Potential Dependent Structural Changes of Underpotentially Deposited Copper on an Iodine Treated Platinum Surface Determined In Situ by Surface EXAFS and Its Polarization Dependence
Abstract
An in situ structural investigation of the underpotential deposition of copper on an iodine covered platinum surface (Pt/C layered synthetic microstructure (LSM) with Pt as the outermost layer) has been carried out using surface EXAFS (extended x-ray absorption fine structure) and its polarization dependence. The effects of rinsing the electrode with pure supporting electrolyte have also been investigated. At an applied potential of +0.20 V (corresponding to half a monolayer of electrodeposited copper) there are two in- plane Cu-Cu distances: 2.56+/-0.05A and 4.21+/-0.05A. This suggests a coexistence between a close-packed phase with a more open phase. It is likely that the open phase is stabilized by repulsive interactions between partially charged copper atoms, as well as by the presence of the strongly adsorbed iodine layer. At +0.10V (corresponding to a full monolayer of electrodeposited copper) there is only one Cu-Cu distance of 2.56+/-0.05A. Combining in-plane (delta polarization) and monolayer coverage, the copper UPD layer is incommensurate with respect to the platinum surface. The iodine ad-layer rides the electrodeposited copper forming a 3x3 unit cell. This interfacial structure is not altered upon rinsing with pure supporting electrolyte.
Document Details
- Document Type
- Technical Report
- Publication Date
- Aug 25, 1993
- Accession Number
- ADA269890
Entities
People
- D. Acevedo
- G. M. Bommarito
- Héctor D. Abruña
- J. F. Rodriguez
Organizations
- Cornell University Department of Chemistry and Chemical Biology