INVESTIGADORES
OVIEDO Oscar Alejandro
artículos
Título:
A New Approach for the Calculation on the Entropic and Free Energy Contributions to Underpotential Deposition
Autor/es:
L. M. FARIGLIANO, M. A. VILLARREAL, O. A. OVIEDO AND E. P. M. LEIVA
Revista:
The Electrochemical Society Transaction
Editorial:
The Electrochemical Society
Referencias:
Año: 2014
ISSN:
1938-5862
Resumen:
In the present work we have studied the electrochemical nonpseudomorphic formation of Pb
bidimensional structures on Au(111) surfaces. Based on the two-phase thermodynamic method, we have
analyzed, from a computational perspective, entropic and energetic contributions to underpotential
deposition. The occurrence of incommensurate nanophase formation, rotation of the adsorbate with
respect to the substrate, and the effect of expansion and compression of the Pb monolayer were also
analyzed. Our results show that the entropic contribution to monolayer underpotential deposition of Pb on
Au(111) at room temperature is approximately 20% of the total free energy excess. For very small
clusters, this contribution increases up to 45%. Simulations show that in the early stages of formation, Pb
nanophases grow without rotation. When the size of the Pb islands is close 100 atoms, a rotation process
takes places. At relatively high coverage, a strong lateral compression of Pb monolayer sets on, evidenced
by a sharp decrease in the distance between nearest neighbors.