Preparation of Tractable Platinum, Rhodium, and Ruthenium Nanoclusters with Small Particle Size in Organic Media

In the absence of any usual protective agent, stable platinum, rhodium, and ruthenium metal nanoclusters with small particle size in organic media are effectively prepared by heating corresponding metal hydroxide colloids in ethylene glycol containing NaOH for the first time. The average diameters of the Pt, Rh, and Ru nanoclusters determined by means of transmission electron microscopy are in a range from 1 to 2 nm. The particle size distribution in each colloidal solution is sharp, within 2 nm wide. Studies on the preparation conditions and some properties of the "unprotected" Pt metal nanoclusters have been carried out. By adjusting pH, it is convenient to separate the Pt nanocluster as a precipitate from glycol solvent, and the precipitated Pt nanoclusters can easily be "dissolved" in many organic solvents to form transparent Pt nanocluster solutions with high concentration in the absence of usual protective agents. The "unprotected" Pt nanoclusters can also be easily transformed to various protected Pt nanoclusters with the same Pt cores and can be extracted into toluene by forming PPh3-modified Pt clusters.