日本ゼオライト学会　刊行物 Publication of Japan Zeolite Association

Various synthetic approaches for creation of mesoporous metals and the advantageous features are reviewed. Mesoporous metals have attracted increasing interests for many applications such as battery electrodes, fuel cells, electronic devices, catalysts, and so on. Mesoporous metals with highly ordered networks and narrow pore-size distributions have mainly been produced by using mesoporous silica as a hard template. This method is composed of two-step processes; (1) formation of a template such as mesoporous silica and (2) formation of metals within the mesopores and the following removal of the templates. Attard et al. have proposed "Direct Physical Casting" from lyotropic liquid crystals (LLC) made of non-ionic surfactants at high concentrations. This direct templated-synthesis created a novel avenue to the production of mesoporous metals as well as mesoporous silica. Many mesoporous metals have been prepared by chemical or electrochemcal reduction of metal salts dissolved in aqueous domains of LLC. LLC as a soft-template are more advantageous than hard-templates from the viewpoint of versatility. It is possible to produce various nanostructures such as lamellar, 2D-hexagonal (P6mm), 3D-cubic (la-3d), and nanotubes by controlling the compositions of reaction baths. We have expanded this original finding, and have synthesized mesoporous Ni, Pt, and Pt-Ni alloy as well as mesostructured Ni-Co with enhanced orderings by applying finely controlled metallization. Selective deposition of 2D-hexagonally ordered mesoporous Pt into microchannels has also been realized toward the practical applications.