The preparation of chromium, nickel and chromium–nickel alloy nanoparticles on supports

Abstract

Chromium, nickel and chromium–nickel alloy nanoparticles have been synthesised via the addition of a metal salt solution to a support, followed by drying and reduction with hydrogen at elevated temperatures. Chromium and chromium–nickel alloy particles were prepared using ethylene glycol solutions and were found to be stable on silica and baddeleyite (ZrO₂) supports. The crystal structures adopted were investigated using high resolution electron microscopy (HRTEM) and found to be similar in both cases to the bulk metal and alloy. The particle morphology, also from HRTEM observations, was found to be pseudo-spherical. Nickel nanoparticles could be formed using an aqueous solution on a variety of supports and were found from powder X-ray diffraction (PXRD) and HRTEM data to adopt the face-centred cubic structure of the bulk metal. The effect of different supports on the average particle size was investigated with PXRD and the particle morphology with HRTEM. The supports were found to have little effect on the average particle size, but had a noticeable influence on morphology, with particles on alumina being found to be flat and angular in contrast to those on graphitised carbon and ceria, which had pseudo-spherical morphologies.