Novel synthesis of porous carbons with tunable pore size by surfactant-templated sol-gel process and carbonisation.

TL;DR: Surfactant-templated sol-gel polymerisation was explored to synthesize the resorcinol-formaldehyde gels without supercritical drying step, which were further carbonised to obtain porous carbons of a tunable pore size.

About: This article is published in Chemical Communications.The article was published on 2002-11-04 and is currently open access. It has received 77 citations till now. The article focuses on the topics: Supercritical drying.

Summary

T h i s j o u r n a l i s © T h e R o y a l S o c i e t y o f

• The pore size is primarily determined by the size of gel clusters, which is in turn controlled by the monomer/surfactant concentration.
• It is thus very likely that, in acidic conditions, the cross-linking between gel clusters becomes more facilitated to produce a more rigid gel network, and the pore collapse or shrinking at both the drying step and subsequent carbonisation step is suppressed.
• To test this possibility, the sol-gel polymerisation was performed at different pH by varying the R/F ratio in this work (samples C5-C7).
• When the pore properties are compared for samples C5-C7, there appears a strong correlation between the porosity and pH of the sol-gel medium even if the carbon cluster size is comparable for the three because the monomer/surfactant concentration is the same.
• Fig. 3(b) shows the pore size distribution of samples C3-C7 as calculated by the Barrett-Joyner-Halenda (BJH) method from the desorption branch of the isotherm.

Figures

Fig. 2 FE-SEM images of porous materials: (a) the RF precursor gel for C4 before carbonisation; (b) C4; (c) C2; (d) C5. The images were obtained with a JEOL JSM 6700F and 6330F. Note the uniform-sized spherical clusters and pores formed at the interstitial sites.

Fig. 1 The synthetic scheme for porous carbons. The detailed explanation is given in the text.

Frequently asked questions

Q1. What have the authors contributed in "Novel synthesis of porous carbons with tunable pore size by surfactant-templated sol–gel process and carbonisation" ?

Here, the authors report another low-cost preparation method for RF xerogels, where a normal drying is still applicable because the pore collapse can be minimized during the water evaporation. The microto nanosized spherical gel clusters are formed within the micelles, which are further three-dimensionally connected via a crosslinking reaction. The resulting RF gels are dried at 85 °C and further heat-treated at 1000 °C for 3 h under argon atmosphere to obtain porous carbons in monolithic shape.