Highly mesoporous carbons obtained using a dynamic template method

Abstract

New nanoporous carbons with extremely high mesopore volumes and surface areas were obtained using mesoporous silica with a 3-D wormhole porous framework as templates. Mesoporous silica was synthesized following the literature described methods. Polystyrene sulfonic acid-based organic salts were used as carbon precursors. To evaluate the effect of sodium on porosity development silica matrices with various thicknesses of pore walls were synthesized. Prior to carbonization, in order to increase surface heterogeneity, the precursor chemistry was modified by cation exchange with catalytically active metals (i.e., copper, nickel, cobalt). Carbonization followed by HF etching of silica templates generated mesoporous carbons with large surface areas and high pore volumes, which is accompanied by high dispersion of catalytically active metals on the carbon surface. Sodium present in the carbonaceous precursor causes in the dynamic template effect via its reactions with a silica matrix during carbonization. This, along with reactive gases evolved during heating lead to the expansion of the carbonaceous structure, and thus to the unique wide mesopore size distributions of the templated carbons with pore sizes between 10 and 50 nm and their volume exceeding 2.5 cm 3 g −1.