scholarly journals Resorcinol-Formaldehyde and Carbon Aerogel Microspheres

1996 ◽  
Vol 431 ◽  
Author(s):  
C. T. Alviso ◽  
R. W. Pekala ◽  
J. Gross ◽  
X. Lu ◽  
R. Caps ◽  
...  
Keyword(s):  
Cell Structure ◽  
High Surface ◽  
High Surface Area ◽  
Thermal Characterization ◽  
Supercritical Drying ◽  
Carbon Aerogel ◽  
Solid Matrix ◽  
Attractive Alternative ◽  
Resorcinol Formaldehyde ◽  
Potential Applications

AbstractAerogels are a unique class of materials possessing an open-cell structure with ultrafine cells/pores (<100nm), high surface area (400–1100 m2/g), and a solid matrix composed of interconnected particles, fibers, or platelets with characteristic dimensions of 10nm. Although monolithic aerogels are ideal candidates for many applications (e.g. transparent window insulation), current processing methods have limited their introduction into the commercial marketplace. Our research focuses on the formation of resorcinol-formaldehyde (RF) aerogel microspheres which offer an attractive alternative to monolith production. An inverse emulsion polymerization is used to produce these spherical gel particles which undergo solvent exchange followed by supercritical drying with carbon dioxide. This process yields aerogel microspheres (10–80μ diameter) which can be used as loosely packed powders, compression molded into nearnet shapes using a polymer binder, or used as additives in conventional foaming operations to produce new aerogel composites with superior thermal properties. The emulsification procedure, thermal characterization, mechanical properties, and potential applications of RF aerogel microspheres will be discussed.

scholarly journals Electrochemical Behavior of Carbon Aerogels Derived From Different Precursors

1995 ◽  
Vol 393 ◽  
Author(s):  
R.W. Pekala ◽  
C.T. Alviso ◽  
J.K. Nielsen ◽  
T.D. Tran ◽  
G.A.M. Reynolds ◽  
...  
Keyword(s):  
Cell Structure ◽  
High Surface ◽  
Sol Gel ◽  
High Surface Area ◽  
Supercritical Drying ◽  
Inert Atmosphere ◽  
Solid Matrix ◽  
Carbon Aerogels ◽  
Energy Storage Devices ◽  
Electrochemical Double Layer

ABSTRACTThe ability to tailor the structure and properties of porous carbons has led to their increased use as electrodes in energy storage devices. Our research focuses on the synthesis and characterization of carbon aerogels for use in electrochemical double layer capacitors. Carbon aerogels are formed from the sol-gel polymerization of (1) resorcinol-formaldehyde or (2) phenolic-furfural, followed by supercritical drying from carbon dioxide, and subsequent pyrolysis in an inert atmosphere. These materials can be produced as monoliths, composites, thin films, powders, or microspheres. In all cases, the aerogels have an open-cell structure with an ultrafine pore size (<100 nm), high surface area (400-1100 m2/g), and a solid matrix composed of interconnected particles, fibers, or platelets with characteristic dimensions of 10 nm. This paper examines the effects of the carbon precursor and processing conditions on electrochemical performance in aqueous and organic electrolytes.

Gas permeability of carbon aerogels

1993 ◽  
Vol 8 (12) ◽  
pp. 3100-3105 ◽  
Author(s):  
F-M. Kong ◽  
J.D. LeMay ◽  
S.S. Hulsey ◽  
C.T. Alviso ◽  
R.W. Pekala
Keyword(s):  
Pore Size ◽  
Gas Flow ◽  
Gas Permeability ◽  
High Surface ◽  
High Surface Area ◽  
Supercritical Drying ◽  
Flow Equation ◽  
Carbon Aerogels ◽  
Thin Specimen ◽  
Potential Applications

Carbon aerogels are synthesized via the aqueous polycondensation of resorcinol with formaldehyde, followed by supercritical drying and subsequent pyrolysis at 1050 °C. As a result of their interconnected porosity, ultrafine cell/pore size, and high surface area, carbon aerogels have many potential applications such as supercapacitors, battery electrodes, catalyst supports, and gas filters. The performance of carbon aerogels in the latter two applications depends on the permeability or gas flow conductance in these materials. By measuring the pressure differential across a thin specimen and the nitrogen gas flow rate in the viscous regime, the permeability of carbon aerogels was calculated from equations based upon Darcy's law. Our measurements show that carbon aerogels have permeabilities on the order of 10−12 to 10−10 cm2 over the density range from 0.05–0.44 g/cm3. Like many other aerogel properties, the permeability of carbon aerogels follows a power law relationship with density, reflecting differences in the average mesopore size. Comparing the results from this study with the permeability of silica aerogels reported by other workers, we found that the permeability of aerogels is governed by a simple universal flow equation. This paper discusses the relationship among permeability, pore size, and density in carbon aerogels.

scholarly journals Metal-Organic Framework-Based Engineered Materials—Fundamentals and Applications

Molecules ◽  
2020 ◽  
Vol 25 (7) ◽  
pp. 1598 ◽  
Author(s):  
Tahir Rasheed ◽  
Komal Rizwan ◽  
Muhammad Bilal ◽  
Hafiz M. N. Iqbal
Keyword(s):  
Drug Delivery ◽  
Metal Organic Framework ◽  
High Surface ◽  
High Surface Area ◽  
Co2 Reduction ◽  
Biological Species ◽  
Crystalline Materials ◽  
Potential Applications ◽  
Metal Organic ◽  
Catalytic Chemistry

