Adsorption in Sparse Networks

Scherer, George W.; Calas, S.; Sempéré, R.

doi:10.1006/jcis.1998.5459

Cited by 18 publications

(14 citation statements)

References 14 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The increase of V p is compatible with the increase of characteristic size x of the fractal cluster as observed by SAXS (Table 1), because as larger is the quantity of SDS micelles, larger are the spaces filled by the surfactant during the earlier gelation process, increasing the pore volume and the fractal cluster size. The apparent discrepancy in V p found in the sample with C R ¼ 100 (V p was unexpectedly found smaller in this sample with respect to other samples prepared with SDS) could be explained because conventional nitrogen adsorption can underestimate the pore volume in a sparse silica network, since the adsorbate/vapor interface can adopt a surface of zero curvature while much of the larger pores remains empty [31,32]. The extent of the phenomenon is larger as larger the pore/particle size ratio, Fig.…”

Section: Nitrogen Adsorptionmentioning

confidence: 73%

“…The lower rate of diminution of r N2 compared to r x with increasing the SDS quantity (and the abnormal high value found for r N2 in the sample with C R ¼ 100) could be explained because the underestimating of the pore volume by nitrogen condensation in sparse silica networks [31,32], as mentioned earlier, is larger as larger the pore/particle size ratio, which was expected to be larger in APD aerogels prepared with higher SDS quantities, particularly for the sample with C R ¼ 100. The bulk densities r gly were found not too dependent on the SDS quantity, presenting a typical value of about 0.20 g/cm 3 (Table 4), which is about 30% smaller than the typical values found for r x and r N2 .…”

Section: Saxs and Nitrogen Adsorption Correlation Datamentioning

confidence: 99%

See 1 more Smart Citation

Structure and diffuse-boundary in hydrophobic and sodium dodecyl sulfate-modified silica aerogels

Perissinotto

Awano

Vicente

et al. 2016

Microporous and Mesoporous Materials

View full text Add to dashboard Cite

a b s t r a c tSmall-angle X-ray scattering (SAXS) and nitrogen adsorption were used to study ambient pressure drying (APD) silica aerogels prepared from hydrolysis of tetraethoxysilane (TEOS) with additions of sodium dodecyl sulfate (SDS). The surfactant-extracted precursor wet gels have presented mass-fractal structure with typical fractal dimension 2.25 in a SAXS characteristic length scale from~10 nm to~0.35 nm. Hydrophobic APD aerogels with typical specific surface of 800 m 2 /g and bulk density of 0.20 g/cm 3 were obtained after silylation of the precursor wet gels with a mixture of hexamethyldisiloxane (HMDSO) and trimethylchlorosilane (TMCS). The pore volume and the mean pore size of the APD aerogels increased with increasing the SDS quantity. APD aerogels presented most of the mass-fractal characteristics of the precursor wet gels at large length scales. The radius of gyration of the clusters of the APD aerogels (typically 17 nm) increased with increasing the SDS quantity, while the radius of the silica primary particles (typically 2.0 nm) increased at first with the addition of SDS (with respect to the sample without SDS) and decreased regularly afterward with increasing the SDS quantity. The primary particles presented yet some internal inhomogeneity and a diffuse-boundary interface with thickness of about 0.7 nm, according to a linear-gradient model for the diffuse boundary.

show abstract

Section: Nitrogen Adsorptionmentioning

confidence: 73%

Section: Saxs and Nitrogen Adsorption Correlation Datamentioning

confidence: 99%

Structure and diffuse-boundary in hydrophobic and sodium dodecyl sulfate-modified silica aerogels

Perissinotto

Awano

Vicente

et al. 2016

Microporous and Mesoporous Materials

View full text Add to dashboard Cite

show abstract

“…However, there is no article on the application of SiO 2 aerogels as supercapacitors. SiO 2 aerogels possess structural advantages for electrochemical energy storage as follows: (1) high surface areas (>500 m 2 g −1 ), which amplify the amount of electrifiable interface [7][8][9]; (2) mesoporosity, which provides both molecular accessibility and rapid mass transport via diffusion [7,[9][10][11][12][13]; (3) a threedimensional network of nanometer-sized solid particles, which promotes efficient electronic conduction [9,10]; and (4) nanoscale particle sizes, which minimize solid-state transport distances for ion-insertion reactions [9,13]. Based on these features, SiO 2 aerogels can be a desirable material for supercapacitors in organic electrolyte.…”

Section: Introductionmentioning

confidence: 99%

Studies on the performances of silica aerogel electrodes for the application of supercapacitor

Wang

et al. 2009

Ionics

View full text Add to dashboard Cite

Silica aerogel (SiO 2 aerogel) was prepared by solgel method from tetraethyl orthosilicate hydrolyzation and has been characterized by scanning electron microscopy and N 2 adsorption for its surface structure, surface area, and poresize distribution. Constant current charge-discharge technique, cyclic voltammetry, and electrochemical impedance spectrum were employed for its specific capacitance and equivalent series resistance. The results showed that the maximum specific capacitance of SiO 2 aerogel electrode in 1 M Et 4 NBF 4 /PC electrolyte was 62.5 F g −1 . In addition, the SiO 2 aerogel capacitor exhibits excellent long-term stability with no significant degradation after 500 charging and discharging cycles. Therefore, the application of high surface area SiO 2 aerogel as electrodes in supercapacitor devices is promising.

show abstract

“…Since an intense investigation of aerogels started in the 1980s, nitrogen adsorption and desorption (NAD) has been applied to this class of porous materials to determine specific surface areas and pore size distributions (e.g., (1)(2)(3)(4)(5)(6)(7)). While the surface areas extracted from NAD generally are consistent with data derived via other methods (e.g., SAXS (8) and TEM (9)), the total pore volume significantly failed to be fully detected for samples with porosities above 85 to 90% (10).…”

Section: Introductionmentioning

confidence: 99%