Control of mesoporosity of carbon gels prepared by sol–gel polycondensation and freeze drying

2001 ◽  
Vol 288 (1-3) ◽  
pp. 46-55 ◽  
Author(s):  
T Yamamoto ◽  
T Nishimura ◽  
T Suzuki ◽  
H Tamon
Keyword(s):  
Freeze Drying ◽  
Sol Gel ◽  
Carbon Gels

Improvement of Mesopore Structure of Resorcinol and Formaldehyde Carbon Cryogels by Acid Solution

2008 ◽  
Vol 55-57 ◽  
pp. 529-532
Author(s):  
K. Kraiwattanawong ◽  
P. Kitchaiya ◽  
Arthit Neramittagapong ◽  
P. Praserthdam ◽  
H. Tamon
Keyword(s):  
Acid Solution ◽  
Pore Structure ◽  
Freeze Drying ◽  
Sol Gel ◽  
Inert Atmosphere ◽  
Size Distributions ◽  
Large Pore ◽  
Small Pore ◽  
Carbon Gels ◽  
Mesopore Structure

Resorcinol and formaldehyde (RF) carbon cryogels are prepared by sol-gel polycondensation by using sodium carbonate (C) as a catalyst with water (W) as solvent, immersed in acid solution, hydrochloric acid (HCl), dried by freeze-drying technique and then carbonized under inert atmosphere, respectively. Compared with their carbon precursors, both Vmes and mesopore size distributions of all carbon cryogels can be developed since the pore shrinkage is the crucial role in the change of pore structure of carbon gels. HCl may promote the strength of small pore structure and increase the pore shrinkage of large pore structure. Consequently, the treatment of HCl does not only enhance the partial collapse of large pore structure, the treatment also increases the strength of small pore structure to inhibit the shrinkage of this structure during carbonization as well.

scholarly journals Elucidation of the Crystal Growth Characteristics of SnO2 Nanoaggregates Formed by Sequential Low-Temperature Sol-Gel Reaction and Freeze Drying

Nanomaterials ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1738
Author(s):  
Saeid Vafaei ◽  
Alexander Wolosz ◽  
Catlin Ethridge ◽  
Udo Schnupf ◽  
Nagisa Hattori ◽  
...  
Keyword(s):  
Crystal Growth ◽  
Low Temperature ◽  
Photoelectron Spectroscopy ◽  
High Performance ◽  
Freeze Drying ◽  
Sno2 Nanoparticles ◽  
Sol Gel ◽  
Functional Materials ◽  
Cost Effective ◽  
High Concentration

SnO2 nanoparticles are regarded as attractive, functional materials because of their versatile applications. SnO2 nanoaggregates with single-nanometer-scale lumpy surfaces provide opportunities to enhance hetero-material interfacial areas, leading to the performance improvement of materials and devices. For the first time, we demonstrate that SnO2 nanoaggregates with oxygen vacancies can be produced by a simple, low-temperature sol-gel approach combined with freeze-drying. We characterize the initiation of the low-temperature crystal growth of the obtained SnO2 nanoaggregates using high-resolution transmission electron microscopy (HRTEM). The results indicate that Sn (II) hydroxide precursors are converted into submicrometer-scale nanoaggregates consisting of uniform SnO2 spherical nanocrystals (2~5 nm in size). As the sol-gel reaction time increases, further crystallization is observed through the neighboring particles in a confined part of the aggregates, while the specific surface areas of the SnO2 samples increase concomitantly. In addition, X-ray photoelectron spectroscopy (XPS) measurements suggest that Sn (II) ions exist in the SnO2 samples when the reactions are stopped after a short time or when a relatively high concentration of Sn (II) is involved in the corresponding sol-gel reactions. Understanding this low-temperature growth of 3D SnO2 will provide new avenues for developing and producing high-performance, photofunctional nanomaterials via a cost-effective and scalable method.

Nanocomposites LiMnxFe1-xPO4/C synthesized via freeze drying assisted sol-gel routine and their magnetic and electrochemical properties

2019 ◽  
Vol 779 ◽  
pp. 339-346 ◽  
Author(s):  
Liying Liu ◽  
Zujie Cao ◽  
Yanyan Cui ◽  
Xi Ke ◽  
Guoxun Zeng ◽  
...  
Keyword(s):  
Electrochemical Properties ◽  
Freeze Drying ◽  
Sol Gel

scholarly journals Synthesis and Characterization of Nanosized of Spinel LiMn2O4via Sol-gel and Freeze Drying Methods

2013 ◽  
Vol 34 (2) ◽  
pp. 622-628 ◽  
Author(s):  
Masoud Seyedahmadian ◽  
Shadi Houshyarazar ◽  
Ahmad Amirshaghaghi
Keyword(s):  
Freeze Drying ◽  
Sol Gel ◽  
Synthesis And Characterization ◽  
Drying Methods

scholarly journals Enhanced lithium storage performance of V2O5 with oxygen vacancy