Metal-organic frameworks (MOFs) are a fascinating class of porous crystalline materials constructed by organic ligands and inorganic connectors. Owing to their noteworthy catalytic chemistry, and matching or compatible coordination with numerous materials, MOFs offer potential applications in diverse fields such as catalysis, proton conduction, gas storage, drug delivery, sensing, separation and other related biotechnological and biomedical applications. Moreover, their designable structural topologies, high surface area, ultrahigh porosity, and tunable functionalities all make them excellent materials of interests for nanoscale applications. Herein, an effort has been to summarize the current advancement of MOF-based materials (i.e., pristine MOFs, MOF derivatives, or MOF composites) for electrocatalysis, photocatalysis, and biocatalysis. In the first part, we discussed the electrocatalytic behavior of various MOFs, such as oxidation and reduction candidates for different types of chemical reactions. The second section emphasizes on the photocatalytic performance of various MOFs as potential candidates for light-driven reactions, including photocatalytic degradation of various contaminants, CO2 reduction, and water splitting. Applications of MOFs-based porous materials in the biomedical sector, such as drug delivery, sensing and biosensing, antibacterial agents, and biomimetic systems for various biological species is discussed in the third part. Finally, the concluding points, challenges, and future prospects regarding MOFs or MOF-based materials for catalytic applications are also highlighted.

scholarly journals Toxicity Studies on Graphene-Based Nanomaterials in Aquatic Organisms: Current Understanding

Molecules ◽  
2020 ◽  
Vol 25 (16) ◽  
pp. 3618
Author(s):  
Nemi Malhotra ◽  
Oliver B. Villaflores ◽  
Gilbert Audira ◽  
Petrus Siregar ◽  
Jiann-Shing Lee ◽  
...  
Keyword(s):  
High Surface ◽  
High Surface Area ◽  
Aquatic Organisms ◽  
Current Understanding ◽  
Toxic Effects ◽  
Fish Cell ◽  
Conductivity Electron ◽  
Potential Applications ◽  
Aquatic Food ◽  
Living Organisms

Graphene and its oxide are nanomaterials considered currently to be very promising because of their great potential applications in various industries. The exceptional physiochemical properties of graphene, particularly thermal conductivity, electron mobility, high surface area, and mechanical strength, promise development of novel or enhanced technologies in industries. The diverse applications of graphene and graphene oxide (GO) include energy storage, sensors, generators, light processing, electronics, and targeted drug delivery. However, the extensive use and exposure to graphene and GO might pose a great threat to living organisms and ultimately to human health. The toxicity data of graphene and GO is still insufficient to point out its side effects to different living organisms. Their accumulation in the aquatic environment might create complex problems in aquatic food chains and aquatic habitats leading to debilitating health effects in humans. The potential toxic effects of graphene and GO are not fully understood. However, they have been reported to cause agglomeration, long-term persistence, and toxic effects penetrating cell membrane and interacting with cellular components. In this review paper, we have primarily focused on the toxic effects of graphene and GO caused on aquatic invertebrates and fish (cell line and organisms). Here, we aim to point out the current understanding and knowledge gaps of graphene and GO toxicity.

scholarly journals From double-helix structured seaweed to S-doped carbon aerogel with ultra-high surface area for energy storage

2019 ◽  
Vol 17 ◽  
pp. 22-30 ◽  
Author(s):  
Daohao Li ◽  
Guojing Chang ◽  
Lu Zong ◽  
Pan Xue ◽  
Yu Wang ◽  
...  
Keyword(s):  
Energy Storage ◽  
Surface Area ◽  
Double Helix ◽  
High Surface ◽  
High Surface Area ◽  
Carbon Aerogel

Double layer capacitance of high surface area carbon nanospheres derived from resorcinol–formaldehyde polymers

Carbon ◽  
2011 ◽  
Vol 49 (14) ◽  
pp. 4848-4857 ◽  
Author(s):  
Daisuke Tashima ◽  
Eri Yamamoto ◽  
Nanami Kai ◽  
Daisuke Fujikawa ◽  
Go Sakai ◽  
...  
Keyword(s):  
Surface Area ◽  
Double Layer ◽  
High Surface ◽  
High Surface Area ◽  
Double Layer Capacitance ◽  
Carbon Nanospheres ◽  
Resorcinol Formaldehyde

Performance Study and Structure Control of Carbon Aerogel

2013 ◽  
Vol 706-708 ◽  
pp. 897-900 ◽  
Author(s):  
Rui He ◽  
Xuan Liu ◽  
Zhen Fa Liu ◽  
Li Hui Zhang
Keyword(s):  
High Surface ◽  
Sol Gel ◽  
Supercritical Drying ◽  
Carbon Aerogel ◽  
Preparation Condition ◽  
Carbon Aerogels ◽  
Performance Study ◽  
Structure Control ◽  
Sol Gel Process ◽  
Nanopore Structure

In this research the fabrication of carbon aerogel is reported. nanopore carbon aerogels were prepared via a sol-gel process with resorcinol and formaldehyde (RF) aerogels,which were cost-effectively manufacture form Rf wet gels by an ambient drying technique instead of conventional supercritical drying. The key of the work is to fabricate carbon aerogels with controllable nanopore structure, which means sharp pore size distribution and extremely high surface area.The influence of preparation condition of carbon aerogels was studied by scanning electron microscope and Micropore Physisorption Analyzer. The BET surface of the carbon aerogels are from 749m2/g to 1156m2/g .The size of the carbon nanoparticles are in the range of 20nm~40nm. The micro-pore volume and bore diameter can be controlled by gelation conditions such as RF mass fraction.

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