A facile process for generating monolithic-structured nano-silica/polystyrene multi-core/shell microspheres by a seeded sol–gel process method

Hollow inorganic particles have attracted considerable interest for a variety of applications. In this work, yeast powder was used as a bio-template to fabricate yeast/titania core-shell spheres. A titania precursor was deposited via the hydrolysis of tetraisopropyl titanate. Triethanolamine was employed to control the reaction rate of the sol-gel process. The hollow titania particles with a diameter of approximately 4 m and a thickness of approximately 54 nm were successfully obtained after calcination of the core-shell spheres at 700 °C. The crystal structure of the particles was anatase. The specific surface area and the average pore diameter were 21.4 m2/g and 1.6 nm, respectively. The photocatalytic activity of the hollow particles was higher compared with that of solid particles.

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Effect of Cores on Photoluminescence of Hybrid SiO2-Coated CdTe Quantum Dots

Journal of Nanoscience and Nanotechnology ◽

10.1166/jnn.2020.17877 ◽

2020 ◽

Vol 20 (9) ◽

pp. 5478-5485

Author(s):

Cong Xie ◽

Yubin Zhao ◽

Yuxiang Song ◽

Yingjie Liu ◽

Yaya Wang ◽

...

Keyword(s):

Quantum Dots ◽

High Stability ◽

Sol Gel ◽

Quantum Yields ◽

Core Shell ◽

Aqueous Synthesis ◽

Pl Spectra ◽

Cdte Qds ◽

Sol Gel Process ◽

20 Nm

Compared with conventional semiconductor quantum dots, hybrid SiO2 coated CdTe QDs exhibited high stability, long fluorescent lifetime, high photoluminescence quantum yields, and well biocompatibility. In this paper, CdTe QDs with tunable PL from green to red emitting were prepared by an aqueous synthesis. A sol–gel process resulted in CdTe QDs coated with a hybrid SiO2 shell contained CdS-like clusters to obtain red-shifted PL spectra, increased PL efficiency and high stability. The clusters were formed by the reaction of Cd2+ and S2− ions generated via the decomposition of thioglycolic acid. The clusters around CdTe cores created a core–shell structure which is very similar with traditional semiconductor core–shell QDs. After being coated with a hybrid SiO2 shell, the PL of green-emitting naked CdTe QDs was red-shifted largely (~30 nm) while the PL of yellowemitting CdTe QDs revealed a small red-shifted (~20 nm). Furthermore, The PL of red-emitting naked CdTe QDs was red-shifted much small (less than 10 nm). This phenomenon is ascribed to the change of band gap of CdTe cores with sizes. The red-shift of PL spectra is attributed to the CdS-like clusters around the core rather than the thickness of the hybrid SiO2 shell.

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Synthesis and Characterization of SiO2@Y2MoO6:Eu3+ Core–Shell Structured Spherical Phosphors by Sol–Gel Process

Journal of Nanoscience and Nanotechnology ◽

10.1166/jnn.2016.11862 ◽

2016 ◽

Vol 16 (4) ◽

pp. 3914-3920 ◽

Cited By ~ 1

Author(s):

G. Z Li ◽

F. H Liu ◽

Z. S Chu ◽

D. M Wu ◽

L. B Yang ◽

...

Keyword(s):

Electron Microscopy ◽

Annealing Temperature ◽

Uv Light ◽

Sol Gel ◽

Spherical Shape ◽

Core Shell ◽

X Ray ◽

Transmission Electron ◽

Sol Gel Process ◽

Average Size

SiO2@Y2MoO6:Eu3+ core–shell phosphors were prepared by the sol–gel process. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectra (EDS), transmission electron microscopy (TEM), photoluminescence (PL) spectra as well as kinetic decays were used to characterize the resulting SiO2@Y2MoO6:Eu3+ core–shell phosphors. The XRD results demonstrated that the Y2MoO6:Eu3+ layers on the SiO2 spheres crystallized after being annealed at 700 °C and the crystallinity increased with raising the annealing temperature. The obtained core–shell phosphors have spherical shape with narrow size distribution (average size ca. 640 nm), non-agglomeration, and smooth surface. The thickness of the Y2MoO6:Eu3+ shells on the SiO2 cores could be easily tailored by varying the number of deposition cycles (70 nm for four deposition cycles). The Eu3+ shows a strong PL emission (dominated by 5D0–7F2 red emission at 614 nm) under the excitation of 347 nm UV light. The PL intensity of Eu3+ increases with increasing the annealing temperature and the number of coating cycles.

