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

Abstract

A novel nanoporous C/SiO 2 composite was synthesized using graphite precursor by a soft chemical method and its adsorption properties were characterized by nonane, water, and nitrogen adsorption. It was found that only one part of micropores can strongly confine nonane molecules, indicating a wide micropore size distribution. Water adsorption leads to disappearance of one part of micropores, possibly due to closing of pores by dissociative adsorption of water on defective sites. Fractal analysis of the original and the differential nitrogen adsorption isotherms indicate that micropores have a rougher surface and mesopore a flatter surface, suggesting that micropores are surrounded by silica particles and mesopores involve the flat carbon layers.

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

“…The N 2 adsorption isotherms after water adsorption demonstrate a similar shape to those before water adsorption. However, the N 2 adsorption amounts decrease after water adsorption for the three samples, suggesting changes in porosities of these composites due to water adsorption (a result similar to those in the previous report [24]). Similar to the water and hexane adsorptions, the N 2 adsorption increases with an increase in the n value and becomes almost the same for the samples with n = 6 and 22.…”

“…Consequently, the V Total,0.95 values do not dramatically change before and after water adsorption. Analysis using high-resolution α s -plot, pre-adsorption, and fractal techniques on N 2 adsorption in our previous results suggested that microporosity and mesoporosity of the carbon-silica composites synthesized by the ordinary method come from the interstitial spaces between aggregates of small silica particles and those between carbon nanosheets and silica particles, respectively [16,24]. Accordingly, we can conclude from the above discussion that more silica particles with smaller sizes can be formed between carbon layers when the n value for the synthesis increases from 1 to 6 and 22, enhancing the amount of micropores.…”