Effect of synthesis pH on the structure of carbon xerogels
TL;DR: In this article, mesoporous carbon xerogels were prepared from the sol-gel polymerization of resorcinol with formaldehyde (RF) followed by carbonization.
About: This article is published in Carbon.The article was published on 1997-01-01. It has received 346 citations till now. The article focuses on the topics: Carbonization & Carbon.
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TL;DR: A brief overview on the preparation and properties of resorcinol-formaldehyde organic and carbon gels reveals very interesting features about their structural and performance characteristics as mentioned in this paper, which leads to a remarkable potential for designing and tailoring these materials to fit specific applications.
Abstract: A brief overview on the preparation and properties of resorcinol–formaldehyde organic and carbon gels reveals very interesting features about their structural and performance characteristics. The resulting nanostructure was very sensitive to the various synthesis and processing conditions. This leads to a remarkable potential for designing and tailoring these materials to fit specific applications. Based on step-by-step comparisons of the published studies, approximate generalizations on the specific roles the synthesis and processing conditions play on the final properties are provided. Overall, resorcinol–formaldehyde organic gels undergo two main stages during synthesis. The first stage is associated with the preparation of the sol mixture, and the subsequent gelation and curing of the gel. The second stage is associated with the drying of the wet gel. The most important factors that affect the properties of the organic gel during the first stage are the catalyst concentration, the initial gel pH, and the concentration of the solids in the sol. The most important factors that affect the properties of the organic gel during the second stage are the drying procedure (e.g., super- or subcritical drying), and the difference between the surface tensions of the solvent before and after drying. The corresponding resorcinol–formaldehyde carbon gels are produced from the organic gels during a third stage, which is associated with carbonization or activation. Depending on the conditions, carbonization and activation both impact the structural and performance characteristics significantly.
911 citations
TL;DR: In this paper, a review article summarizes the recent research progress on the synthesis of nanostructured carbon and its application in energy storage and conversion, and the common challenges in developing simple, scalable, and environmentally friendly synthetic and manufacturing processes, in controlling the nanoscale and high level structures and functions, and in integrating such materials with suitable device architectures are reviewed.
868 citations
TL;DR: In this article, a review examines methods of functionalizing porous carbon through direct incorporation of heteroatoms in the carbon synthesis, surface oxidation and activation, halogenation, sulfonation, grafting, attachment of nanoparticles and surface coating with polymers.
Abstract: Recent progress in syntheses of porous carbons with designed pore architecture has rejuvenated the field of carbon chemistry and promises to provide new advanced materials. In order to reap the full benefit of designer carbons, it is necessary to develop chemistries for functionalizing the porous carbon surfaces. This Review examines methods of functionalizing porous carbon through direct incorporation of heteroatoms in the carbon synthesis, surface oxidation and activation, halogenation, sulfonation, grafting, attachment of nanoparticles and surface coating with polymers. Methods of characterizing the functionalized carbon materials and applications that benefit from functionalized nanoporous carbons with designed architecture are also highlighted.
781 citations
TL;DR: Carbon aerogels and Cr-, Fe-, Co-, and Ni-containing carbon aerogel were obtained by pyrolysis, at temperatures between 500 and 1800 °C, of the corresponding carbon-airogels prepared by the sol−gel metho...
Abstract: Carbon aerogels and Cr-, Fe-, Co-, and Ni-containing carbon aerogels were obtained by pyrolysis, at temperatures between 500 and 1800 °C, of the corresponding aerogels prepared by the sol−gel metho...
436 citations
TL;DR: In this article, the pore texture of both dry and pyrolyzed carbon gels depends on the drying process, and several more or less expensive methods (supercritical drying, freeze-drying, evaporative drying) were tested in order to determine which process is the most suitable for the synthesis of a porous carbon with a definite texture.
420 citations
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01 Jan 1973TL;DR: CRC handbook of chemistry and physics, CRC Handbook of Chemistry and Physics, CRC handbook as discussed by the authors, CRC Handbook for Chemistry and Physiology, CRC Handbook for Physics,
Abstract: CRC handbook of chemistry and physics , CRC handbook of chemistry and physics , کتابخانه مرکزی دانشگاه علوم پزشکی تهران
52,268 citations
TL;DR: Mise au point comportant des definitions generales et la terminologie, la methodologie utilisee, les procedes experimentaux, les interpretations des donnees d'adsorption, les determinations de l'aire superficielle, and les donnes sur la mesoporosite et la microporosite.
Abstract: Mise au point comportant des definitions generales et la terminologie, la methodologie utilisee, les procedes experimentaux, les interpretations des donnees d'adsorption, les determinations de l'aire superficielle, et les donnees sur la mesoporosite et la microporosite
20,347 citations
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01 Jan 1990
TL;DR: In this article, the authors present and understand the sol-gel processing sequence from beginning to end, including discussions on the chemistry of hydrolysis and condensation of metal-organics and inorganic salts, the growth of polymeric or particulate species in sols, gelation, aging of gels, drying, structure of Gels, and sintering.
Abstract: Although the science and technology of sol-gel processing has experienced enormous growth in the last decade, few books have been available to help researchers cope with the flood of results published in various journals and conference proceedings. This book presents and understanding of sol-gel processing. Following the sol-gel processing sequence from beginning to end, it includes discussions on the chemistry of hydrolysis and condensation of metalorganics and inorganic salts, the growth of polymeric or particulate species in sols, gelation, aging of gels, drying, structure of gels, and sintering. In addition, it compares the properties of gel-derived and conventionally prepared ceramics, examines films in detail, and presents a variety of applications.
3,550 citations
TL;DR: In this paper, the polycondensation of resorcinol with formaldehyde under alkaline conditions results in the formation of surface functionalized polymer "clusters" which are processed under supercritical conditions to obtain low density, organic aerogels.
Abstract: The polycondensation of resorcinol with formaldehyde under alkaline conditions results in the formation of surface functionalized polymer “clusters”. The covalent crosslinking of these “clusters” produces gels which are processed under supercritical conditions to obtain low density, organic aerogels ( ⩽ 0.1 g cm−3). The aerogels are transparent, dark red in colour, and consist of interconnected colloidal-like particles with diameters of approximately 10 nm. The polymerization mechanism, structure and properties of the resorcinol-formaldehyde aerogels are similar to the sol-gel processing of silica.
1,603 citations