Stability of Pt10Sn3 Clusters Supported on γ-Al2O3 in Oxidizing Environment: a DFT Comparison of Alloying and Size Effects

The understanding of the structure and properties of gamma-Al2O3 supported platinum-tin catalysts in oxidizing conditions is of prominent importance for many catalytic reactions. By using density functional theory calculations and ab initio molecular dynamics simulations, we identify the adsorption sites of oxygen atoms on a Pt10Sn3/gamma-Al2O3(100) cluster model and analyze its reconstruction and electronic charge redistribution. A strengthening of O adsorption is found for the cluster with respect to the Pt3Sn(111) surface, due to the key role of Al-Pt interfacial sites at low coverage, the ductility and the metastability of the cluster. Moreover, the ab initio ( pO2 ${{p}_{{O}_{2}}}$ , T) thermodynamic phase diagrams show only minor differences between the supported Pt10Sn3 and Pt-13 clusters. Both clusters are much more oxidized than their homologous Pt and Pt3Sn(111) surfaces, and their oxygen contents may exceed 1 ML. This suggests a stronger size effect than an alloying effect for the oxidation of the metallic PtSn nanoparticles at small size.

Automated summary

Understanding the structure and properties of gamma-Al2O3 supported platinum-tin catalysts in oxidizing conditions is important for catalytic reactions. The study used density functional theory calculations and ab initio molecular dynamics simulations to investigate the adsorption sites of oxygen atoms on a Pt10Sn3/gamma-Al2O3(100) cluster model. The results showed that the cluster exhibited enhanced oxygen adsorption compared to the Pt3Sn(111) surface, and the oxidation of the clusters was primarily influenced by the size effect rather than alloying effect.