Preparation of rhodium nano-particles using microwaves

A new process for synthesizing rhodium (Rh) nano-particles by sol–gel processing using acrylamide and microwaves is reported and discussed. Three heat treatments were applied: the first required the use of microwaves, with an inert gas (Ar) flux, to decompose the organic material; the second and third treatments, respectively, were carried out into a furnace in air at temperatures of 600 and 1,000 °C. This procedure ensured the removal of by-products produced during the sol–gel reaction. The synthesis of a pure nano-Rh was confirmed by X-ray diffraction (XRD), where the presence of a cubic structure was observed (PDF file 089-7383), and EDX. Thermogravimetric analysis (TGA), in addition to determining the decomposition temperatures, enabled the heat treatment conditions needed to obtain pure nano- Rh to be elucidated. Furthermore, the morphology was observed with a scanning electron microscope (SEM). After the heat treatment at 1,000 °C, SEM images showed grain sizes between 3 and 200 nm. High-resolution transmission electron microscopy (HR-TEM) confirmed the production of those nano- particles, and the beginning of the formation of clusters as a consequence of the high temperature applied to the system.