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

Paper ID Volume ID Publish Year Pages File Format Full-Text
54286 47004 2014 9 PDF Available
Title
Polymer-templated ordered large-pore mesoporous anatase–rutile TiO2:Ta nanocomposite films: Microstructure, electrical conductivity, and photocatalytic and photoelectrochemical properties
Abstract

•Truly large-pore mesoporous anatase–rutile TiO2:Ta films were synthesized through swelling agent-free polymer templating.•The in-plane pore size can be readily tailored from 17 nm to 26 nm through the choice of polymer structure-directing agent.•Both the pore structure and phase composition (∼20% rutile and 80% anatase) are little affected up to temperatures of 800 °C.•The electrical conductivity is significantly increased compared to bulk forms of highly stoichiometric TiO2.•Mesoporous anatase–rutile TiO2:Ta films show promise for application in the forefront field of environmental catalysis.

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 (SBET ≥ 150 m2 g−1). 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 °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 °C, and that (5) the films contain a non-negligible fraction of Ti3+ species. The latter results in a room-temperature electrical conductivity (∼2.4 mS cm−1) much higher than that reported for stoichiometric TiO2. Compositionally, the material can be described by the chemical formula Ta0.24Ti0.75O2±δ. The mesoporous nanocomposite films (Eg ≈ 3.4 eV) also display interesting photocatalytic properties and photoelectrochemical activity which makes them interesting for different applications such as wastewater detoxification.

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Keywords
Anatase; Rutile; Mesoporous; Electrical conductivity; Photocatalysis; Water splitting
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Polymer-templated ordered large-pore mesoporous anatase–rutile TiO2:Ta nanocomposite films: Microstructure, electrical conductivity, and photocatalytic and photoelectrochemical properties
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Publisher
Database: Elsevier - ScienceDirect
Journal: Catalysis Today - Volume 225, 15 April 2014, Pages 55–63
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Catalysis
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Don't Miss Today's Special Offer
Price was $35.95
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Price after discount Only $4.95
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