GO-STABILIZED SUPPORTED PT CATALYSTS FOR FUEL-CELLS - RADIOLYTIC SYNTHESIS

In a CO-saturated water/2-propanol mixed solvent, K2PtCl4 salt can be radiolytically reduced either into molecular carbonyl clusters of the [Pt-3(CO)(6)](2-)(n) series or into colloidal metal particles by varyi ng the CO:Pt ratio, The reduction occurs by a combined effect of CO an d radicals produced by radiolysis, giving rise to unusually high reduc tion yields, The colloidal platinum and also the molecular clusters ca n easily be impregnated on carbon black, The particle size of the supp orted catalyst prepared in this way lies in the 2-3 nm range and is in dependent of the catalyst loading and support surface area, even for h igh loadings (3-nm particles have been deposited up to a 60 wt% loadin g on a Printer powder), These catalysts are found to be efficient for methanol or hydrogen electrooxidation and for oxygen electroreduction. The CO-stabilized colloids have been characterized by electron micros copy and UV-visible spectroscopy, (C) 1996 Academic Press, Inc.