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Synthesis of hollow mesoporous silica microspheres through surface sol–gel process on polystyrene-co-poly(4-vinylpyridine) core–shell microspheres

Microporous and Mesoporous Materials ◽

10.1016/j.micromeso.2010.10.002 ◽

2011 ◽

Vol 139 (1-3) ◽

pp. 1-7 ◽

Cited By ~ 40

Author(s):

Shengnan Wang ◽

Minchao Zhang ◽

Da Wang ◽

Wangqing Zhang ◽

Shuangxi Liu

Keyword(s):

Mesoporous Silica ◽

Sol Gel ◽

Core Shell ◽

Silica Microspheres ◽

Sol Gel Process ◽

Mesoporous Silica Microspheres ◽

Hollow Mesoporous Silica

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The Preparation of Fluorescent Nano Dye-Silica Particles by Sol-Gel Process

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.124-126.651 ◽

2007 ◽

Vol 124-126 ◽

pp. 651-654 ◽

Cited By ~ 2

Author(s):

Young Joo Na ◽

Sang Joon Park ◽

Ji Hyeon Kim ◽

Jong Sung Kim

Keyword(s):

Shell Structure ◽

Sol Gel ◽

Silica Nanoparticle ◽

Fluorescent Dye ◽

Core Shell ◽

Fluorescent Intensity ◽

Sol Gel Process ◽

Fluorescent Spectrum ◽

Core Shell Structure ◽

Trimethoxy Silane

The core-shell structure of dye-silica nanoparticle has been prepared. The dye-silica nanoparticle can be used as a substitute of fluorescent dye for bio analysis. The hybrid organicinorganic nanoparticle was prepared by sol-gel process using organic modified silane as the coupling agent for flourescent dye and silica. The size of the particle was about 50 nm, which was measured by DLS and confirmed by SEM photograph. The fluorescent dye (fluorescein-5-maleimide) was reacted with (3-mercaptopropyl) trimethoxy silane to produce dye-silane compound, followed by the sol-gel reaction with tetraethoxysilane(TEOS) and water to produce core-shell structure. The fluorescent spectrum showed that the fluorescent intensity of dye-silica nanoparticle was higher than that of fluorescent dye.

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Synthesis and Characterization of Ag Nanoparticle, Ag-TiO2 Nanoparticle and Ag-TiO2-Chitosan Complex and Their Application to Antibiosis and Deodorization

MRS Proceedings ◽

10.1557/proc-820-o8.16 ◽

2004 ◽

Vol 820 ◽

Cited By ~ 2

Author(s):

Young Hwan Kim ◽

Young Soo Kang

Keyword(s):

Thermal Decomposition ◽

Sol Gel ◽

Oxide Shell ◽

Synthesis And Characterization ◽

Core Shell ◽

Ag Nanoparticle ◽

Sol Gel Process ◽

Core Shell Structure ◽

Silver Core

AbstractAg nanoparticles have been prepared by thermal decomposition of Ag-oleate complex using electric furnace at 300 °C for about 4 hrs. TEM images of the particles showed 2-dimensional assembly of particles with diameter of 8.0 ± 1.3 nm, demonstrating the uniformity of these nanoparticles. Ag-TiO2 nanoparticles were synthesized by sol-gel process and they had core-shell structure. Results showed the formation of the silver core and titanium oxide shell. In this study, we investigated the structure of Ag nanoparticle and Ag-TiO2 nanoparticle and Ag-TiO2-chitosan complex and their functions of antibiosis and deodorization.

