Synthesis and characterisation of mesoporous carbons of large textural porosity and tunable pore size by templating mesostructured HMS silica materials

Abstract

Mesostructured HMS silica materials were used as templates to fabricate mesoporous carbons with a high textural porosity. The HMS silica samples were prepared in a water-rich neutral medium by using a primary amine as structure-directing agent. Materials prepared in this way, not only have a framework-confined porosity (structural), but also a large textural porosity resulting from the interparticle spaces between the primary particles. By varying the synthesis temperature of the HMS between 25 and 90 °C, and by aging the HMS sample synthesised at 50 °C between 90 and 140 °C it is possible to tune the size of the structural silica mesopores between 3.0 and 20 nm. As the synthesis temperature of the HMS silica increases over this range, the size of the structural mesopores of the templated carbons can be modified between 2.1 and 10.8 nm. The unique architecture of HMS silica template, which explains its large textural porosity, is reproduced in the templated carbon. Thus, the mesoporous carbons obtained as inverse replicas of HMS silica samples have large pore volumes (in the 1.8–3.5 cm 3 g −1 range), large BET surface areas of up to 2300 m 2 g −1, narrow pore size distributions (PSD) in the mesopore range and high textural porosities (∼50% of the pore volume corresponds to the interparticle volume). Moreover, templated carbons with a high textural porosity that have two structural pore systems made up of mesopores of different sizes can be achieved by varying the amount of carbon precursor allowed to infiltrate into the porosity of the silica.