Theory of Methane Dehydrogenation on Pt{110}(1 × 2). Part I:  Chemisorption of CHx(x= 0 −3)

The chemisorption of methane dissociation intermediates, CH x ( x = 0−3), on Pt{110}(1 × 2) has been investigated using calculations based on density functional theory. For all species considered, the most stable adsorption site identified on the missing-row reconstructed (1 × 2) surface is the site that not only completes the tetravalency of the carbon atom but also involves the maximum number of ridge Pt atoms for a site of that type. Thus, methyl (CH 3 ) preferentially occupies the ridge atop site; methylene (CH 2 ), the ridge bridge site; methylidyne (CH), the fcc 3-fold site on the {111} microfacet; and carbon, the pseudosubsurface 4-fold site at the bottom of the trough. A comparison of the relative stability of the chemisorbed CH x ( x = 0−3) species reveals that CH is the most stable dissociation intermediate on Pt{110}(1 × 2).