Study of Platinum and Palladium Distribution in Advanced Materials Based on Tin Dioxide Using Inductively Coupled Plasma Mass Spectrometry (ICP-MS)

Abstract

Inductively coupled plasma mass spectrometry (ICP-MS) is used for separate determination of platinum and palladium on the surface and in the bulk of nanocomposites based on tin dioxide. Synthesis of SnO₂ matrices was conducted using deposition from solution and flame spray pyrolysis (FSP). The modifiers were injected by impregnation via the dispersion of the matrix powders in the solutions of precursors in volatile solvents and subsequent evaporation of the solvent. It is shown that palladium is present on the surface of the nanocomposites regardless of the synthesis procedure. As losses of the modifier after impregnation of SnO₂ synthesized by the FSP method are observed, we conclude that the properties of the SnO₂ surface depend on the method of obtaining the matrix. It is also shown that, for the materials obtained by the method of deposition from the solutions, 30–50% of Pt is present on the surface and other 50–70% is distributed in the bulk of SnO₂. The use of flame spray pyrolysis makes it possible to increase the content of Pt on the surface up to 80%. The loss of Pt observed in both cases and attributed to the differences in the microstructure of SnO₂ results in the etherification of thin layers of phases of complex composition which affect the processes of superficial diffusion and evaporation. Reproducibility of the results of Pt and Pd determination indicates a high degree of heterogeneity of the studied materials.