High-power pulsed gas-flow sputter synthesis of nanoparticles, core/shell nanoparticles, and extended chain-like complexes

Nanoparticles play an important role in many industrial applications. Therefore, the development of new complex nanoparticles, and the methods for their synthesis, are very important research topics. Complex nanoparticles, including core/shell, core/satellite, composition gradient and Janus particles, can be designed to obtain a wide range of novel properties. The pulsed hollow cathode plasma-based method used in the present work is very flexible and can grow heterogenous particles from any combination of materials that can be sputtered and can be used in combination with reactive gases. The method is unique in that close to full ionization of the source material is achieved through the very high plasma-density achieved. The ionization leads to a high rate of material entrapment on the growing nanoparticles reducing the material loss to a minimum. In this presentation the method is exemplified by Ni/Pt alloys and Ni/Pt core/shell nanoparticles assembled into nanowires for use as electrodes in hydrogen generation. As an example, Ni nanoparticles (50 nm in diameter) are coated with Pt shells of controlled thickness in the 1-3 nm range.