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Design of SiO2/ZrO2 core–shell particles using the sol–gel process

Ceramics International ◽

10.1016/j.ceramint.2008.06.003 ◽

2009 ◽

Vol 35 (3) ◽

pp. 1243-1247 ◽

Cited By ~ 30

Author(s):

Jong Min Kim ◽

Sang Mok Chang ◽

Sungkook Kim ◽

Kyo-Seon Kim ◽

Jinsoo Kim ◽

...

Keyword(s):

Sol Gel ◽

Core Shell ◽

Sol Gel Process ◽

Shell Particles

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Structure and Luminescence of Europium-Doped Gadolinia-Based Core/Multi-Shell Scintillation Nanoparticles

MRS Proceedings ◽

10.1557/proc-1164-l11-01 ◽

2009 ◽

Vol 1164 ◽

Author(s):

Teng-Kuan Tseng ◽

Jihun Choi ◽

Paul H. Holloway

Keyword(s):

Charge Transfer Band ◽

Sol Gel ◽

Core Shell ◽

Photoluminescence Excitation ◽

Shell Nanoparticles ◽

Direct Excitation ◽

Transmission Electron ◽

Sol Gel Process ◽

Pl Emission ◽

Core Shell Nanoparticles

AbstractScintillating nanoparticles with a SiO2 core and a Gd2O3 shell doped with Eu3+ were synthesized with a sol-gel process. Based on transmission electron microscopy (TEM) data, a ∼13 nm Gd2O3 shell was successfully coated onto ∼220 nm mono-dispersed SiO2 nanocores. Eu3+ ions at concentrations of nominally 5 at% exhibited photoluminescent (PL) emission from the SiO2/Gd2O3 nanoparticles after being calcined at 800 0C for 2 h. The SiO2 remained amorphous after calcining, while the Gd2O3 crystallized to a cubic structure. The PL emission was from the 5D0-7F2 transitions of Eu3+ at 609 and 622 nm. Photoluminescence excitation (PLE) data showed that emission from Eu3+ could result from direct excitation, but was dominated by the oxygen to europium charge-transfer band (CTB) between 250 and 280 nm for Eu3+ doped in Gd2O3. The quantum yield (QY) from thin films drop cast from a mixture of 20 mg of calcined nanoparticles in 500 μL of polymethylmethacrylate (PMMA) and excited in the CTB was 20% for SiO2/Gd2O3:Eu3+ core/shell scintillation nanoparticles. Finally, the above core/shell nanoparticles were passivated with a shell of SiO2 to create e.g. SiO2/Gd2O3:Eu3+/SiO2 nanoparticles. The QYs for this nanostructure were lower than unpassivated nanoparticles which was attributed to a weak CTB for the amorphous SiO2 shell and a higher density of interface quenching sites.

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Titania encapsulation of flat gold nanoparticles — A simple route to Au@TiO2 core-shell nanosheets

Canadian Journal of Chemistry ◽

10.1139/v08-064 ◽

2008 ◽

Vol 86 (7) ◽

pp. 703-708 ◽

Cited By ~ 4

Author(s):

Jeffrey J McDowell ◽

J Ian McKelvey ◽

Laura A Richard ◽

Jeffrey T Banks

Keyword(s):

Thin Films ◽

Gold Nanoparticles ◽

Sol Gel ◽

Core Shell ◽

Simple Route ◽

Uniform Coating ◽

Anisotropic Nanoparticles ◽

Microwave Reactor ◽

Semiconductor Thin Films ◽

Sol Gel Process

We report the attachment of a uniform coating of a thin layer of amorphous TiO2 to flat gold nanoparticles via a simple sol–gel process. Coatings of variable thickness ranging from 5 to 100 nm have been produced. Activation of the Au particles was unnecessary. However, the ability to coat the flat gold nanoparticles was dependent on the method used for their synthesis. In addition, the amorphous TiO2 shell was hydrothermally treated to induce crystallization to the anatase polymorph. The desired nanocrystalline anatase morphology was obtained by heating in water at 70 °C for 1 week. A similar result was also obtained when the material was heated to 130 °C for 5 min in a microwave reactor. These new Au@TiO2 nanosheets were characterized by TEM, EDX, and SAED.Key words: core-shell, titanium dioxide, anisotropic nanoparticles, semiconductor thin films, nanocomposite material.

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