First-Principles Calculations of the Effect of γ-Alumina Surface Hydroxyl Structures on the Location and Dechlorination of a Platinum Precursor.

The interaction between Pt precursors and alumina support is an important step in synthesizing Pt/Al 2 O 3 catalysts, while an in-depth understanding of the interaction is still lacking. Herein, density functional theory (DFT) calculations were performed to simulate the coordination of H 2 PtCl 6 with different surface hydroxyl groups, revealing the influence of the γ-Al 2 O 3 surface hydroxyl structure on the position of the Pt precursor and the removal of Cl ligands. After drying, the interaction mechanism between [PtCl 6 ] 2- and alumina support involves hydrogen bonds and van der Waals forces, which are the main driving forces for the structural transformation from [PtCl 6 ] 2- coordinated with the surface hydroxyl group into the PtCl x (OH) y species (OH is the γ-Al 2 O 3 surface group). HO-μ 1 -Al VI and H 2 O-μ 1 -Al VI on the (100) surface with electrophilicity facilitate hauling and activating the electron-rich [PtCl 6 ] 2- , but the nucleophilic (110) surface has a weaker interaction with [PtCl 6 ] 2- . Combining free energy and electronic property analysis, the stable structures on the (100) surface after drying treatment are PtCl 4 (OH) 2 and PtCl 3 (OH) 3 , while only PtCl 4 (OH) 2 structures can be formed on the (110) surface. This study can deepen our understanding of the interaction mechanism between Al-hydroxyl groups and Pt precursors, providing a theoretical reference for the precise placement of Pt active phases and the construction of metal-support interfaces.