| Abstract
| - Supported nanoparticles of platinum on a wide variety of substrates, including carbon aerogel,carbon black, silica aerogel, silica, γ-alumina, and Nafion 112 film, were synthesized via asupercritical fluid route. The porous substrates and Nafion film were impregnated with anorganometallic precursor, dimethyl(1,5-cyclooctadiene)platinum(II) (PtMe2COD), from a supercritical carbon dioxide (scCO2) solution at 80 °C and 27.6 MPa. After depressurization, theimpregnated organometallic precursor was reduced to elemental platinum by heat treatmentin the presence of nitrogen gas. The resulting nanocomposites were investigated by transmissionelectron microscopy (TEM), which revealed uniformly dispersed platinum particles on each ofthe substrates with average particle sizes ranging from 1.2 to 6.4 nm and a narrow particle sizedistribution. A comparison of nanocomposites produced under different conditions showed thatboth the metal contents and the particle sizes are controllable.
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