Fe-containing mesoporous silicates with macro-lamellar morphology

Fe-containing mesoporous silicates with macro-lamellar morphology were prepared using sodium silicates and Fe(NO3)(3) as silica and iron sources in alkaline media, respectively, under the direction of CTAB cationic surfactant. XRD and N-2 adsorption results showed that the sample had highly ordered hexagonal mesostructures typical of MCM-41. UV-vis and ESR spectra indicated that most of the iron species were tetrahedrally incorporated into the mesostructured framework in alkaline media. TEM micrographs manifested the macro-lamellar structures when the SiO2/Fe2O3 = 60 (molar ratio). Additionally, there were many submicron-sized structural defect voids in the mesostructured lamellas. The morphology character underwent huge changes with the increase of Fe(NO3)(3) amounts in the synthesis media. When the SiO2/Fe2O3 = 40, tangled microtubules with about several microns in length dominated the final product. Decreasing the SiO2/Fe2O3 molar ratio to 20, the long cylinders disappeared and 100-600 nm sticks represented 80% of the solid material. The dimensions of the resultant sample were reduced with the decrease of SiO2/Fe2O3 molar ratio. The formation mechanism of the macro-lamellar morphology was also proposed on the basis of the previous reports and our characterization results. (c) 2007 Elsevier Inc. All rights reserved.