Synthesis of Platinum-Ruthenium Alloy Nanoparticles on Carbon Using Supercritical Fluid Deposition

Platinum-ruthenium nanoparticles (Pt-Ru NPs) were deposited on carbon supports by using supercritical fluid deposition technique. In the present study, Ketjenblack and multiwalled carbon nanotubes (CNTs) were used as the carbon support. The deposition was carried out in a supercritical carbon dioxide solution from a mixture of a platinum complex and a ruthenium complex via hydrogen reduction. The obtained carbon/NP nanocomposites were characterized by using transmission electron microscopy and scanning transmission electron microscopy. Isolated crystalline fcc Pt-Ru NPs with diameters of approximately 2 nm were obtained. The density of the NPs increased with deposition temperature up to 423 K and then decreased above 423 K. The density of the NPs increased with deposition time up to 60 min and then decreased for longer deposition times. These tendencies indicate that NP nucleation occurs mainly at lower temperatures and/or with earlier deposition times, and agglomeration and coarsening become dominant at higher temperatures and/or with later deposition times. The density of the Pt-Ru NPs increased when the CNTs were pre-treated with hydrogen plasma. Roughening of the CNT surfaces was effective to achieve NP deposition with high density. (C) 2012 The Electrochemical Society. All rights reserved.