Issue 39, 2018

A vesicle-aggregation-assembly approach to highly ordered mesoporous γ-alumina microspheres with shifted double-diamond networks

Abstract

Alumina materials have widely been used in industrial fields, such as catalysis and adsorption. However, due to the fast sol–gel process and complicated crystalline-phase transformation, the synthesis of alumina materials with both highly ordered mesostructures and crystallized frameworks remains a great challenge. Herein, we report a novel vesicle-aggregation-assembly strategy to prepare highly ordered mesoporous γ-alumina microspheres with unique shifted double-diamond networks for the first time, by using diblock copolymer poly(ethylene oxide)-b-poly(methyl methacrylate) (PEO-b-PMMA) as a template and aluminum isopropoxide as a precursor in a tetrahydrofuran (THF)/hydrochloric acid binary solvent. During the gradual evaporation of THF and H2O, the as-made Al3+-based gel/PEO-b-PMMA composites can be obtained through a co-assembly process based on the hydrogen bonding interaction between hydroxyl groups of alumina oligomers and PEO segments of the diblock copolymers. The formed composites exhibit a spherical morphology with a wide size distribution (diameter size 1–12 μm). Furthermore, these composite microspheres possess an inverse bicontinuous cubic mesostructure (double diamond, Pn[3 with combining macron]m) with Al3+-based gel buried in the PEO-b-PMMA matrix in the form of two intertwined but disconnected networks. After a simple calcination at 900 °C in air, the structure of the resultant mesoporous alumina changes to a relatively low symmetry (shifted double diamond, Fd[3 with combining macron]m), ascribed to the shifting of the two alumina networks due to loss of the templates. Meanwhile, the unit cell size of the alumina mesostructure decreases from ∼131 to ∼95 nm. The obtained ordered mesoporous alumina products retain the spherical morphology and possess ultra-large mesopores (∼72.8 nm), columnar frameworks composed of γ-alumina nanocrystalline particles (crystal size of ∼15 nm) and high thermal stability (up to 900 °C). As a support of Au nanoparticles, the formed Au/mesoporous γ-alumina composite catalysts have been used in the catalytic reduction of 4-nitrophenol with a high kinetic constant k of 0.0888 min−1, implying promising potential as a catalyst support.

Graphical abstract: A vesicle-aggregation-assembly approach to highly ordered mesoporous γ-alumina microspheres with shifted double-diamond networks

Supplementary files

Article information

Article type
Edge Article
Submitted
05 7 2018
Accepted
17 8 2018
First published
17 8 2018
This article is Open Access

All publication charges for this article have been paid for by the Royal Society of Chemistry
Creative Commons BY license

Chem. Sci., 2018,9, 7705-7714

A vesicle-aggregation-assembly approach to highly ordered mesoporous γ-alumina microspheres with shifted double-diamond networks

Y. Liu, W. Teng, G. Chen, Z. Zhao, W. Zhang, B. Kong, W. N. Hozzein, A. A. Al-Khalaf, Y. Deng and D. Zhao, Chem. Sci., 2018, 9, 7705 DOI: 10.1039/C8SC02967A

This article is licensed under a Creative Commons Attribution 3.0 Unported Licence. You can use material from this article in other publications without requesting further permissions from the RSC, provided that the correct acknowledgement is given.

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