Photochromogenic Nanosheet Crystallites of Tungstate with a 2D Bronze Structure

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• 作者：Katsutoshi Fukuda ; Kosho Akatsuka ; Yasuo Ebina ; Minoru Osada ; Wataru Sugimoto ; Mutsumi Kimura ; Takayoshi Sasaki
• 刊名：Inorganic Chemistry
• 出版年：2012
• 出版时间：February 6, 2012
• 年：2012
• 卷：51
• 期：3
• 页码：1540-1543
• 全文大小：268K
• 年卷期：v.51,no.3(February 6, 2012)
• ISSN：1520-510X

文摘

Layered rubidium tungstate, Rb₄W₁₁O₃₅, with a two-dimensional (2D) bronze-type tunnel structure was successfully delaminated into colloidal nanosheets via a soft-chemical process involving acid exchange and subsequent intercalation of tetrabutylammonium ions. Characterizations by transmission electron microscopy and atomic force microscopy confirmed the formation of unilamellar 2D nanosheet crystallites with a unique thickness of 3 nm and an average lateral size of 400 nm. The obtained nanosheets exhibited reversible color change upon UV-light excitation via an optical band gap of 3.5 eV. The ultimate 2D aspect ratio favorable for an adsorption of charge-compensating cations to trapped electrons working as a color center is presumably responsible for highly efficient photochromic behavior. Its coloration mainly consists of a broad band at a wavelength of 1800 nm and longer, which is much different from that of the common tungstate nanomaterials. Thus, the chromogenic nanosheet obtained in this study features the intense UV absorption and optically switchable visible-to-IR absorption, which may be useful for window applications such as cutoff filters and heat-absorbing films.