Ab-initio calculations of the direct and hydrogen-assisted dissociation of CO on Fe(3Â 1Â 0)

► CO dissociation on elemental iron surfaces. ► H-assistance to CO dissociation thermodynamically unfavourable on Fe(3 1 0). ► The more stepped the surface, the less viable H-assisted dissociation. ► The more close-packed the surface, the more stable CH + O (comparable to C + O + H).