Direct synthesis of Ru–Ni core-and-shell nanoparticles by spray-pyrolysis: Effects of temperature and precursor constituent ratio

Core-and-shell nanoparticles of Ru–Ni in the size range of 5–10 nm were synthesized by a single-step spray-pyrolysis process. Ruthenium chloride (RC) and nickel chloride (NC) were dissolved in water and used as a feed stream through an ultrasonic atomizer. The ruthenium chloride to nickel chloride (RC/NC) ratio was varied from 1:1 to 5:1 at various operating temperatures ranging from 500 °C to 1000 °C. Smooth core-and-shell nanoparticles were formed when the RC/NC ratio was 3:1 and 5:1 at 800 °C and 600 °C. A mechanism leading to the formation of such morphologies was proposed and was compared with the experimental results. It was found that as the RC/NC ratio in the precursor increased, temperature can be decreased to obtain core-and-shell nanoparticles. RC/NC ratio of 1:1 at low temperatures of 500 °C generated core-and-shell nanoparticles which are concentric rings. No core-and-shell morphologies were observed at temperatures higher than 800 °C. Once the core-and-shell particles are formed, the temperature can be varied in the range of 200 °C to cause a geometry change from core-and-shell to spherical nanoparticles.

Bimetallic nanoparticle of ruthenium and nickel with core-and-shell and diameter of 5–10 nm was synthesized by a single-step spray-pyrolysis process. The core consists mainly of ruthenium and the majority of the shell is nickel. It was demonstrated in the experiments that the atomic ratio of ruthenium chloride to nickel chloride and reaction temperature are critical to the formation of the core-and-shell structure.Figure optionsDownload as PowerPoint slide