Highly Stable Bimetallic AuIr/TiO₂ Catalyst: Physical Origins of the Intrinsic High Stability against Sintering.
It has been a long-lived research topic in the field of heterogeneous catalysts to find a way of stabilizing supported gold catalyst against sintering. Herein, we report highly stable AuIr bimetallic nanoparticles on TiO2 synthesized by sequential deposition-precipitation. To reveal the physical origin of the high stability of AuIr/TiO2, we used aberration-corrected scanning transmission electron microscopy (STEM), STEM-tomography, and density functional theory (DFT) calculations. Three-dimensional structures of AuIr/TiO2 obtained by STEM-tomography indicate that AuIr nanoparticles on TiO2 have intrinsically lower free energy and less driving force for sintering than Au nanoparticles. DFT calculations on segregation behavior of AuIr slabs on TiO2 showed that the presence of Ir near the TiO2 surface increases the adhesion energy of the bimetallic slabs to the TiO2 and the attractive interactions between Ir and TiO2 lead to higher stability of AuIr nanoparticles as compared to Au nanoparticles.
Chang Wan
CW
Han
Paulami
P
Majumdar
Ernesto E
EE
Marinero
Centro de Ciencias Aplicadas y Desarrollo Technologico, Universidad Nacional Autonoma de Mexico , Mexico City 04510, Mexico.
Antonio
A
Aguilar-Tapia
Centro de Ciencias Aplicadas y Desarrollo Technologico, Universidad Nacional Autonoma de Mexico , Mexico City 04510, Mexico.
Rodolfo
R
Zanella
Jeffrey
J
Greeley
Volkan
V
Ortalan
Heterogeneous catalysts; aberration-corrected transmission electron microscopy; bimetallic catalyst; density functional theory; stability of gold catalysts