Density functional theory study into the adsorption of CO2, H and CHx (x = 0-3) as well as C2H4 on α-Mo2C(0 0 0 1)

The structures and energetics of the chemisorbed CO2, CHx species and H as well as C2H4 on the α-Mo2C(0 0 0 1) surface have been computed at the GGA-RPBE level of density functional theory. It is found that CO2 adsorbs dissociately into CO and O, in agreement with the experimental finding. The adsorbed O, CHx and H species prefer the site of three surface molybdenum atoms over a second layer carbon atom (VC site). On the basis of the calculated adsorption energies of CHx and H, the sequential dehydrogenation of CH4 and the C/C coupling reaction of CHx have been discussed.