Nanoporous Silica Prepared with Activated Carbon Molds Using Supercritical CO₂

Nanoporous silica materials have been prepared using an activated carbon as a mold and supercritical carbon dioxide as a solvent. Tetraethyl orthosilicate (TEOS) dissolved in supercritical carbon dioxide was in contact with the activated carbon templates of various macroscopic shapes (fibers, granules, powders). After the removal of activated carbon templates by calcination in air or oxygen plasma treatment, microporous and mesoporous silica samples replicating not only mesostructures, but also macroscopic shapes, of activated carbon molds were obtained. The pore size of the silica replicas increases with increase in carbon crystallite size of activated carbon as estimated from XRD patterns.