Low-density organic and carbon aerogels from the sol–gel polymerization of phenol with formaldehyde

Wu, Dehai; Fu, Ruowen; Sun, Zhuoqi; Yu, Zhiquan

doi:10.1016/j.jnoncrysol.2005.02.008

Cited by 90 publications

(57 citation statements)

References 16 publications

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“…They show promising applicability as catalyst supports or energy storage media, such as fuel cell electrodes or supercapacitors, because of their unique electrical and structural properties [3][4][5][6]. However, GNFs have a quite low specific surface area of around 200-300 m 2 g −1 , compared with other porous catalyst supports, which is one of the main factors limiting their applicability [7].…”

mentioning

confidence: 99%

A study on pore-opening behaviors of graphite nanofibers by a chemical activation process

Kim

Lee

Park

2007

Journal of Colloid and Interface Science

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confidence: 99%

A study on pore-opening behaviors of graphite nanofibers by a chemical activation process

Kim

Lee

Park

2007

Journal of Colloid and Interface Science

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“…At that point, we have to be careful with the statements from literature, i.e. that PF links linearly in case of acid catalysis and cross-links upon alkaline catalysis [22,[33][34][35] and an excess of formaldehyde (F:P = 2-3) favours the possibility of cross-linking [16,22]. These schemes only hold on the molecular level (Angstrom), but not for the formation of a cross-linked 3-dimensional network of particles derived upon a sol-gel-transition, which takes place on a completely different scale (ca.…”

Section: Discussionmentioning

confidence: 99%

“…Although it was thought that pure phenol-formaldehyde mixtures would not be suitable for the synthesis of carbon gel precursors [13][14][15], three different research groups could show, that it is possible to synthesize phenol-formaldehyde (PF) based aerogels [16], cryogels [17] or xerogels [18,19].…”

Section: Introductionmentioning

confidence: 99%

Porous organic and carbon xerogels derived from alkaline aqueous phenol–formaldehyde solutions

2011

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Porous carbons were synthesized from the low cost precursors phenol and formaldehyde in aqueous solution, catalysed with NaOH. The xerogels were ambient pressure dried without prior solvent exchange. For an excess of formaldehyde, the resulting carbon xerogels show porosities up to 90%, with a predominant fraction of macroporosity, specific surface areas up to 768 m 2 /g and mesopore volumes up to 0.59 cm 3 /g. Small-angle X-ray scattering reveals fractal behaviour for many samples. Relevant sodium impurities up to 3-4 wt% in the organic and carbon samples cannot be avoided, even by washing of the samples. As possible reason for the high sodium content, the formation of crown ether like calix [6] arene is assumed. Overall, the sodium impurities detected confine the use of this system to applications, where higher ash contents are uncritical.

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“…Resorcinol and phenol are valuable precursors of carbonaceous solids. Phenol is less reactive than resorcinol but is cheaper [9][10][11]. Resorcinol, although expensive, presents several advantages for the preparation of gels.…”

Section: Introductionmentioning

confidence: 99%

Bimodal activated carbons derived from resorcinol-formaldehyde cryogels

Szczurek

Amaral-Labat

Fierro

et al. 2011

Science and Technology of Advanced Materials

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Resorcinol-formaldehyde cryogels prepared at different dilution ratios have been activated with phosphoric acid at 450• C and compared with their carbonaceous counterparts obtained by pyrolysis at 900• C. Whereas the latter were, as expected, highly mesoporous carbons, the former cryogels had very different pore textures. Highly diluted cryogels allowed preparation of microporous materials with high surface areas, but activation of initially dense cryogels led to almost non-porous carbons, with much lower surface areas than those obtained by pyrolysis. The optimal acid concentration for activation, corresponding to stoichiometry between molecules of acid and hydroxyl groups, was 2 M l −1 , and the acid-cryogel contact time also had an optimal value. Such optimization allowed us to achieve surface areas and micropore volumes among the highest ever obtained by activation with H 3 PO 4 , close to 2200 m 2 g −1 and 0.7 cm 3 g −1 , respectively. Activation of diluted cryogels with a lower acid concentration of 1.2 M l −1 led to authentic bimodal activated carbons, having a surface area as high as 1780 m 2 g −1 and 0.6 cm 3 g −1 of microporous volume easily accessible through a widely developed macroporosity.

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Low-density organic and carbon aerogels from the sol–gel polymerization of phenol with formaldehyde

Cited by 90 publications

References 16 publications

A study on pore-opening behaviors of graphite nanofibers by a chemical activation process

A study on pore-opening behaviors of graphite nanofibers by a chemical activation process

Porous organic and carbon xerogels derived from alkaline aqueous phenol–formaldehyde solutions

Bimodal activated carbons derived from resorcinol-formaldehyde cryogels

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