Quantum Mechanical Investigation of Thiourea Adsorption on Ag(111) Considering Electric Field and Solvent Effects

PATRITO, E. M; COMETTO, F; PAREDES OLIVERA, P

American Chemical Spciety

Año: 2004 vol. 108 p. 15755 - 15755

he adsorption of different thiourea species was investigated on the 111 surface of silver considering electric field and solvent effects with the objective of (a) elucidating the nature of the adsorbed species, mainly in an electrochemical environment, and (b) understanding the energetics and mechanisms of the surface reactions, particularly the oxidative adsorption of thiourea. We first considered the adsorption in vacuum of molecular species such as thiourea (T,U), canonical thiourea, and formamidine disulfide as well as the adsorption of the canonical thiourea radical resulting from the cleavage of the S-H bond. The molecular adsorption of TU in vacuum has the highest binding energy (-33.2 kcal/mol) when the molecular plane is parallel to the surface. However, the strongest surface bond was observed for the canonical thiourea radical (-42.2 kcal/mol) whose nature is the same as that of the methanethiol radical. Externally applied electric fields perpendicular to the surface have an