Dithiocarbamate-protected ruthenium nanoparticles: Synthesis, spectroscopy, electrochemistry and STM studies

Stable ruthenium nanoparticles were synthesized in a biphasic system with a protecting monolayer of dithiocarbamate derivatives. The core ize of the resulting Ru particles was found to vary with the initial ligand–metal feed ratio. UV–vis spectroscopic measurements showed a Mie cattering profile, with no obvious surface-plasmon resonance. The size and crystal structures of the particles were characterized by transmission lectron microscopic (TEM) measurements. A significant fraction of the nanoparticles was found within the size range of 2–4 nm in diameter and f spherical shape from the TEM measurements. Clear lattice fringes could be observed in high-resolution TEM images with the fringe spacing onsistent with the Ru(1 0 1) lattice planes. Electrochemical studies of Ru particles with different core size exhibited the solution-phase quantized harging of the particle double layers, analogous to those reported for gold and other transition-metal particles. The potential spacing between djacent quantized charging peaks was found to vary with the particle core size, corresponding to the variation of the particle molecular capacitance. hese charge-transfer properties were very consistent with the STM measurements of isolated nanoparticles which exhibit clear Coulomb blockade nd staircase features. 2007 Published by Elsevier Ltd.