Synthesis of Mesoporous Ceria by Using CTAB as Template
S. E. Borjas-García
1
, A. Medina-Flores
2
, L. Béjar
2
, P. Martínez-Torres
1
, N. Dasgupta-Schubert
3
, J. L.
Bernal
4
1
Instituto de Física y Matemáticas, Universidad Michoacana de San Nicolás de Hidalgo, Morelia,
Michoacán, México
2
Instituto de Investigaciones Metalúrgicas, Universidad Michoacana de San Nicolás de Hidalgo,
Morelia, Michoacán, México
3
Instituto de Investigaciones Químico-Biológicas, Universidad Michoacana de San Nicolás de Hidalgo,
Morelia, Michoacán, México
4
Automotive Mechanics Department. Universidad Politécnica de Pachuca. Zempoala, Hidalgo. México
A material which contains pores in a range between 2 and 50 nm is considered as mesoporous material
[1]. The first publication about the synthesis of this kind of material by using an organic template was in
1992 by Mobil scientist [2]. In the case of the synthesis method of mesoporous ceria, different organic
templates have been used; for example, cetyltrimethylammonium bromide (CTAB) [3] and triblock
copolymer non ionic surfactant [4-6]. However, there is not enough research about the synthesis of
mesoporous ceria by using CTAB as template. Mesoporous ceria was synthesized using both Sol – Gel
method with a hydrothermal soft treatment. The mesopores of ceria was prepared by using cerium
chloride heptahydrate (Sigma-Aldrich), Sodium hydroxide (J.T.Baker) and hexadecyltrimethyl
ammonium bromide, CTAB (Sigma, purity) as source, alkaline material and template, respectively. In a
first step, two solutions were prepared. The first one was obtained by dissolving 1.863 g of CeCl
3
*7H
2
O
and 0.911 of CTAB in 20 g of distilled water. For the second solution, 1.6 g of NaOH was dissolved in
10 g of distilled water. In a second step, the Na-solution was added slowly (drop by drop) to Ce-solution
and stirred. The final solution was stirred and heat in a hot stir plate at 90 °C to get a material with a
molar ratio of CeCl
3
*7H
2
O:CTAB:NaOH:H
2
O equal to 1:0.5:8:150. The gel obtained was aged in a
polypropylene bottle at 80 °C for 1 day. After the hydrothermal treatment, the sample was washed with
100 ml of distilled water and centrifuged at 12000 rpm. After that, the material was dried at 80 °C for 1
day. After the synthesis procedure showed above, the calcination of the sample is necessary at 560 °C
for 6 hrs in order to obtain complete formation of cerium oxide and complete elimination of organic
template. The surface morphology and the structural characteristics images of the as-synthesized
samples were analyzed by using a scanning electron microscopy FEG-SEM JEOL JSM 7600 and a
Tecnai F20 microscope with a field emission gun, respectively. Figure 1a shows an SEM image of ceria
synthesized. This figure shows particle size in nanometric scale (<100 nm). Figure 1b shows the EDS
spectrum taken over material analyzed. Figure 2 shows the presence of mesopores in the material with a
pore size > 2 nm. In this case, the results showed that the molar ratio between cerium and CTAB and
hydrothermal treatment temperature could be critical parameters in the formation of mesoporous ceria.
Also, medium amount of water in the synthesis procedure allow the formation of mesopores in the
material. The synthesis procedure of ceria presented in this research work is easy with a low cost.
References
[1] D.W. Bruce, D. O´Hare and R.I. Walton, “Porous materials”, 1st ed. (Wiley, United Kingdom, 2010)
p. 1.
[2] C. T. Kresge et al, Nature Volume 359 (1992) p. 710.
1918
doi:10.1017/S1431927616010436
Microsc. Microanal. 22 (Suppl 3), 2016
© Microscopy Society of America 2016