A theoretical study of CHx chemisorption on the Ru(001)surface

The thermodynamics of methane decomposition on the ruthenium(0001) surface has been investigated with ab initio periodic calculations for coverages of 25% and 11%. All surface intermediates are more stable than the gas-phase methane even if the last step of the decomposition path (CH-> C + H) is highly endothermic. Amongst all of the surface species, CH appears to be the most stable, in agreement with experiments. All of the surface species (CH_x=3,0 and H) adsorb on three-fold sites. Short-range lateral interactions between CH_x=3,0 and H are also considered and are found to be mostly repulsive.