Nanoparticles of platinum and ruthenium supported on a wide variety of porous substrates including carbon aerogel, carbon black, silica aerogel, silica, g-alumina were synthesized via a supercritical fluid route. Organometallic precursors, dimethyl(1,5-cyclooctadiene)platinum (II) (PtMe₂COD) or bis(2,2,6,6-tetramethyl-3,5-heptanedionato)(1,5-cyclooctadiene) ruthenium (II) (Ru(cod)(tmhd)₂), were dissolved in supercritical carbon dioxide (scCO₂) and impregnated into the porous substrates. The impregnated organometallic precursors were converted to metal particles by a wide variety of methods which included thermal reduction and reduction by hydrogen at atmospheric pressure and in scCO₂. Reduction by hydrogen in scCO₂ led to the formation of metallic films whereas the three other techniques resulted in the formation of uniformly dispersed nanoparticles. The materials were characterized by a wide array of techniques including TEM, SEM, XRD and hydrogen chemisorption, The TEM pictures clearly indicated that the average particle sizes ranged from 1.2 nm to 6.4 nm and that the particle size distribution was very narrow in all cases. The particle size was found to increase with increasing reduction temperature and metal content and depended on the strength of the interaction between the organometallic precursor/metal and the surface. The technique was also used successfully used to disperse platinum and ruthenium nanoparticles in polymer electrolyte membranes.

If you'd like to meet with Prof. Erkey during his visit, please contact Meredith Leach (x4-2655 or leach at egr.uri.edu).