Sol–gel processing of a bimetallic alkoxide precursor confined in a porous glass matrix: A route to novel glass/metal oxide nanocomposites

TiO2- and CeO2-Based Biphasic Core–Shell Nanoparticles with Tunable Core Sizes and Shell Thicknesses

“…Capillarity process rules the diffusion of the Ti(IV) and Ce(III) metalloorganic precursors into the PVG pores, as already reported in the literature for the incorporation of neutral molecules in the PVG. − At this stage, the precursor promotes coverage of the porous surface, establishing some nucleation sites due to its interaction with silanols (Si–OH) present on the matrix surface. During the decomposition process, dispersed nanocrystals are formed on these nucleation sites and they remain anchored to the matrix through Si–O–Ti and Si–O–Ce bonds .…”

“…During the decomposition process, dispersed nanocrystals are formed on these nucleation sites and they remain anchored to the matrix through Si–O–Ti and Si–O–Ce bonds . As already described in some papers, , PVG plays a fundamental role in controlling the coalescence process and nanoparticles formed inside the porous structure are dispersed and stabilized. With successive IDC, the exceeding interfacial free energy is expected to be minimized by nanoparticle growth.…”

“…For comparison, one may recall the result obtained for TiO 2 nanoparticles prepared inside PVG pores using the same IDC methodology and the same number of IDC. For PVG/ x TiO 2 ( x = 3, 5, or 7), the Raman E g mode experiences an energy upshift as the number of IDC increases, suggesting nanoparticle size growth: for PVG/3TiO 2 , the Raman E g mode is located at 157 cm –1 and for PVG/5TiO 2 and PVG/7TiO 2 the E g band occurs at 153 and 150 cm –1 , respectively . The E g Raman band positions for PVG/7CeO 2 y TiO 2 , equal to 163, 158, and 155 cm –1 for y = 3, 5, and 7, respectively, also present energy upshifts as the number of IDC increases.…”

The Synthesis and Characterization of Cobalt-Rice Husk Silica Nanoparticles

“…The synthesized material was characterized by fourier transformed infrared measurements (FT-IR, Perkin Elmer System 2000), 29 Si MAS nuclear magnetic resonance technique ( 29 Si MAS NMR, Bruker DSX-3000), N 2 sorption analysis (Micromeritics Instrument Corporation model ASAP 2000, Norcross) and X-ray diffractometry (XRD, Kristallofex Siemens, model D5000) equipped with Cu K radiation ( = 1.50 Å). The cobalt content was determined by atomic absorption spectroscopy (AAS, Perkin Elmer, model 3100).…”

“…Many studies have been reported on the use of silica from rice husk as a catalyst support [22][23][24][25]. Sol-gel process is claimed to be a simple and effective synthesis pathway for the production of nanomagnetite [26], silica nanotubes [27] and nanocomposites [28,29]. Moreover, recently, Zaky et al, [30] obtained a narrow size distribution of silica nanoparticles with an average size of 50-70 nm from semiburned rice straw ash.…”