New insights on the Sn underpotential deposition on Au(100)

L.A. MEIER; S.G. GARCÍA; D.R. SALINAS

SURFACE AND INTERFACE ANALYSIS

JOHN WILEY & SONS LTD

Año: 2012 vol. 44 p. 37 - 40

0142-2421

The underpotential deposition (UPD) of Sn in the system Au(100)/Sn2+, SO42- has been studied by classical electrochemical techniques and in situ scanning tunneling microscopy (STM). The results show that the Sn UPD initiates at relatively high potentials with the formation of a quasi-hexagonal structure characterized as Au(100)-(√2x7)R45º. This expanded overlayer contributes to the modification of the surface morphology which exhibits flat terraces with step edges showing angles of 60º or 120º. At lower potentials twodimensional islands are formed which tend to grow causing a coverage increase. In the underpotential region close to the formation of the 3D bulk phase the long time polarization experiments indicate the formation of different Au-Sn alloy phases.