STM investigation and Monte-Carlo modelling of spillover in a supported metal catalyst

✍ Scribed by A.J. Ramirez-Cuesta; R.A. Bennett; P. Stone; P.C.H. Mitchell; M. Bowker

• Book ID: 104421289
• Publisher: Elsevier Science
• Year: 2001
• Tongue: English
• Weight: 545 KB
• Volume: 167
• Category: Article
• ISSN: 1381-1169
• DOI: 10.1016/s1381-1169(00)00504-5

✦ Synopsis

Here we show, by in situ scanning tunnelling microscopy, that Pd nanoparticles enhance the rate of re-oxidation of a sub-stoichiometric TiO 2 (1 1 0) surface. We believe that O 2 dissociatively adsorbs at 673 K on the Pd, and "spills over" onto the support where further reaction takes place. Ti n+ interstitial ions in the bulk crystal lattice react with the spillover oxygen at the surface, preferentially growing TiO 2 around and over the particles. We employ a kinetic Monte-Carlo scheme to simulate this surface reaction and find a good correlation between the simulation and STM images. The simulation indicates that the surface structure may be reproduced in a model in which mobile species spillover from the metal particle, performs a random walk until it reaches a step edge where it may react (with low probability) to form TiO 2 . The mobile species may also down-step to a lower terrace but up-stepping is forbidden. The temporal evolution of surface structures from both experiment and simulation are compared.