Synthesis, Structure And Applications Of TiO2 Gels

1986 ◽  
Vol 73 ◽  
Author(s):  
J. Livage
Keyword(s):  
Molecular Level ◽  
Sol Gel ◽  
Photochemical Reactions ◽  
Titanium Alkoxides ◽  
Chemical Additives ◽  
Display Devices ◽  
Sol Gel Process ◽  
Infra Red ◽  
Tio2 Gels ◽  
Hydrolysis Of

ABSTRACTTiO2 gels are usually obtained through hydrolysis of titanium alkoxides. Chemical additives can however react with the precursor at a molecular level and therefore modify the hydrolysis-condensation reactions. Several examples will be described :acetic acid, acetylacetone or Cr(acac)3 The whole solgel process is followed all the way from the precursors to the gel and each step is characterized by spectroscopic experiments (Infra-red, N.M.R, E.S.R.). Some electronic properties of TiO2 gels are then described. Chemical additives allow an optimization of the sol-gel process according to each specific applications : electrochromic display devices, photoanodes or photochemical reactions.

Synthesis, Structure and Applications of TiO2 Gels

1986 ◽  
Vol 72 ◽  
Author(s):  
J. Livage
Keyword(s):  
Acetic Acid ◽  
Molecular Level ◽  
Sol Gel ◽  
Titanium Alkoxides ◽  
Chemical Additives ◽  
Display Devices ◽  
Sol Gel Process ◽  
Infra Red ◽  
Tio2 Gels ◽  
Hydrolysis Of

AbstractTiO2 gels are usually obtained through hydrolysis of titanium alkoxides. Chemical additives can however react with the precursor at a molecular level and therefore modify the hydrolysis-condensation reactions. Several examples will be described :acetic acid, acetylacetone or Cr(acac)3. The whole sol-gel process is followed all the way from the precursors to the gel and each step is characterized by spectroscopic experiments (Infra-red, N.M.R, E.S.R.). Some electronic properties of TiO2 gels are then described. Chemical addi-tives allow an optimization of thý sol-gel process according to each speci-fic applications : electrochromic display devices, photoanodes or photoche-mical reactions.

Raman and Infrared Study of Metal Alkoxides During Sol-Gel Process

1992 ◽  
Vol 271 ◽  
Author(s):  
O. Poncelet ◽  
J -C. Robert ◽  
J. Guilment
Keyword(s):  
Sol Gel ◽  
Analytical Techniques ◽  
Metal Alkoxides ◽  
Organic Additives ◽  
Chemical Additives ◽  
Reactive Metal ◽  
Infrared Study ◽  
Sol Gel Process ◽  
Hydrolysis Of Metal Alkoxides ◽  
Hydrolysis Of

ABSTRACTOrganic additives are commonly used in sol-gel chemistry [1]. They can operate as stabilizers of reactive metal alkoxides [2] towards hydrolysis or as drying control chemical additives (such as dimethylformamide). These organic compounds and the by-products of sol-gel reactions can drastically modify the physical properties of final oxide materials, so that it is necessary to optimize the use of these additives. The first steps of hydrolysis of metal alkoxides stabilized by organic additives have been studied by many sophisticated analytical techniques which are difficult to use at technical level and often strongly alter the sol-gel reactions [3]. We chose to use FT-Raman and Infrared spectrocopies, which allow to remain as close as possible of the sol-gel process without altering it. The first steps of hydrolysis of group (IVb) metal alkoxides, more particularly titanium, modified by chlorides, carboxylic acids and alkanolamines have been investigated.

Synthesis of Hollow Titania Photocatalytic Particles Using Yeast as Templates

2013 ◽  
Vol 699 ◽  
pp. 126-132 ◽  
Author(s):  
Toshiyuki Nomura ◽  
Syota Tanii ◽  
Hayato Tokumoto ◽  
Yasuhiro Konishi
Keyword(s):  
Pore Diameter ◽  
Sol Gel ◽  
Solid Particles ◽  
Core Shell ◽  
Average Pore ◽  
Inorganic Particles ◽  
Sol Gel Process ◽  
Yeast Powder ◽  
Titania Precursor ◽  
Hydrolysis Of

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.

