Reitz, Christian and Suchomski, Christian and Weidmann, Christoph and Brezesinski, Torsten (2011) Block copolymer-templated BiFeO3 nanoarchitectures composed of phase-pure crystallites intermingled with a continuous mesoporosity: Effective visible-light photocatalysts? Nano Research, 4 (4). pp. 414-424. ISSN 1998-0124 (Print) 1998-0000 (Online)
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Official URL: http://www.springerlink.com/content/j242238l477237...
Herein is reported the soft-templating synthesis of visible-light photoactive bismuth ferrite (BiFeO3) nanoarchitectures in the form of thin films using a poly(ethylene-co-butylene)-block-poly(ethylene oxide) diblock copolymer as the structure-directing agent. We establish that (1) the self-assembled materials employed in this work are highly crystalline after annealing at 550 Â°C in air and that (2) neither the bismuth-poor Bi2Fe4O9 phase nor other impurity phases are formed. We further show that there is a distinct restructuring of the high quality cubic pore network of amorphous BiFeO3 during crystallization. This restructuring leads to films with a unique architecture that is composed of anisotropic crystallites intermingled with a continuous mesoporosity. While this article focuses on the characterization of these novel materials by electron microscopy, krypton physisorption, grazing incidence small-angle X-ray scattering, time-of-flight secondary ion mass spectrometry, X-ray photoelectron spectroscopy, UV-vis and Raman spectroscopy, we also examine the photocatalytic properties and show the benefits of the combination of mesoporosity and nanocrystallinity. Templated BiFeO3 thin films (25% porosity) with a direct optical band gap at 2.9 eV exhibit a catalytic activity for the degradation of rhodamine B much better than that of nontemplated samples. We attribute this improvement to the nanoscale porosity, which provides for more available active sites on the photocatalyst.
|Subjects:||Material Science > Functional and hybrid materials|
Material Science > Nanofabrication processes and tools
|Deposited By:||M T V|
|Deposited On:||09 May 2011 10:25|
|Last Modified:||09 May 2011 10:25|
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