Highly Dispersed Metal Nanoparticles in Functionalized SBA-15

Abstract

The preparation and characterization of highly dispersed metal nanoparticles in mesoporous silica SBA-15 are reported. The functionalization with organosilane to generate a monolayer of charged groups on the pore surface facilitates uniform distribution of ionexchanged metal precursors in the channels of SBA-15, which, upon reduction, results in highly dispersed metal nanoparticles supported in SBA-15. Under mild reduction conditions, the surface functionality remains and so allows further metal incorporation cycles to achieve higher metal loading. After reduction in hydrogen flow, disk-shaped Pt nanoparticles in Pt/ SBA-15 and spherical Au nanoparticles in Au/SBA-15 have been characterized in the channels of SBA-15 by PXRD, XAS, and TEM. Secondary Pt incorporation in Au/SBA-15 produces coexisting small Pt nanoparticles with large Au nanoparticles in the host channels. This preparation method is capable of template synthesis of various metal nanostructures with controlled morphology and composition inside the channels of mesoporous materials.

The modification of MoO3 nanoparticles supported on mesoporous SBA-15: characterization using X-ray scattering, N2 physisorption, transmission electron microscopy, high-angle annular darkfield technique, Raman and XAFS spectroscopy

“…For low loadings, the predominant silica-supported molybdenum species were observed to be isolated molybdate tetrahedra [21]. However, no bands at 988 and 620 cm -1 characteristic of MoO 4 2-were detected in our sample, indicating that MoO 3 should be formed as the majority species under our experimental conditions. At high loadings, the observed wave numbers for MoO 3 /SBA-15 materials are similar to that found for the physical mixture.…”

“…Such incorporated nanoparticles may have interesting optical, magnetic, and catalytic properties. In addition to the studies of the formation of metal nanoparticles and nanowires, such as Pt [3][4][5], Pd [6][7][8][9], Au [3-5, 10, 11], Ag [3], and Ti [12], the formation of binary nanomaterials such as PbS [13], CdS [14], TiN [15], and GaN [16] within the nanoscale channels of these mesoporous materials have been explored. More recently, highly ordered quantum wires of Zn 1-x Mn x S [17] and Cd 1-x Mn x S [18] have been successfully synthesized within the mesopores of SBA-15.…”

Synthesis of Gold Catalysts Supported on Mesoporous Silica Materials: Recent Developments

“…The preparation of dispersed AuNPs in mesoporous SBA-15 using TPTAC as functionalizing agent has been reported by Yang et al [41,58]. Gold was loaded on the functionalized SBA-15 using HAuCl 4 solution as precursor, and the slurry was chemically reduced with NaBH 4 aqueous solution.…”

“…The most used methods for preparing Au/MSM catalysts include the modification of the MSM support with organic functional groups by post-grafting or co-condensation before gold loading [41,42], one-pot synthesis by the incorporation of both gold and the coupling agent containing functional groups into the MSM synthesis [43], the use of cationic gold complexes such as [Au(en) 2 ]Cl 3 (en = ethylenediamine) [44], chemical vapor deposition using expensive organometallic gold precursors [45], synthesis of the MSM in the presence of gold colloids [46,47], dispersion of gold colloids protected by ligands or polymers onto SiO 2 [46,47], and modification of the mesoporous SiO 2 supports with other metal oxides, such as TiO 2 , Al 2 O 3 and CeO 2 to prepare SiO 2 -based gold catalysts [48,49].…”

Comparison of the synthesis routes for the ZnO/porous silica nanocomposite

“…A minor variation in the position and intensity of diffraction peaks of synthesized ZnO/porous silica nanocomposites could be an indication of a violation of the regularity in the pore structure of molecular sieve. The reason for this can be somewhat uneven distribution of ZnO in the silica matrix pores as in the case of CuO inside MCM-41 [25], FeCo inside SBA-16 [7] and Pt inside SBA-15 [26]. Based on the analysis of small-angle X-ray diffraction pattern results, ZnO may be located in the pores of the mesoporous silica matrix or on their external surface as individual particles.…”