Surfactant-Mediated Synthesis of a Novel Nanoporous Carbon−Silica Composite

Abstract

A novel nanoporous carbon-silica composite with medium hydrophilicity is synthesized by a series of methods consisting of preexpansion of the interlayer of graphite oxide (GO) by surfactant intercalation, the intercalation of tetraethoxylsilane (TEOS) and its hydrolysis in the interlayer, followed by post carbonization to form a robust bridged/pillared network. High-resolution N 2 adsorption results show that carbonization at 823 K gives a composite having the highest specific surface area of more than 1000 m 2 /g with both microporosity and mesoporosity. Varieties of analytical results using DRIFT, NMR, XPS, and RAMAN spectra indicate that this composite contains small graphene sheets in its structure and its silicon components are silica particles with +4 valence. Morphology observation, thermal desorption, and other properties suggest the important roles of dispersion of GO in aqueous solution, preexpansion of GO interlayer, interlayer hydrolysis of TEOS molecules, and the carbonization condition in the formation mechanism of this nanoporous composite.

Pillared carbons consisting of silsesquioxane bridged graphene layers for hydrogen storage materials

“…8 shows the total storage capacity in a 1L container which was estimated based on the adsorbed and compressed hydrogen, the packing and helium densities, together with adsorbed hydrogen per volume. While i n t e r n a t i o n a l j o u r n a l o f h y d r o g e n e n e r g y 3 7 ( 2 0 1 2 ) 1 0 7 0 2 e1 0 7 0 8 the adsorbed hydrogen was 2e4 g/L, total storage capacity was in the range of 12e14 g/L, which was slightly smaller than that observed for activated carbons or zeolite templated carbon with much higher surface areas (less than 20 g/L) [9,23]. This is ascribed to the high packing density of the present pillared carbons.…”

Synthesis and Adsorption Characteristics of Nanoporous Graphite-Derived Carbon-Silica Composites

“…Furthermore, an unexpected larger V mi,loss value after step wn-1 is attributed to the loss of little part of mesopores which indicates existence of one part of ink-bottle-type pore structure with a neck of micropore size. In our previous report (Wang et al, 2003), porosities of another GOC 16 S-823 sample have been analyzed in detail by high-resolution α s -plot and the result on porosity change upon high temperature calcination suggests that microporosities and mesoporosities of the adsorbent are constructed of aggregates of small silica particles and the interstitial space between carbon layers and silica particles, respectively. The above pre-adsorption results, especially, the loss of microporosities due to water adsorption, strongly support this conclusion.…”

“…The graphite-derived nanoporous carbon/silica composite was synthesized by using an oxidized product of natural graphite as the precursor, whose method was detailed in the previous reports (Wang et al, 2003). Briefly speaking, commercial natural graphite was oxidized by Staudenmier's method (Staudenmaier, 1898) to give the graphite oxide (GO) product.…”

“…We have reported that nanoporous carbon/silica composites can be synthesized by hydrolyzing organic silicon alkoxides in the expanded interlayer of the oxidized product of graphite (Wang et al, 2002(Wang et al, , 2003. The obtained novel porous nanocomposite of carbon and silica has a very high surface area and presents a medium hydrophilicity between the typical activated carbon and hydrophilic silica particles.…”

Adsorption characteristics of nanoporous carbon–silica composites synthesized from graphite oxide by a mechanochemical intercalation method

“…In our previous paper, we have reported an effective soft-chemical route to obtain novel nanoporous carbon-silica composites from layered carbon precursor, graphite oxide (GO) [15][16][17]. The approach involves a series of colloidal and intercalation methods including GO layer delamination, layer pre-expansion with long chain surfactant, and interlayer hydrolysis of organic silicon species.…”