Synthesis, characterization, and catalytic application of Au/ZnO nanocomposites prepared by coprecipitation

In this study, Au/ZnO nanocomposites of different gold contents (0.8, 2.5, and 9%) and specific surface areas (from 41 to 51 m²/g) were synthesized via a coprecipitation method. The pure ZnO was obtained at the same experimental conditions. The samples were characterized by XRD, SEM, TEM, HRTEM, and XPS. The influence of gold nanoparticles (Au-NPs) loading on the catalytic activity of Au/ZnO nanocomposite was studied in the model reaction of CO oxidation. Spherical shape and homogeneous distribution of Au-NPs were observed in all samples prepared. The average size of Au-NPs in the obtained catalysts are almost the same (about 4 nm) allowing the studied effect to be manifested. The decrease of intrinsic catalytic activity of the coprecipitated Au/ZnO nanocomposites follows the sequence 2.5, 9, and 0.8% Au, as corresponding to the decrease of relative surface content of Au-NPs. It could be suggested that the catalytic activity is noticeably influenced by the distribution of Au-NPs between the bulk and surface of catalysts.