Beneficial effect of Au and Pt doping of the Ag-(100) surface for thiophene and pyridine adsorption from density functional theory calculations

We use density functional theory including van der Waals (vdW) interactions to investigate the adsorption of thiophene (C4H4S) and pyridine (C5H5N) on the Ag-(100) surface doped by Pt, Au, Pt2, Au2, PtAu, Pt4 and Au4 atoms. Our calculated adsorption energies show that the dopant atoms enhance significantly the binding of the C4H4S and C5H5N molecules. More precisely, the thiophene and the pyridine molecules present a larger interaction with the surface when it is doped with Pt atoms, indicating that Pt atoms have an extremely strong adsorption capacity for both molecules. In addition, the adsorption height of the different configurations shows that the Pt dopant atoms enhance the S-Pt and N-Pt bonds strength, while the C-S and C-N bond distances are elongated in the presence of Pt atoms. The effect of Au atoms is similar to the ones of Pt, albeit the adsorption is weaker. The Bader analysis reveals that charge transfer almost occurs from the thiophene and pyridine molecules to the studied surfaces, with a modest increase in charge transfer in certain cases, while, the charge density difference (CDD) results supported the adsorption behaviour of both molecules. Overall, it is expected that doping the Ag-(100) surface with either Pt or Au atoms will have a significant effect on the reactivity of thiophene and pyridine.