| Seeding and autocatalytic reduction of platinum and palladium salts in aqueous surfactant solutions using ascorbic acid as the reductant leads to remarkable metal nanostructures. In micellar surfactant solutions, spherical dendritic metal nanostructures are obtained, and the smallest of these nanodendrites resemble assemblies of joined nanoparticles and the nanodendrites are single crystals. With liposomes as the template, dendritic platinum and palladium sheets in the form of thin circular disks or solid foam-like nanomaterials can be made. Utilizing peptide nanotubes and vesicles as the template, platinized tubes and vesicles are obtained. Some synthetic control over the morphology of these nanodendrites, nanosheets, and nanostructured foams is realized by using a tinporphyrin photocatalyst to conveniently and effectively produce a large initial population of catalytic growth centers in the presence of different surfactant templating agents. In the solutions of micelles and liposomes, the concentration of seed particles determines the ultimate average size and uniformity of these novel nanostructures. The ligation states of the tin (IV) porphyrin photocatalyst involved in the synthesis are identified. |
