Title: The "cascade effect" of nano/micro hierarchical structure: A new concept for designing the high photoactivity materials - An example for TiO2
Authors: Chen, Po-Chin
Tsai, Min-Chiao
Yang, Min-Han
Chen, Ting-Ting
Chen, Huang-Chin
Chang, I. -Chun
Chang, Yi-Chun
Chen, Yu-Liang
Lin, I. -Nan
Chiu, Hsin-Tien
Lee, Chi-Young
Department of Applied Chemistry
Keywords: Titanium dioxide;Hierarchical structure;Photocatalyst;Charge separation;Hetero-junction
Issue Date: 1-Oct-2013
Abstract: The chrysanthemum-like TiO2 (CT800) was synthesized. It exhibited excellent photoactivity, which greatly exceeded that of conventional P25. To discover the key factors that governed the photocatalytic properties, the specific reduction of Ag+ ions was carried out and EPR spectra of CT800 were obtained. Both an HADDF image and EDX mapping indicated that the Ag+ ions tended to be reduced close to the center of the micro matrix of CT800. Moreover, the EPR spectra strongly suggest that the excited electrons tended to migrate toward the center of the micro matrix, resulting from a multiple junction, cascade effect, which efficiently reduces the recombination of excited electrons and holes and greatly increases the photoactivity. Additionally, the special morphology of CT800 was responsible for the hot spots at the surface of nano sheets and then contributing to its outstanding photocatalytic activity. Furthermore, the unidirectional electron transfer, because of the cascade effect, by materials of different sizes provides a new avenue for the design of electronic and photoelectrochemical devices. (c) 2013 Elsevier B.V. All rights reserved.
URI: http://dx.doi.org/10.1016/j.apcatb.2013.05.076
ISSN: 0926-3373
DOI: 10.1016/j.apcatb.2013.05.076
Volume: 142
Begin Page: 752
End Page: 760
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