Electrodeposition of Copper on Platinum (111) Surfaces Pretreated with Iodine: Studies by LEED, Auger Spectroscopy, and Electrochemistry

Abstract

Studies by low energy electron diffraction (LEED) and Auger spectroscopy of copper electrodeposited on well‐characterized platinum (111) surfaces from aqueous sodium perchlorate solutions are reported. Prior to electrodeposition, the platinum (111) surface was pretreated with I2 vapor in ultrahigh vacuum to form a Pt(111) false(√7×√7false) R19.1°‐I superlattice, which protected the platinum surface and the surface of the electrodeposit from attack by the electrolyte and contamination by residual gases. The results were as follows: electrodeposition took place in two narrow, overlapping underpotential deposition linear scan voltammetric peaks followed by one conventional bulk copper deposition peak. Underpotential deposition produced an ordered layer. The first underpotential deposition peak formed a false(3×3false) superlattice in which the unit cell contained four iodine atoms and a comparable number of Cu atoms per nine surface Pt atoms false(θnormalCu=θI=4/9false) . At completion of the underpotential deposition process a false(10×10false) coincidence lattice was present in which θnormalCu=8/9 and θI=4/9 . The iodine Auger signal was not appreciably affected by Cu deposition, indicating that the iodine atoms were present in the topmost layer of the surface at all Cu coverages.

The Underpotential Deposition of Copper on Pt(311): Site Selective Deposition and Anion Effects

“…There have been numerous studies devoted to the phenomenon of underpotential deposition (UPD) of copper on platinum basal single crystal electrodes, especially on Pt(l II) [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16]. In these studies much emphasis has been placed on the effects of halides as well as other adsorbates on the deposition and stripping processes.…”

Electrochemical quartz-crystal microbalance study of silver and copper electrodeposition on bare and iodine-covered platinum electrodes

“…In single-crystal studies, copper deposition onto an iodine-covered platinum surface exhibits very similar electrochemical behavior to that of silver [23,24]. This fact provides an opportunity to study the generality of the effect of an iodine layer on the interactions between metal adatoms and the surrounding electrolyte.…”

“…The charge under peak c1 corresponds to the deposition of the equivalent of 1.6 ML of copper (more than a full upd layer) [23]. However, integration of the entire potential cycle shows an imbalance of 187 lC cm À2 (10% of the cathodic charge), with the anodic charge being less than the cathodic charge.…”

“…On single crystal surfaces, LEED indicates that the CuI structures are well ordered [23], but scanning tunneling microscopy studies performed by Baltruschat et al [27] revealed the formation of three-dimensional islands of copper as the deposition proceeded.…”

The Influence of Iodide Adsorption on Copper Underpotential Deposition on Polycrystalline Palladium Electrodes in Mildly Acidic Solutions

“…In particular, the presence of adsorbable anions on metal UPD at single crystal surfaces has been the subject of many studies (1)(2)(3)(4)(5)(6). Several electrochemical techniques (7)(8)(9)(10), as well as radiotracer (11,12), electron spectroscopy (13,14), optical (15,16) and X ray absorption spectroscopy (17,18) methods, have been employed for the characterization of the UPD process.…”