Simulación de Monte Carlo Continuo de Depósitos de Baja Dimensionalidaa

O. A. OVIEDO, M. I. ROJAS, E. P. M. LEIVA

Córdoba, Argentina

Jornada; 2da Jornadas de Postgrado de la Fac. de Ciencias Químicas; 2007

Facultad de Ciencias Químicas, Escuela de post-grado

Off lattice Monte Carlo simulations of low dimensional

deposit on Pt(111)

O.A. Oviedo, M.I. Rojas, E.P.M. Leiva

In the present work, the deposition of Ag, Cu and Pd on real Pt(111) surfaces was studied by

means of off lattice Monte Carlo simulations (MC) with embedded atom method potentials (EAM) in the canonical ensemble (NVT) at 300K. The deposit can be classified by its lattice periodicity and considered as a low dimensional structure. The structural and energetic properties of low dimensional surface defects (iD, 0£i£2) was also considered, such as vacancy (0D); kink (0D) and steps (1D). The adsorption of Ag, Cu and Pd on a Pt(111) surface with defects was studied at low coverages. For single atom adsorption, the adsorption energy increases with the dimensionality of the surface defect:

 

U_Vacan(0D)< U_Kink(0D)< U_Step(1D)< U_Terrace(2D)

 

When coverage increases, the decoration of monoatomic steps is completed first, then starting the coverage on the terraces. From the analysis of the adsorption energies per atom, it is observed that this increases with the increase of the dimensionality:

 

U_Step (1D)< U_Terrace (2D)< U_Bulk(3D)

 

This is in agreement with the sequence of adsorption peaks observed in the cyclic voltammogram [1].

 

 

[1] W. J. Lorenz, G. Staikov, W. Schindler and Wiesbeck, J. Electrochemical Soc. 149 (12) K47-

K59 (2002).