Development of polyol method for the synthesis of concentrated colloids of PVP-stabilised Ru nanoparticles

In the current work narrowly distributed and stable Ru nanoparticles (NPs) with mean diameters within 1.7 to 2.8 nm interval were prepared by reduction of RuCl3 with ethylene glycol (EG) as a solvent and a reducing agent as well as polyvinylpyrrolidone (PVP) as a stabiliser in the temperature range from 170 degrees C to 198 degrees C. Besides a typical polyol technique, Ru NPs synthesis using microwaves as well as sodium borohydride reduction at room temperature was applied as an effective alternative approach. The effect of heating conditions, Ru/PVP ratio, reducing agent and metal precursor concentrations on the particle size was studied. Microstructure of Ru NPs was characterised by UV-Vis, XPS and HRTEM. Higher PVP/Ru ratios and reduction temperature gave slightly smaller nanoparticles with narrower size distributions, while no clear effect was observed when the initial ruthenium concentration was varied.