Anatase TiO2 crystal facet growth: Mechanistic role of hydrofluoric acid and photoelectrocatalytic activity

Zhang, Haimin, Wang, Yun, Liu, Porun, Han, Yanhe, Yao, Xiangdong, Zou, Jin, Cheng, Huiming and Zhao, Huijun (2011) Anatase TiO2 crystal facet growth: Mechanistic role of hydrofluoric acid and photoelectrocatalytic activity. ACS Applied Materials and Interfaces, 3 7: 2472-2478.


Author Zhang, Haimin
Wang, Yun
Liu, Porun
Han, Yanhe
Yao, Xiangdong
Zou, Jin
Cheng, Huiming
Zhao, Huijun
Title Anatase TiO2 crystal facet growth: Mechanistic role of hydrofluoric acid and photoelectrocatalytic activity
Formatted title Anatase TiO2 crystal facet growth: Mechanistic role of hydrofluoric acid and photoelectrocatalytic activity
Journal name ACS Applied Materials and Interfaces   Check publisher's open access policy
ISSN 1944-8244
1944-8252
Publication date 2011-07-27
Sub-type Article (original research)
DOI 10.1021/am200363p
Volume 3
Issue 7
Start page 2472
End page 2478
Total pages 7
Place of publication Washington, DC, U.S.A.
Publisher American Chemical Society
Collection year 2012
Language eng
Formatted abstract This work reports a facile hydrothermal approach to directly grow anatase TiO2 crystals with exposed {001} facets on titanium foil substrate by controlling pH of HF solution. The mechanistic role of HF for control growth of the crystal facet of anatase TiO2 crystals has been investigated. The results demonstrate that controlling solution pH controls the extent of surface fluorination of anatase TiO2, hence the size, shape, morphology, and {001} faceted surface area of TiO2 crystals. The theoretical calculations reveal that {001} faceted surface fluorination of anatase TiO2 can merely occur via dissociative adsorption of HF molecules under acidic conditions while the adsorption of Na+F is thermodynamically prohibited. This confirms that the presence of molecular form of HF but not F is essential for preservation of exposed {001} facets of anatase TiO2. Anatase TiO2 crystals with exposed {001} facets can be directly fabricated on titanium foil by controlling the solution pH ≤ 5.8. When pH is increased to near neutral and beyond (e.g., pH ≥ 6.6), the insufficient concentration of HF ([HF] ≤ 0.04%) dramatically reduces the extent of surface fluorination, leading to the formation of anatase TiO2 crystals with {101} facets and titanate nanorods/nanosheets. The anatase TiO2 nanocrystals with exposed {001} facets exhibits a superior photoelectrocatalytic activity toward water oxidation. The findings of this work clarify the mechanistic role of HF for controlling the crystal facet growth, providing a facile means for massive production of desired nanostructures with high reactive facets on solid substrates for other metal oxides.
Keyword Anatase TiO2
Microspheres
Nanocrystals
{001} Facets
Photoelectrocatalysis
Exposed 001 facets
Photocatalytic degradation
Surface fluorination
Nanotube arrays
Film electrodes
Visible-light
Nanosheets
Percentage
Microspheres
Fabrication
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ

 
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