The effect of surfactants on the porosity of carbon xerogels

Abstract

Mesoporous carbon xerogels were prepared from the sol–gel polymerisation of resorcinol (R) with formaldehyde (F) followed by carbonisation. A xerogel with high mesoporosity was obtained after synthesis at pH 6.4 and carbonisation at 800 °C, during 3 h. During the synthesis of the gel, three different surfactants (non-ionic, cationic and anionic) with concentrations varying between 0.1% and 15% (wt./wt.) were used. The carbon xerogels obtained showed that addition of surfactants affects the porous structures of the carbon xerogels. The addition of non-ionic surfactant does not influence the morphology and porous size distribution. In contrast, anionic and cationic surfactants have an important role on pore size distribution. The addition of cationic surfactant increases the pores size (2–25 nm) and the size of carbon particles. Anionic surfactants promote larger mesopore size (2–40 nm and larger than 80 nm) and a bimodal mesopore size distribution. By using different surfactant concentrations, it is possible to tailor carbon xerogels for specific applications.