Size-Controlled Synthesis of Anatase in a Mesoporous Silica, SBA-15

Abstract

The preparation of anatase in the cylindrical mesopore of SBA-15 (pore size of 8 nm) was done by the impregnation of tetraisopropyl orthotitanate and its subsequent crystallization. The impregnation was done without a solvent. Hydrolysis and condensation were promoted by the HCl vapor to encapsulate a larger amount of titanium oxo species in the mesopore and to suppress the desorption of the titanium oxo species during crystallization to anatase. After the reaction, the shape of the N adsorption isotherm changed significantly, indicating the decrease of the Brunauer-Emmett-Teller surface area from 743 to 283 m/g and of the pore volume from 1.27 to 0.26 cm/g, respectively. After the crystallization to anatase, the TiO content in the product was estimated to be 62 mass %, filling 30% of the pore volume of SBA-15. The homogeneous distribution of titanium in the SBA-15 sample was confirmed by elemental mapping based on scanning electron microscopy/energy-dispersive X-ray spectrometry. The crystal size of the anatase was determined to be ca. 8.1 nm, which is consistent with the pore size of the used SBA-15 (8.0 nm, derived from the Barrett-Joyner-Halenda analysis of the nitrogen adsorption isotherm). The zeta potential measurements showed the absence of anatase as isolated particles or on the surface of SBA-15 particles. All of these characterizations confirmed the successful size-controlled synthesis of anatase in the mesopore of SBA-15.

Crystallization of well-defined anatase nanoparticles in SBA-15 for the photocatalytic decomposition of acetic acid

“…In the present study, thanks the well-dened porous structure of a mesoporous silica, the exclusive immobilization as well as the regular special distribution/isolation of the anatase particles in the mesopore, 23,24 the size of the anatase particles was maintained keeping the narrow particle size distribution and the porosity of the hybrid was also kept for the crystallization of anatase from 200 to 600 C. The crystallization of the anatase in the pores of mesoporous silicas with varied compositions and mesostructures are worth investigating to understand the role of the embedded TiO 2 on the stability of the mesostructure and the role of mesoporous silica on the crystallization and phase transformation of the embedded TiO 2 .…”

“…The value was consistent with the decrease of pore volume (30% of pore volume), derived from the pore volume of SBA-15 (1.0 cm 3 g À1 of silica) and SBA-15-anatase-600 (0.7 cm 3 g À1 of silica), which suggested the formation of the anatase in the mesopores. 23 As shown in the SEM images ( Fig. 2), no change in the particle morphology of the SBA-15 was seen aer the immobilization of TiO 2 and the heat treatment at 600 C and no anatase particles were observed in the external surface of the SBA-15-anatase particles.…”

“…The incorporation of anatase in the mesopore of SBA-15 is based on the preferential impregnation of TTIP into the pore and subsequent heat treatment as reported previously. 23,24 TTIP was mixed with IPA and the mixture was sonicated for 15 min by to obtain the homogenous transparent solution. The volume ratio of TTIP:IPA was designed as 1 : 8 to keep the remaining pore space aer the removal of IPA aer the heat treatment.…”

Pore shape-reflecting morphosynthesis of lithium niobium oxide via mixed chloride flux growth in the presence of mesoporous silica

“…[7][8][9][10][11][12][13][14] The rigid, uniform, and size-and shape-tunable nanopores of mesoporous materials, including mesoporous silica, have oen been utilized; 4,10,11 precursors are adsorbed/deposited onto the pores from solution or through vapors, and sequentially converted into inorganic nanoparticles by post-treatment such as calcination. This method using a periodic porous material as a "template" provides nanoparticles with morphologies that reect the pore size and shape; these may be nanoparticles, 8,[15][16][17][18] including nanowires, 15,[19][20][21][22][23][24] or inverse replicas, including mesoporous carbons. 25,26 Flux growth is a well-known simple procedure for obtaining idiomorphic crystals with high crystallinity.…”

Electron Microscopy Study of TiO2 Nanoparticle in Mesoporous Silica

“…Titania nanoparticles were immobilized preferentially into the 8 nm diameter pores of a mesoporous silica, SBA-15, by the impregnation of tetraisopropyl orthotitanate (TTIP) as a TiO2 precursor [2]. The size of TiO2 particles was controlled by varying the titania loading, which was achieved by diluting TTIP with isopropanol.…”