Homogeneous phase synthesis of chitosan silica hybrid materials in ionic liquid medium and adsorption of Fe(III) from aqueous solutions

2019 ◽  
Vol 38 (9) ◽  
pp. 586-597 ◽  
Author(s):  
Ananda S. Amarasekara ◽  
Deping Wang
Keyword(s):  
Ionic Liquid ◽  
Hybrid Materials ◽  
Sol Gel ◽  
Phase Reaction ◽  
Phase Synthesis ◽  
Homogeneous Phase ◽  
Sol Gel Process ◽  
Hydrolysis Of ◽  
Silica Hybrid ◽  
Ionic Liquid Medium

Two chitosan silica hybrid materials were prepared by a two-step process in 78–84% yields using the homogeneous phase reaction of 3-(triethoxysilyl)propyl isocyanate with chitosan dissolved in 1-n-butyl-3-methylimidazolium chloride ionic liquid (∼10% w/w), which was followed by NH4OH catalyzed hydrolysis of triethoxysilyl groups and then sol-gel process. These new hybrid materials were shown to adsorb up to about 95% of Fe3+ from 5 × 10−4 M aqueous solution at room temperature in 24 h.

scholarly journals Cross-Condensation Reactions in an Organically Modified Silica Sol-Gel

1994 ◽  
Vol 346 ◽  
Author(s):  
S. Prabakar ◽  
R. A. Assink ◽  
N. K. Raman ◽  
C. J. Brinker
Keyword(s):  
Experimental Error ◽  
Molecular Level ◽  
Sol Gel ◽  
Resonance Assignments ◽  
Silica Sol ◽  
Modified Silica ◽  
Organically Modified ◽  
Organically Modified Silica ◽  
Acid Catalyzed ◽  
Hydrolysis Of

ABSTRACTHigh resolution 29Si NMR has been used to study the extent of cross condensation taking place in a hybrid organic/inorganic sol-gel system. Tetraethoxysilane (TEOS) and methyltriethoxysilane (MTEOS) sol-gels were chosen for this purpose. The sols were prepared by acid catalyzed hydrolysis of TEOS and MTEOS with a H2O/Si ratio of 0.3. 29Si NMR shows signals due to both self-condensation and cross-condensation between TEOS and MTEOS. Resonance assignments were made by comparing the positions and intensities of peaks in the spectra of single and multicomponent systems. It was found that, within experimental error, the self- and cross-condensation rates are equal and that extensive molecular level mixing takes place during the early stages of the reaction.

Preparation and Electrophoretic Deposition of an Yttrium Silicate Precursor Sol

2009 ◽  
Vol 412 ◽  
pp. 267-272 ◽  
Author(s):  
Jana Grosse-Brauckmann ◽  
Günter Borchardt ◽  
Christos Argirusis
Keyword(s):  
Electrophoretic Deposition ◽  
Sol Gel ◽  
Constant Current ◽  
Particle Charge ◽  
Yttrium Silicate ◽  
Micro Cracks ◽  
Sol Gel Process ◽  
Hydrolysis Of ◽  
Controlled Hydrolysis

. In the present work we used the sol-gel process to prepare Y2SiO5 precursor sols suitable for electrophoretic deposition (EPD). The sol synthesis was performed through the controlled hydrolysis of alkoxide solutions of tetraethoxysilane and yttriumoxoisopropoxide. During sol development emphasis was put on characterization of particles size and zeta potential of the formed aggregates. We succeeded in synthesizing a clear sol containing polymeric aggregates with acceptable particle charge. The electrophoretic deposition on glassy carbon or C/C-SiC slabs led to homogenous layers. At low sol concentrations micro cracks in the deposited layers were observed whereas higher concentrations led to thin and dense layers. During constant current EPD a constant voltage was recorded indicating that the deposited layer does not lead to an increase in resistivity in this kind of EPD system.

