Highly Efficient MCM-48-based Template Synthesis of Osmium and Platinum 3-D Nanonetworks

We have utilized the facile capillary action of MCM-48 template toward molten organometallic precursors to prepare networked metal 3-D nanostructures. The simple experimental procedure and availability of numerous organometallic precursors with similar decomposition behaviors would make this capillarity-based template synthesis a very promising method for the preparation of various functional mesoporous metals. Nanostructured materials have attracted a great attention because of their novel size- and shape-dependent electronic, magnetic, optical, and catalytic properties that differ drastically from those of bulk materials. Metals of nanosize, in particular, are expected to find useful applications in catalysis due to high surface area, and some results using nanoparticles as catalysts were reported. Ni/Pd core/shell nanoparticles show good catalytic activities in Sonogashira coupling reactions, and Pd nanoparticles with chiral ligands are good catalysts for asymmetric catalyses. These nanoparticles contain ligands on their surface, thus possessing very good solubilities in organic solvents. The improved solubility of nanoparticles, however, can impede facile recovery of the catalysts after reaction. Hyeon et al. reported the preparation of micron-sized hollow palladium spheres composed of bare nanoparticles without surfactants and these materials showed excellent catalytic activities in Suzuki cross coupling reactions and a good recoverability, thus calling for further extensive studies on designed 3-D nanostructures of other metals for efficient catalyses and facile catalyst recovery processes