Theory of methane dehydrogenation on Pt{110}(1x2).: Part 1:: Chemisorption of CHx (x=0-3)

The chemisorption of methane dissociation intermediates, CHx (x = 0-3), on Pt{110}(1 x 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 x 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 (CH3) preferentially occupies the ridge atop site; methylene (CH2), 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 CHx (x = 0-3) species reveals that CH is the most stable dissociation intermediate on Pt{110}(1 x 2).