Theoretical Model for CO Adsorption and Dissociation on Clean and K-Doped β-Mo₂C Surfaces

We studied the effect of K on the adsorption and dissociation of CO on the β-Mo 2 C (001) surface by density functional theory calculations. Molecular CO adsorbs more strongly on Mo-terminated surfaces than on C-terminated 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.