Formation of Ruthenium Nanoparticles by the Mixing of Two Reactive Microemulsions

Abstract

In this study, two reactants (ruthenium chloride and sodium borohydrate) were premicellized in two separate microemulsions and brought into contact through intermicellar exchange to conduct the reaction. As a result, ruthenium nanoparticles were formed. The overall reaction rate was governed by the intermicellar exchange rate. Particle size was controlled by varying surfactant concentration, water-to-surfactant molar ratio (ω), precursor (ruthenium chloride) concentration, and molar ratio of reducing agent-to-reagent (R). Dynamic light scattering and transmission electron microscopy were used to determine the size, size distribution, and structure of the synthesized ruthenium nanoparticles. The molar ratio ω was varied from 3 to 7; sizes of the particles were found to be in the range of 17.08–25.09 nm. The precursor (ruthenium chloride) concentration was varied in the range of 0.1–0.3 M; particle size was observed to decrease up to 0.2 M then increase due to particle agglomeration at higher precursor concentrations. Smaller nanoparticles were obtained at higher R values due to faster intramicellar nucleation and growth rate. Dispersion destabilization of colloidal ruthenium nanoparticles was detected by Turbiscan.