Theoretical Model for CO Adsorption and Dissociation on Clean and K-Doped β-Mo 2 C Surfaces

Abstract

We studied the effect of K on the adsorption and dissociation of CO on the B-Mo2C (001) surface by density functional theory calculations. Molecular CO adsorbs more strongly on Mo-terminated surfaces than on Cterminated ones. Adsorption is energetically more favorable in the presence of preadsorbed potassium. The CO molecule withdraws electron density from the surface, being more extended on the K-doped surface. The CO dissociation was also evaluated, and reaction pathways were modeled, revealing that the C-terminated surface is energetically less favorable than the Mo-terminated one. For both surfaces, the activation energy barrier for dissociation increases with the K content. C-O vibrational frequencies were also computed on K-modified surfaces.