Preparation of Pt-nanoparticles-loaded carbon black catalysts by using Pt-carbonyl cluster complexes and their activity for oxygen reduction reaction

Abstract

Pt-carbonyl cluster complexes were prepared just by bubbling CO in various acetonitrile- or ethanol-water mixed solutions containing PtCl2-6. They had compositions of [Pt3(CO)3(CO) 3]n2- (n = 3-6) complexes in which a Pt 3(CO)3(CO)3 unit composed of triangular Pt atoms and two types of CO ligands was stacked. The number of Pt 3(CO)3(CO)3 units tended to decrease as water content in the mixed solutions increased. Pt nanoparticles prepared from the Pt-carbonyl cluster complexes had much smaller mean particle size (1.8-2.0 nm) and narrower size distribution (ca. 0.3 nm) than commercial ones. The Pt nanoparticles-loaded carbon black (Pt/CB) catalysts improved mass activity at 0.9 V for oxygen reduction reaction compared to the commercial catalyst (Pt/CBTKK). In particular, the mass activity for Pt/CB prepared from the [Pt3(CO)3-(CO)3]2-5-- complex produced in a water-ethanol mixed solution (water content: 50 vol. %) was ca. 1.7 times higher than that of the Pt/CB-TKK.