1 kJ/mol); therefore, the high loss factor of protonated polyoxometalates in water was attributed to the proton relay mechanism (i.e., Grotthuss mechanism). The results suggested that the proton relay mechanism at the radio-frequency band is critical for generating selective interactions of polyoxometalates with applied electromagnetic fields. |
著作権等: | © 2018 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/). |
URI: | http://hdl.handle.net/2433/236476 |
DOI(出版社版): | 10.3390/ma11071202 |
PubMed ID: | 30011791 |
出現コレクション: | 学術雑誌掲載論文等 |
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