(745d) Ab-Initio Study of the Interface between g-Al2O3 and Pt

Interfaces between metals and metal oxides occur in heterogeneous catalysis where metal catalyst nanoparticles are dispersed on highly porous metal oxide supports to increase the surface area. The interactions between catalyst nanoparticles and the catalyst support has previously been shown to affect both the overall activity and selectivity of the catalyst. Being able to describe and predict the structure of the catalyst, the catalyst support and the interface between the two is therefore a critical step towards understanding the catalyst-support interactions. γ-Al₂O₃ is a commonly used catalyst support due to its durability at operation conditions and high surface area, which makes it suitable for the efficient dispersal of metal catalysts. In this work, theoretical and experimental methods are combined to investigate and predict the structure and thermodynamic stability of the interface between γ-Al₂O₃ and Pt nanoparticles. The experimental approach involves the fabrication of the embedded Pt nanoparticles and the use of high resolution transmission electron microscopy (HRTEM) to image the structure. The theoretical approach utilizes density functional theory (DFT) to calculate the interfacial energies of Pt(111) and three different terminations of the g-Al₂O₃ (111) surface plane. Of the three interfacial terminations, Pt atoms interacting with oxygen terminated γ-Al₂O₃ (111) are the most stable interfaces at atmospheric conditions. The stability of this interface is based on the strong electrostatic interaction between the Pt atoms and the oxygen atoms at the oxygen terminated interface. This work provides the complement to experimental study of the atomic structure of the interface between γ-Al₂O₃ and Pt nanoparticles.