Role of PdO_<i>x</i> and RuO_<i>y</i> Clusters in Oxygen Exchange between Nanocrystalline Tin Dioxide and the Gas Phase

Abstract

The effect of palladium- and ruthenium-based clusters on nanocrystalline tin dioxide interaction with oxygen was studied by temperature-programmed oxygen isotopic exchange with mass-spectrometry detection. The modification of aqueous sol–gel prepared SnO₂ by palladium and, to a larger extent, by ruthenium, increases surface oxygen concentration on the materials. The revealed effects on oxygen exchangelowering the threshold temperature, separation of surface oxygen contribution to the process, increase of heteroexchange rate and oxygen diffusion coefficient, decrease of activation energies of exchange and diffusionwere more intensive for Ru-modified SnO₂ than in the case of SnO₂/Pd. The superior promoting activity of ruthenium on tin dioxide interaction with oxygen was interpreted by favoring the dissociative O₂ adsorption and increasing the oxygen mobility, taking into account the structure and chemical composition of the modifier clusters