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Titre
Temperature dependence of dc electrical conductivity of activated carbon–metal oxide nanocomposites. Some insight into conduction mechanisms
Autor(es)
Sujet
Microporous materials
Semiconductors
Chemical synthesis
Electrical conductivity
Electronic structure
Clasificación UNESCO
2211.20 Conductores Metálicos
2303 Química Inorgánica
Fecha de publicación
2015
Éditeur
Elsevier
Citación
Barroso-Bogeat, A., Alexandre-Franco, M., Fernández-González, C., Sánchez-González, J., Gómez-Serrano, V. (2015). Temperature dependence of dc electrical conductivity of activated carbon-metal oxide nanocomposites. Some insight into conduction mechanisms, Journal of Physics and Chemistry of Solids, 87. pp 259-270. http://dx.doi.org/10.1016/j.jpcs.2015.08.021
Resumen
[EN] From a commercial activated carbon (AC) and six metal oxide (Al2O3, Fe2O3, SnO2, TiO2, WO3 and ZnO)
precursors, two series of AC–metal oxide nanocomposites are prepared by wet impregnation, ovendrying at 120 °C, and subsequent heat treatment at 200 or 850 °C in inert atmosphere. The temperaturedependent dc electrical conductivity of AC and the as-prepared nanocomposites is measured from room
temperature up to ca. 200 °C in air atmosphere by the four-probe method. The decrease in conductivity
for the hybrid materials as compared to AC is the result of a complex interplay between several factors,
including not only the intrinsic conductivity, crystallite size, content and chemical nature of the supported nanoparticles, which ultimately depend on the precursor and heat treatment temperature, but
also the adsorption of oxygen and water from the surrounding atmosphere. The conductivity data are
discussed in terms of a thermally activated process. In this regard, both AC and the prepared nanocomposites behave as semiconductors, and the temperature-dependent conductivity data have been
interpreted on the basis of the classical model proposed by Mott and Davis. Because of its high content of
heteroatoms, AC may be considered as a heavily doped semiconductor, so that conduction of thermally
excited carriers via acceptor or donor levels is expected to be the dominant mechanism. The activation
energies for the hybrid materials suggest that the supported metal oxide nanoparticles strongly modify
the electronic band structure of AC by introducing new trap levels in different positions along its band
gap. Furthermore, the thermally activated conduction process satisfies the Meyer–Neldel rule, which is
likely connected with the shift of the Fermi level due to the introduction of the different metal oxide
nanoparticles in the AC matrix.
URI
ISSN
0022-3697
DOI
10.1016/j.jpcs.2015.08.021
Versión del editor
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