A DFT study on the formation of CH3O on Cu2O(111) surface by CH3OH decomposition in the absence or presence of oxygen

The formation mechanism of CH3O by the adsorption and decomposition of CH3OH on clean and oxygen-precovered Cu2O(1 1 1) surface has been investigated with density functional theory method together with the periodic slab models. Two possible formation pathways of CH3O by CH3OH decomposition on oxygen-precovered (O-pre) Cu2O(1 1 1) surface were proposed and discussed. One is the O-H bond-cleavage of CH3OH with H migration to Opre to form CH3O; the other is the C-O bond-scission of CH3OH with CH3 migration to Opre leading to CH3Opre. The calculated results show that the O-H bond-breaking path has the lowest activation barrier 26.8 kJ mol(-1), the presence of oxygen-precovered on Cu2O(1 1 1) surface exhibits a high surface reactivity toward the formation of CH3O by the O-H bond-cleavage of CH3OH, and reduce the activation barrier of O-H bond-cleavage. The C-O bond-breaking path was inhibited by dynamics, suggesting that the O atom of CH3O is not from the oxygen-precovered, but comes from the O of CH3OH. Meanwhile, the calculated results give a clear illustration about the formation mechanism of CH3O in the presence of oxygen and the role of oxygen at the microscopic level. (C) 2010 Elsevier B.V. All rights reserved.