Multilayered SiO₂/TiO₂ Nanosol Particles in Two-Dimensional Aluminosilicate Catalyst−Support

Abstract

A new layered nanocomposite, which is one-to-one interstratified with a montmorillonite layer and a mixed SiO 2 /TiO 2 sol particle one, has been prepared by ion exchange reaction of the Na + ion in montmorillonite with the positively charged SiO 2 /TiO 2 sol particles. The ion exchange reaction was performed at three different temperatures of 45, 60, and 75°C by mixing an aqueous suspension of 1 wt % Na + montmorillonite with SiO 2 /TiO 2 sol solution where the molar ratio of Si/Ti was selected as 20/2. According to the powder X-ray diffraction analysis, the basal spacings of layered nanocomposites calcined at 400°C were found to increase from 35.4 Å, to 47.3 Å, and to 60.0 Å as the ion exchange reaction temperature was raised from 40°C, to 60°C, and to 75°C. Their BET and Langmuir specific surface areas and porosities, estimated from nitrogen adsorption-desorption isotherms, become larger with the increment of basal spacing, and the highest BET specific surface area and the largest porosity are found to be 683 m 2 /g and 0.50 mL/g, respectively. Despite the large increment of the basal spacing, the porous properties such as specific surface areas, porosities, and pore sizes, those which are calculated from t-plots and chemical shift of 129 Xe NMR, respectively, are determined to be almost constant. From the UV/vis spectra, the blue shift of the absorption edge was observed, indicating that the TiO 2 sol particles in the interlayer are quantum sized. It is therefore proposed that the products are intercalation-type nanocomposites with the multistacked structure of the SiO 2 /TiO 2 nanoparticles in the interlayer space of montmorillonite.

Synthesis of silver nanoparticles in montmorillonite and their antibacterial behavior

“…The silver nanoparticles (Ag NPs) deposited on inorganic substrates, such as TiO 2 10 and phyllosilicates such as MMT, [11][12][13] kaolinite, 14 and synthetic layered silicate such as laponite, 15 have also been used as carriers for Ag/nanocomposites. For the synthesis of Ag NPs in the solid substrate, AgNO 3 is often used as the primary source of Ag + .…”

“…1 To overcome agglomeration, preparation of nanoparticles based on clay compounds, in which nanoparticles are supported within the interlamellar spaces of clay and/or on its external surfaces, is one of the most effective solutions. [2][3][4] Synthesis of metal nanoparticles on solid supports such as smectite clays is a suitable way to prepare practically applicable supported particles as well as to control the particle size. Smectite clays have excellent swelling and adsorption ability, which is especially interesting for the impregnation of antibacterial-active nano-size metals in the interlamellar space of clay.…”

Synthesis and characterization of silver/talc nanocomposites using the wet chemical reduction method

“…7 To overcome agglomeration, preparation of nanoparticles based on clay compounds, in which nanoparticles are supported within the interlamellar spaces of clay and/or on the external surfaces, is one of the most effective solutions. [8][9][10] Synthesis of nanoparticle/ clay composites is very important in the fabrication of such different tools as optical devices, adsorbents, catalysts, sensors, polarizers, color filters, magnetic data storage media, and many others. [11][12][13][14][15][16][17][18] The main characteristics of these nanocomposites are the size and shape of the incorporated metal nanoparticles, as well as the chemical and physical properties of the clay source (ie, ion absorption capacity, active surface area, and interlamellar space).…”

External-Field Hot-Water Treatments of Sol-Gel Derived SiO2-TiO2 Coatings for Surface Nanostructure Control-A Review-

“…[4][5][6][7][8][9][10][11][12] The control of the nanostructures of the titania-based coatings further offers an exciting opportunity to enhance their unique physical and chemical properties. The performance of their photocatalytic reactions depends on the characteristics of the titania cryatallites, such as the size and surface area.…”