Methanol at the water-platinum interface studied by ab initio molecular dynamics

The adsorption and initial dehydrogenation of methanol on Pt(1 1 1) is examined using ab initio molecular dynamics. The simulations reveal that in solution the methanol molecule orientates with the CH3 group towards the surface, in contrast to the vacuum adsorption geometry. Our calculations also show that in vacuum the initial dehydrogenation step of CH3OH --> CH2OH + H has an energy barrier of only 0.45 eV, in good agreement with experimental results. We find a lowering and smearing of high-frequency hydrogen modes as a result of the methanol-surface interaction. The inclusion of hydration introduces additional effects and is necessary for a realistic treatment of the system. (C) 2003 Elsevier B.V. All rights reserved.