Density Functional Theory Study of Methyl Iodide Adsorption and Dissociation on Clean and K-Promoted β-Mo₂C Surfaces

Abstract

ABSTRACT:We have studied the effect of K on the adsorption and dis sociation of methyl iodide on the β-Mo 2 C(001) surface using density functional theory calculations, and the results were compared with experimental data. The most favorable sites for methyl iodide adsorption are 3-fold sites on both clean and K-promoted surface. The changes in the work function fit our model as the molecule withdraws charge from the surface. The C-I bond weakens when the molecule adsorbs on the surface, and this effect is more noticeable on the K-promoted surface. The dissociation to an I adsorbed atom and a methyl group adsorbed is energetically favorable for both surfaces, but there is a lower activation barrier on the K-doped surface.

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

“…Although the reactions of different molecules on K-doped Mo 2 C surfaces were successfully modeled by our group with DFT calculations, resulting in reasonably well coincidence with experimental findings, − the detailed modeling of alkali modifier for CO interaction with Mo 2 C surfaces is still lacking. In the present work, the reaction pathway of CO decomposition in the presence of potassium on molybdenum- and carbon-terminated β-Mo 2 C single crystals is modeled using DFT.…”

Dissociative Hydrogen Adsorption on the Hexagonal Mo2C Phase at High Coverage

“…In addition to the experimental investigations, there are also theoretical studies on the catalytic properties of Mo 2 C. Liu et al − demonstrated the key role of the surface carbon atoms on the orthorhombic Mo 2 C in the catalytic dissociation of sulfur containing compounds based on density functional theory (DFT) calculations. Theoretical studies on the adsorption and decomposition of methanol, , methyl iodide, and CO as well as potassium promoting effect on the orthorhombic Mo 2 C were systematically reported by Pistonesi et al, and they found that the incorporation of potassium atoms enhances the dissociation ability of the C–I and C–O bonds in CH 3 I and CH 3 OH but increases the CO dissociation barrier.…”

Coverage dependent adsorption and co-adsorption of CO and H2 on the CdI2-antitype metallic Mo2C(001) surface

“…Due to their high importance in heterogeneous catalysis, there are many theoretical studies about the terminations, adsorption properties and reactions on the surfaces of the orthorhombic, [30][31][32][33][34][35][36][37][38][39][40][41][42][43][44] hexagonal eclipsed 26,[45][46][47] and hexagonal CdI 2 -antitype [48][49][50][51] structures. For understanding the catalytic properties of these individual structures we studied the fundamental aspects of these catalysts.…”