Pt/Au nanoalloy supported on alumina and chlorided alumina: DFT and experimental analysis

Density functional theory (DFT) was used to explore the adsorption of Pt/Au nanoalloy onto a pure and chlorided γ-Al₂O₃(110) surface, which has been applied in numerous catalytic reactions. First, we considered the adsorption properties of Pt clusters (n ≤ 5) onto the Al₂O₃(110) surface to determine the most stable Pt cluster on alumina surface in reforming processes. After full structural relaxations of Pt clusters at various configurations on alumina, our computed results expressed that the minimum binding energy (−5.67 eV) is accrued for Pt₄ cluster and the distance between the nearest Pt atom in the cluster to the alumina surface is equal to 1.13 Å. Then, we investigated the binding energies, geometries, and electronic properties of adsorbed Au_n clusters (n ≤ 6) on the γ-Al₂O₃(110) surface. Our studied showed that Au₅ was the most thermodynamically stable structure on γ-Al₂O₃. Finally, we inspected these properties for adsorbed Au clusters onto the Pt₄-decorated alumina (Au_n/Pt₄-alumina) system. The binding energy of the Au₄/Pt₄-alumina system was −5.01 eV, and the distance between Au₄ cluster and Pt₄-alumina was 1.33 Å. The Au₄/Pt₄alumina system was found to be the most stable nanometer-sized catalyst design. At last, our first-principles calculations predicted that the best position of embedment Cl on the Au₄/Pt₄-alumina. (paper)