CHEMICAL SYNTHESIS AND CHARACTERIZATION OF NANOCRYSTALLINE PALLADIUM OXIDE

Growing interest in the synthesis of palladium oxide arises from its p otential use as a palladium precursor, for catalysis and as an electro de material. We report the preparation of palladium oxide by precipita tion from supersaturated aqueous solutions of Pd(NO3)(2) or PdCl2. The oretical modeling was carried out to ascertain the best yield of the r eaction with respect to the preparation conditions, i.e. temperature, pH and ionic strength, in the PdO-HCl-NH3-HNO3-NaOH-H2O system. Experi ments were performed in a batch reactor, and effects of the various pa rameters such as the reagent flow-rates or the aging time were studied . Microstructural characterization of the resulting powders shows that only hydrated palladium oxide PdO.xH(2)O is formed, with structural f eatures ranging from polymeric entities undetectable by Photon Correla tion Spectroscopy to porous aggregates containing 20 nm sized primary particles with varying degree of crystallinity. Reduction of the palla dium oxide in ethanol to produce metallic palladium is also briefly di scussed.