Preparation and characterization of polypyrrole with dispersed metallic rhodium particles

摘要

Polypyrrole (PPy) with dispersed metallic Rh particles has been prepared by all-chemical route, i.e. reduction of Rh~(3+) ions existing in RhCl_3 aqueous solutions with sodium borohydride (NaBH_4) carried out in the presence of the previously obtained PPy doped with chloride ions (PPyCl). PPy-Rh composites thus formed have been characterized using X-ray diffraction (XRD), scanning and transmission electron microscopies (SEM, TEM) combined with energy dispersive X-ray (EDX) microanalysis, Rh3d X-ray photoelectron (XPS), and IR spectroscopies. This has made it possible to find out that metallic Rh nanoparticles, mainly of sizes below 10 nm, have been present in the composites. Agglomerates, with sizes up to 0.7 mm, have been formed in the systems containing higher amounts of Rh. PPy serving as the matrix in the composites has been doped. However, its doping level has been lower than that of the starting PPyCl. This has been explained by partial reduction of the polymer occurring during preparation of the composites. Catalytic properties of the PPy-Rh systems have been investigated using isopropyl alcohol conversion as a test reaction. It has been established that the composites are active redox catalysts. This makes them promising materials for applications as catalysts of various redox processes.