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Formation of mesoporous Co3O4 replicas of different mesostructureswith different pore sizes
Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry. (Osamu Terasaki)
2009 (English)In: Microporous and Mesoporous Materials, ISSN 1387-1811, Vol. 123, 314-323 p.Article in journal (Refereed) Published
Abstract [en]

Mesoporous metal oxides Co3O4 are prepared via hard templating synthesis method by using various mesoporous silicas with different pore size as templates. The pore size of the mesoporous silicas with the symmetry of two-dimensional (2d)-hexagonal p6mm, bicontinuous cubic Ia-3d and Pn-3m have been controlled in the range of 6.6–10.7, 4.2–7.5 and 5.1–6.7 nm, respectively, by choosing different surfactants and co-surfactants and by adjusting either the aging temperature or the ionization degree of the surfactant. The pore size of the silica template has been considered to be an important factor that determines the mesostructure of the resulting metal oxides. It has been found that for p6mm, it is easier to replicate the mesoporous symmetry at large size of mesopores. For Ia-3d, at large-pore size two sets of bicontinuous meso-channels are replicated into mesoporous Co3O4, while small-pore Ia-3d leads to replication of both one set and two sets of meso-channels. Co3O4 can replicate both one set and two sets of bicontinuous Pn-3m meso-channels at all pore sizes that can be obtained (5.1–6.7 nm), indicating the existence of ordered complementary micropores within the silica walls.

Place, publisher, year, edition, pages
Elsevier , 2009. Vol. 123, 314-323 p.
Keyword [en]
mesoporous cobalt oxide, hard templating, replica, mesostructure, pore size
Research subject
Materials Science
URN: urn:nbn:se:su:diva-29617DOI: 10.1016/j.micromeso.2009.04.017ISI: 000267099000039OAI: diva2:234487
Available from: 2009-09-09 Created: 2009-09-08 Last updated: 2009-09-09Bibliographically approved
In thesis
1. Formation mechanism of anionic-surfactant-templated mesoporous silica (AMS)
Open this publication in new window or tab >>Formation mechanism of anionic-surfactant-templated mesoporous silica (AMS)
2009 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This dissertation is focused on synthesis, characterization and formation mechanism of anionic-surfactant-templated mesoporous silica (AMS).

Structural control mechanisms of AMS are investigated. First, different ionization degree of anionic surfactant affected by the acidity or alkalinity of the synthesis system gives rise to different charging density of micelles and therefore determines the organic/inorganic interface curvature, producing mesophases from cage-type to cylindrical, bicontinuous and lamellar. Second, mesocage/mesocage electrostatic repulsive interaction affects the formation of cage-type mesostructure, which is derived from a full-scaled synthesis-field diagram of AMS. The mesocage/mesocage interaction changes with charge density of mesocages and gives rise to their different packing manners. Third, the structural properties of AMS materials could be tuned by molecular features of surfactant and co-structure-directing agent (CSDA).

The pore size of AMS is found to be controlled by alkyl chain length, ionization degree of surfactant and the CSDA/surfactant ratio. Alkyl chain length of surfactant determines size of micelles and thus mesopores. Larger ionization degrees of anionic surfactant give rise to smaller pore sizes due to thermodynamic coiling of alkyl chains of surfactant. The hydrophobic interactions between the pendant organic groups of CSDA on the silica wall and the hydrophobic core of the micelles drive a contraction of the mesopores.

A mesoporous silica with novel bicontinuous cubic Pn-3m structure has been prepared using a diprotic anionic surfactant. 3d-reconstruction of the structure shows that it is bicontinuous composed of an enantiomeric pair of 3d mesoporous networks that are interwoven with each other, divided by a D surface. Inverse replication suggests the possible presence of ordered complimentary micropores in the material.

Place, publisher, year, edition, pages
Stockholm: Department of Physical, Inorganic and Structural Chemistry, Stockholm University, 2009. 75 p.
mesoporous silica, anionic surfactant, formation mechanism, structural control
National Category
Other Basic Medicine
Research subject
Structural Chemistry
urn:nbn:se:su:diva-29628 (URN)978-91-7155-932-6 (ISBN)
Public defence
2009-10-06, Magnélisalen, Kemiska övningslaboratoriet, Svante Arrhenius vägen 16 B, Stockholm, 13:30 (English)
Available from: 2009-09-15 Created: 2009-09-08 Last updated: 2009-09-15Bibliographically approved

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