Abstract: The reaction mechanism of selective oxidation of ethanol on Au(111) covered with atomic oxygen was described employing density functional theory calculations. The first step, dissociation of the O–H bond in ethanol, has lower barrier for transfer of the H to adsorbed oxygen or surface hydroxyl than to gold with a barrier of 0.20 or 0.17 eV, respectively. The two lower activation energies for the β-H elimination of ethoxyl, 0.29 and 0.27 eV, come from transfer of H atom to surface O atom or another ethoxyl. Ethyl acetate is formed through the β-H elimination of ethoxy hemiacetal. The formation of acetic acid is not facile through the reaction between the surface hydroxyl and acetaldehyde or between the surface oxygen and acetaldehyde at low temperature due to a high activation barrier. Except for surface oxygen and bidentate acetate, all other surface species have low diffusion barriers, suggesting that rearrangement and movement of these species from the preferred adsorption sites to the ideal configurations for reactions are facile.

Key words: mechanism, selective oxidation, ethanol, Au(111) surface, density functional theory