LAUSR

Abstract Adsorption and sequential decomposition of ammonia on the metallic Mo 2 C(001) surface have been systematically computed using periodic density functional theory under the consideration of van der Waals dispersion correction (PBE-D3). It is found that NH 3 adsorption prefers the top sites from low to saturation coverage. For the adsorption of surface NH 2 , bridge and hollow sites are possible at low coverage and only bridge sites are preferred at high coverage up to saturation. The adsorption of surface NH and N prefers the hollow sites. Sequential decomposition of NH 3 into surface NH 2 , NH and N has low barrier and is highly exothermic. On the basis of surface Mo atoms, the saturation coverage of surface NH 3 , NH 2 , NH and N by using NH 3 as nitridation agent is 0.75, 1.0, 1.0 and 0.5 monolayer, respectively. These results provide the basis for the study of surface properties and catalytic reaction of nitrided Mo 2 C surfaces. The dissociative adsorption of ammonia among others metals and molybdenum nitrides has been categorized and compared.