Polymer-templated ordered large-pore mesoporous anatase-rutile TiO₂:Ta nanocomposite films: Microstructure, electrical conductivity, and photocatalytic and photoelectrochemical properties

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• 作者：Christian Reitz ; Jochen Reinacher ; Pascal Hartmann ; Torsten Brezesinski
• 关键词：Anatase ; Rutile ; Mesoporous ; Electrical conductivity ; Photocatalysis ; Water splitting
• 刊名：Catalysis Today
• 出版年：15 April, 2014
• 年：2014
• 卷：225
• 期：Complete
• 页码：55-63
• 全文大小：3215 K

文摘

We describe the polymer templating of inorganic sol-gel precursors for making thermally stable mesoporous anatase-rutile TiO₂:Ta nanocomposite films with high surface area (S_BET 鈮?#xA0;150 m² g^鈭?). Mesostructured films with cubic pore symmetry and pore sizes ranging from 17 nm to 26 nm in diameter were prepared from different diblock copolymers such as polyisobutylene-block-poly(ethylene oxide) and were characterized by various microscopy techniques, grazing incidence small-angle X-ray scattering, X-ray diffraction and Rietveld refinement, X-ray photoelectron spectroscopy, and impedance spectroscopy. Here, we specifically focus on the material with the smaller pores. Our research data establish that (1) the nanoscale structure can be preserved up to 900 掳C, (2) anatase is the primary phase, (3) the phase composition remains constant over a broad temperature range, (4) anatase-to-rutile transformation and formation of L-Ta₂O₅ do not occur below 800 掳C, and that (5) the films contain a non-negligible fraction of Ti³⁺ species. The latter results in a room-temperature electrical conductivity (鈭?.4 mS cm^鈭?) much higher than that reported for stoichiometric TiO₂. Compositionally, the material can be described by the chemical formula Ta_0.24Ti_0.75O_2卤未. The mesoporous nanocomposite films (E_g 鈮?#xA0;3.4 eV) also display interesting photocatalytic properties and photoelectrochemical activity which makes them interesting for different applications such as wastewater detoxification.