Reaction mechanism for CO oxidation on Cu(311): A density functional theory study

摘要

The microscopic reaction mechanism for CO oxidation on Cu(311) surface has been investigated by means of comprehensive density functional theory (DFT) calculations. The elementary steps studied include O_2 adsorption and dissociation, dissociated 0 atom adsorption and diffusion, as well as CO adsorption and oxidation on the metal. Our results reveal that O_2 is considerably reactive on the Cu(311) surface and will spontaneously dissociate at several adsorption states, which process are highly dependent on the orientation and site of the adsorbed oxygen molecule. The dissociated 0 atom may likely diffuse via inner terrace sites or from a terrace site to a step site due to the low barriers. Furthermore, we find that the energetically most favorable site for CO molecule on Cu(311) is the step edge site. According to our calculations, the reaction barrier of CO + O → CO_2 is about 0.3 eV lower in energy than that of CO + O_2 → CO_2 + O, suggesting the former mechanism play a main role in CO oxidation on the Cu(311) surface.