Hydrothermal stability of {001} faceted anatase TiO2

Yang, Xiao Hua, Li, Zhen, Sun, Cenghua, Yang, Hua Gui and Li, Chunzhong (2011) Hydrothermal stability of {001} faceted anatase TiO2. Chemistry of Materials, 23 15: 3486-3494. doi:10.1021/cm2008768


Author Yang, Xiao Hua
Li, Zhen
Sun, Cenghua
Yang, Hua Gui
Li, Chunzhong
Title Hydrothermal stability of {001} faceted anatase TiO2
Formatted title
Hydrothermal stability of {001} faceted anatase TiO2
Journal name Chemistry of Materials   Check publisher's open access policy
ISSN 0897-4756
1520-5002
Publication date 2011-08-01
Sub-type Article (original research)
DOI 10.1021/cm2008768
Open Access Status Not yet assessed
Volume 23
Issue 15
Start page 3486
End page 3494
Total pages 9
Place of publication Washington, DC, U.S.A.
Publisher American Chemical Society
Language eng
Subject 1600 Chemistry
1500 Chemical Engineering
2505 Materials Chemistry
Abstract Due to its great importance in fundamental research and practical applications, tailored synthesis of anatase TiO dominated with highly energetic {001} facets has been extensively studied during the past few years. However, clean (001) surface of anatase TiO has been evidenced to be unstable and usually tends to reconstruct under ultrahigh-vacuum conditions. Thus, the stability of surface structure under other ambient conditions might be one of the most critical issues for anatase TiO with exposed high-reactive {001} facets. In this study, the hydrothermal stability of {001} faceted anatase TiO was systematically investigated by using single-crystalline anatase TiO nanosheets with 80% {001} facets as a model starting material. Under hydrothermal conditions (200 °C in deionized water), anatase TiO nanosheets can grow into larger single crystals with a truncated bipyramidal shape through an oriented attachment process along the [001] crystallographic direction, driven by the minimization of surface energy. Furthermore, the coarsening behavior and growth mechanism were discussed with the assistance of standard and high-resolution transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and inductively coupled plasma optical emission spectrometry, as well as theoretical calculations. A modified kinetic model was also developed to elucidate the asymptotic growth of anatase TiO nanosheets via oriented attachment mechanism. In addition, pH value and the solvents adopted during the treatments were revealed to have significant influence on the oriented attachment-based crystal growth due to suppression of hydrolysis of Ti-F groups on the surface. For example, the anatase TiO nanosheets remained their original morphology unchanged when ethanol, propanol, butanol, or 1.5 M HCl aqueous solution was used as reaction medium.
Formatted abstract
Due to its great importance in fundamental research and practical applications, tailored synthesis of anatase TiO2 dominated with highly energetic {001} facets has been extensively studied during the past few years. However, clean (001) surface of anatase TiO2 has been evidenced to be unstable and usually tends to reconstruct under ultrahigh-vacuum conditions. Thus, the stability of surface structure under other ambient conditions might be one of the most critical issues for anatase TiO2 with exposed high-reactive {001} facets. In this study, the hydrothermal stability of {001} faceted anatase TiO2 was systematically investigated by using single-crystalline anatase TiO2 nanosheets with 80% {001} facets as a model starting material. Under hydrothermal conditions (200 °C in deionized water), anatase TiO2 nanosheets can grow into larger single crystals with a truncated bipyramidal shape through an oriented attachment process along the [001] crystallographic direction, driven by the minimization of surface energy. Furthermore, the coarsening behavior and growth mechanism were discussed with the assistance of standard and high-resolution transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and inductively coupled plasma optical emission spectrometry, as well as theoretical calculations. A modified kinetic model was also developed to elucidate the asymptotic growth of anatase TiO2 nanosheets via oriented attachment mechanism. In addition, pH value and the solvents adopted during the treatments were revealed to have significant influence on the oriented attachment-based crystal growth due to suppression of hydrolysis of Ti–F groups on the surface. For example, the anatase TiO2 nanosheets remained their original morphology unchanged when ethanol, propanol, butanol, or 1.5 M HCl aqueous solution was used as reaction medium.
Keyword Titanium dioxide
Nanosheets
Oriented attachment
Hydrothermal stability
High-reactive facets
High-Index Facets
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ

 
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