Leaching Behavior of Edta In A Silica Sol-Gel Matrix

1994 ◽  
Vol 346 ◽  
Author(s):  
Kris S. Oka ◽  
J.D. Mackenzie
Keyword(s):  
Pore Volume ◽  
Sol Gel ◽  
Silica Matrix ◽  
Silica Gels ◽  
Volume Distribution ◽  
Leaching Behavior ◽  
Sol Gel Process ◽  
The Matrix ◽  
Physical Changes ◽  
Hydrolysis Of

ABSTRACTEthylene diamine tetra-acetic acid (EDTA) doped silica gels were made by the sol-gel process for the potential application as a filter for heavy metal ions in wastewater. The behavior of the organic molecule in the matrix was studied by investigating the percentage of EDTA leached out with a variation in the timing of addition of the EDTA molecule into the starting silica gel solution. Leach tests using water as the medium were performed for 2, 12 and 24 hours in order to determine the amount of EDTA trapped in the pores or in the matrix. A minimum amount of EDTA leached from the gels was detected in the samples to which EDTA was added 4 hours after initial hydrolysis of TEOS. This result was correlated to having a greater percentage of pore volume in the range of 15–20 Å, which was further substantiated with density measurements. The physical changes in the silica matrix altering the pore volume distribution were attributed to the addition of the water into which the EDTA molecule was initially dissolved.

Improvement in Mechanical Property of SiO2 Films Prepared by Sol-Gel

2013 ◽  
Vol 744 ◽  
pp. 269-272 ◽  
Author(s):  
Pei Tao Guo
Keyword(s):  
Mechanical Property ◽  
Thermal Treatment ◽  
Young’S Modulus ◽  
Young's Modulus ◽  
Sol Gel ◽  
Dimethyl Formamide ◽  
Good Mechanical Property ◽  
Chemical Additives ◽  
Sol Gel Process ◽  
Silica Sols

Silica films prepared by the base catalyzed sol–gel process show poor mechanical property. In this study, silica anti-reflective films with good mechanical property have been prepared by the catalyzed sol–gel process with dimethyl formamide added as drying control chemical additives. The silica sol was first dip deposited onto substrate to form films on both sides of the substrate and then subjected to thermal treatment. After thermal treatment, the film was achieved due to the formation of porous structure in the resultant film as a result of decomposing tetraethylorthosilicate and dimethyl formamide. Nano-indenter measurement shows that the Young’s modulus and hardness of base catalyzed films are 10-20GPa and 0.25-0.55GPa, respectively. But the films added with dimethyl formamide are much better than those films derived from base-catalyzed silica sols, the Young’s modulus and hardness are 32-39GPa and 1.22-1.47GPa, respectively. The good mechanical properties make such films potential in both military and civil applications.

A novel bulk sol-gel process to prepare monolithic silica materials

1999 ◽  
Vol 14 (10) ◽  
pp. 4098-4102 ◽  
Author(s):  
Ce Wang ◽  
Yahong Zhang ◽  
Yunfeng Lu ◽  
Yen Wei
Keyword(s):  
Sol Gel ◽  
Silica Content ◽  
Monolithic Silica ◽  
Nonpolar Solvents ◽  
Sol Gel Process ◽  
Silica Materials ◽  
High Silica ◽  
Acid Catalyzed ◽  
Carbonate Salts ◽  
Hydrolysis Of

A bulk sol-gel process has been developed to prepare monolithic silica materials at room temperature. The process involves an acid-catalyzed hydrolysis of tetraethyl orthosilicate in tetrahydrofuran containing aqueous HC1 catalyst, followed by neutralization with carbonate salts, extraction with aliphatic nonpolar solvents, molding, gelation, and drying. This method shortens the processing time from weeks for the conventional sol-gel process to several days. The silica objects prepared from the process are transparent, crack-free, and of relatively low volume shrinkage (e.g., 52%) and high silica content (e.g., 82%).

Photochemical reactions of Ge-related defects in 10GeO2·90SiO2 glass prepared by sol–gel process

1999 ◽  
Vol 259 (1-3) ◽  
pp. 149-155 ◽  
Author(s):  
Masahide Takahashi ◽  
Hikari Shigemura ◽  
Yoji Kawamoto ◽  
Junji Nishii ◽  
Toshinobu Yoko
Keyword(s):  
Sol Gel ◽  
Photochemical Reactions ◽  
Sol Gel Process
Sign in / Sign up

Export Citation Format

Share Document