HREM study of strong-metal interaction in Pt/TiO2

Abstract

The chemisorption ability and catalytic properties of metal particles supported on reducible oxides are often altered by high temperature reduction(HTR) in a process known as strong metal-support interaction(SMSI). Different models have been proposed to explain the SMSI mechanism. In recent years, experimental evidences have favored the "decoration model", which suggests that SMSI is due to the encapsulation of the metal particles by oxide overlayer species dial have migrated from the support. HREM profile imaging was the most useful tool to directly relate these surface decorations to the SMSI effects. The profile imaging can provide atomic-scale information about supported particles and Uieir surfaces without image being obscured by overlapping contrast from the support.In the present work, the SMSI effect in Pt/TiO2 and Pt/CeO2 model catalysts have been studied using HREM profile imaging and multislice simulations. HREM observations were made with a JEM-4000EX microscope, operated at 400 kV. Fig. 1(a) shows a typical profile image of TiO2 after HTR in H2 at 923K.