(452h) Formyl (HCO) Verses Hydroxymethylidyne (COH) Surface Intermediates on Pt(111)
Two forms of the reaction intermediate with H:C:O stoichiometry 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 water molecule. Interconversion between the two configurations was studied using the nudged elastic band method. On the clean surface interconversion between the two forms goes through a COads and Hads intermediate, meaning that although both HCO and COH are stable on the clean surface they will not interconvert. In the presence of coadsorbed water molecule the activation barrier for the interconversion from HCO to COH was found to be 0.62 eV. While the HCO configuration is stable in the presence of a water bilayer, the COH configuration dissociates to COads and Hads. These results suggest that, in the presence of water, the HCO form will be the only stable form of the reaction intermediate of H:C:O stoichiometry.