Platinum Metals Rev., 1997, 41, (4), 170
Hexagonal Nanostructured Platinum
Platinum particles can be prepared as nano-structures or monolayers, in polymers and in templates of ceramic materials by the reduction of platinum acids or salts. Researchers from the U.K. and Germany now report the use of a liquid-crystalline phase template to form nanostructured platinum (G. S Attard, C. G. Göltner, J. M. Corker, S. Henke and R. H. Templer, Angew. Chem. Int. Ed Engl ., 1997, 36, (12), 1315–1317).
Hexachloroplatinic acid and ammonium tetra-chloroplatinate were added to the surfactant, octaethyleneglycol monohexadecyl ether, which was used to prepare the lyotropic liquid-crystalline phases because it forms a wide hexagonal mesophase. The platinum salts were reduced, forming platinum powder of particle size 90 to 500 nm of hexagonal nanostructure with cylindrical pores 30 Å in diameter, separated by 30 Å thick platinum walls. The lyotropic phase may act as a structure-directing medium. Platinum is stabilised at the hydrophobic/hydrophilic interface as small colloidal particles which agglomerate and coalesce to a stable wall thickness. Only fast reductions allow tìiis structure to form before the liquid-crystal phase rearranges.
This nanostructured platinum is mesoporous and of large surface area – features useful for catalytic, fuel cell and sensor applications.