Thermally Stable Nanoporous Nanocrystalline TiO₂ with a Bicrystalline (Anatase-Brookite) Framework Fabricated via Combining the Soft-Templating with Solid-Liquid Method

Abstract

Mesoporous anatase-brookite nanocrystalline titania was synthesized via a novel strategy relying on the combination of soft-templating and solid-liquid method (CSSL), in which the mesostructured titania hybrid was firstly synthesized via cooperative assembly between titanium sulphate and 1-hexadecyl-3-methylimidazolium bromide (C₁₆mim⁺Br⁻), and subsequently ground with solid magnesium nitrate salt followed by heat-treatment in air. The resulting mesoporous titania material still possessed a large surface area of 150 m²/g even at 700°C of calcination temperature. The anatase phase in the titania framework transformed to brookite phase at 600°C. Moreover, the photocatalytic activities of as-synthesized titania materials in the degradation of methylene orange under ultraviolet irradiation were found to be determined by their surface areas and brookite phase contents.

Keywords:

• Mesoporous
• mixed phase
• thermally stable
• titania

Acknowledgments

This research was financially supported by the Key Project Foundation of the Ministry of Education of China (No. 105104), the Natural Science Foundation of China (No. 50572057), the Middle-Aged and Youthful Excellent Scientist Encouragement Foundation of Shandong (No. 2005BS11003), the Natural Science Foundation of Shandong Province (No. Z2006B02), and the Scientific and Technological Development Project of Shandong Province (No. 2007GG20006002).

Notes

^a Calculated by the Scherrer formula.

^b Calculated using the formula in ref.^{[ 32 ]}

^c BET surface area calculated from the linear part of the BET plot (P/P₀ = 0.05–0.3).

^d Most probable pore diameter calculated from the desorption branch using the Barrett-Joyner-Halenda (BJH) method.

^e Total pore volume at P/P₀ = 0.97.

^f Photodegradation reaction rate constant.