Nanoscale casting using supercritical fluid

Porous silica fibers were synthesized by templating activated carbon fibers using supercritical fluid as a solvent. A precursor of silica, tetraethyl orthosilicate was dissolved in supercritical CO2 and attached to the base-activated carbon. The base-activated carbon in the sample coated with SiO2 was removed by calcination or O-2-plasma treatment. Not only the fibrous macro shape, but also the meso structure of the base-activated carbon fiber were faithfully replicated in the silica products. These results suggested the great advantage of supercritical fluid for fabricating ceramic replicates; of templates with complex structure, such as activated carbon. We have demonstrated that activated carbon with micropores acts not only as a mold for macroscopic shape control but also as a template for nanoscale structure control,:when a supercritical fluid was used as a solvent. The advantage of the supercritical fluid as a medium for replication is attributed to the inability of the supercritical fluid to produce a condensed phase.