Synthesis and Description of Small Gold and Palladium Nanoparticles on CeO2 Substrate: FT- IR Spectroscopy Data

Abstract

Palladium (Pd/CeO2), gold (Au/CeO2), and bimetallic (PdAu/CeO2) nanoparticles obtained via impregnation of the surface of cerium dioxide with tetraethylene pentamine and subsequent reduction in a H2/Ar flow are synthesized and described. The particles possess a high degree of dispersion, but their small size complicates their analysis with conventional methods (transmission electron microscopy and X-ray powder diffraction). Diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) combined with CO sample molecules is used to study the size and morphology of the nanoparticles and the substrate. The intensity ratios of the bands assigned to bridge and linear carbonyls at palladium centers indicate that there are finely divided nanoparticles in the case of a monometallic sample and larger nanoparticles in the case of a bimetallic one. The resulting materials have high catalytic activity and stability: the complete conversion of CO for Pd/CeO2 is achieved at about 50°C. We find that the catalytic activity of the samples decreases in the series Pd/CeO2–Au/CeO2–PdAu/CeO2, which indicates that there is no synergistic effect in the case of a bimetallic sample.