Adsorption, diffusion and desorption processes of methanol on a Pt/TiO₂(110) model catalyst surface studied by STM and TPD

Abstract

We have examined adsorption, diffusion and desorption processes of methanol on a Pt/TiO₂(110) model catalyst surface by STM. Although methanol molecules were not dissociatively adsorbed on the perfect TiO₂(110) terraces at room temperature, they were dissociated at Pt nanoparticles to form methoxy species, which then spilled over to the substrate 5 fold-coordinated Ti sites (Ti_5c). They diffused along the [001] direction and also jumped to the next Ti_5c rows, but never go over the step edge. Their density gradually decreased when the surface was stored in UHV, whose rate increased as the density of Pt nanoparticles increased.