Methanol oxidation to CO or CO2 on Platinum surface goes through a small reaction intermediate of H:C:O stoichiometry. Here two forms of this reaction intermediate and the effects of water on their stability were studied on Pt(111) using density functional theory. Three cases were studied: the intermediate on a clean surface, the intermediate and one water molecule on the surface and the intermediate with a water bilayer. Both the H-C=O (formyl) and C-OH configurations were found to be stable on clean Pt(111) and when coadsorbed with a single water molecule. On the clean surface interconversion between the two forms goes through stable a COads and Hads intermediates so although both HCO and COH are stable on the clean surface they will not interconvert without coadsorbed water. In the presence of coadsorbed water molecule the activation barrier for the interconversion from HCO to COH was found to be much lower or 0.62 eV. The HCO configuration is stable in the presence of a water bilayer with slight preference for bridge over atop adsorption site. The energy barrier for COH -> CO +H in the presents of water is very small suggesting that COH would be unstable under the water bilayer and dissociates into COads and H. Various reactions paths for both of the reaction intermediates with OH and H2O eventually leading to CO or CO2 formation are also investigated.

Density functional theory study of stability and reactivity of H-C=O and C-OH reaction intermediates on Pt(111) and effects of water on the intermediates

247th National Meeting (2014)

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