RSC Advances ◽  
2018 ◽  
Vol 8 (69) ◽  
pp. 39371-39376 ◽  
Author(s):  
Yinlu Sun ◽  
Zhiping Xie ◽  
Yanwei Li
Keyword(s):  
Oxygen Vacancy ◽  
Freeze Drying ◽  
Vacuum Annealing ◽  
Sol Gel ◽  
Orthorhombic Phase ◽  
Annealing Process ◽  
Lithium Storage ◽  
Gel Method ◽  
Storage Performance ◽  
Drying Technology

Orthorhombic phase V2O5 nanosheets with a high V4+ content (V-V2O5) have been fabricated via a facile sol–gel method and freeze-drying technology followed with a vacuum annealing process.

Effect of drying conditions on mesoporosity of carbon precursors prepared by sol–gel polycondensation and freeze drying

Carbon ◽  
2001 ◽  
Vol 39 (15) ◽  
pp. 2374-2376 ◽  
Author(s):  
T Yamamoto ◽  
T Nishimura ◽  
T Suzuki ◽  
H Tamon
Keyword(s):  
Freeze Drying ◽  
Sol Gel ◽  
Drying Conditions

Coated Hydrophilic Thin Film on Glasses Using Freeze Drying-Assisted Sol-Gel Technique for Self-Cleaning Building Materials

2010 ◽  
Vol 150-151 ◽  
pp. 1484-1487 ◽  
Author(s):  
Tao Lin ◽  
Xiang Chao Zhang
Keyword(s):  
Thin Film ◽  
Tio2 Film ◽  
Freeze Drying ◽  
Building Materials ◽  
Tio2 Thin Film ◽  
Sol Gel ◽  
Contact Angles ◽  
Ito Glass ◽  
Gel Technique ◽  
Self Cleaning

Titanium dioxide thin film has been successfully synthesized deposited on ITO glass substrates by the sol–gel dip-coating method using freeze drying technique. The precursor and TiO2 film were characterized using XRD, AFM and UV-vis absorption spectra analysis technologies. The XRD result demonstrates that the TiO2 film is well crystallized and consists of anatase phase only with (101) plane. The morphology of the nanoparticles of TiO2 thin film is spherical shape with grain size of 30.1 nm in average diameter and the surface of the TiO2 film is smooth. There is a strong wide UV absorption band around 387 nm and the calculated band gap (Eg) value of the TiO2 thin film is about 3.18 eV. The water contact angles for the thin film was only about 12°. The freeze drying-assisted sol-gel technique offers a novel process route in treating hydrophilic glasses for self-cleaning building materials and would be widely application for building energy saving.

Freeze-drying assisted sol–gel-derived silica-based particles embedding iron: synthesis and characterization

2018 ◽  
Vol 87 (1) ◽  
pp. 195-203 ◽  
Author(s):  
L. B. Chiriac ◽  
M. Todea ◽  
A. Vulpoi ◽  
M. Muresan-Pop ◽  
R. V. F. Turcu ◽  
...  
Keyword(s):  
Freeze Drying ◽  
Sol Gel ◽  
Synthesis And Characterization

scholarly journals Fabrication Of Carbon Aerogels From Coir For Oil Adsorption

2022 ◽  
Vol 964 (1) ◽  
pp. 012033
Author(s):  
Hieu M Nguyen ◽  
Khoi A Tran ◽  
Tram T N Nguyen ◽  
Nga N H Do ◽  
Kien A Le ◽  
...  
Keyword(s):  
Freeze Drying ◽  
Oil Spills ◽  
Sol Gel ◽  
Urea Solution ◽  
Carbon Aerogels ◽  
Low Density ◽  
High Porosity ◽  
Motor Oil ◽  
Sol Gel Process ◽  
Oil Adsorption

Abstract Coir, known as coconut fibers, are an abundant cellulosic source in Vietnam, which are mostly discarded when copra and coconut water are taken, causing environmental pollution and waste of potential biomass. In this research, carbon aerogels from chemically pretreated coir were successfully synthesized via simple sol-gel process with NaOH-urea solution, economical freeze-drying, and carbonization. The samples, including pretreated coir, coir aerogels, and carbon aerogels, are characterized using FTIR spectroscopy, SEM, XRD spectroscopy, and TGA. The carbon aerogels exhibit low density (0.034–0.047 g/cm3), high porosity (97.63–98.32 %), and comparable motor oil sorption capacity (22.71 g/g). The properties of carbon aerogels are compared with those of coir aerogels, indicating such better values than those of coir aerogels. Coir-derived carbon aerogels is a potential replacement for the hydrophobically-coated cellulose aerogels in term of treating oil spills.

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