Density Functional Theory Study of H and CO Adsorption on Alkali-Promoted Mo₂C Surfaces

Using alkali metals as promoters is known to strongly influence the selectivity of catalytic reactions on Mo 2 C catalysts. To provide fundamental information about this observation, density functional theory calculations have been performed to study K and Rb adsorption of seven low-index α-Mo 2 C surfaces and the equilibrium crystal shape of Mo 2 C has been predicted using the Wulff construction. K and Rb are found to bind most strongly on Mo 2 C (001). This surface is also shown to favor a reconstruction in the absence of adsorbates. This reconstruction strengthens the adsorption of K and H while it weakens the adsorption of CO on the surface. A small number of calculations of H/K and CO/K coadsorption were performed to probe the effect of alkali promoters on these adsorbed species.