Supercritical CO2 as a solvent for synthesis of nanoporous materials

Nanoporous platinum, silica, and titania have been made using activated car bon templates in a supercritical solvent. Precursors were dissolved in supe rcritical carbon dioxide and attached to an activated carbon template. Afte r the activated carbon in the sample coated with materials was removed by c alcination or oxygen plasma treatment, samples faithfully that replicated n ot only macroscopic shape (e.g., fiber, powder, granule) but also porous st ructure on the nanometer scale were obtained. In addition, we confirmed tha t such a faithful reflection in the nanoscale structure is realized only by use of a supercritical fluid as a solvent, in comparison with impregnation in a liquid.