Electrodeposition of Sb onto the low-index planes of Cu in aqueous chloride solutions: studies by LEED, AES and electrochemistry

The underpotential deposition (UPD) of Sb on Cu(111), Cu(100) and Cu(110) h as been studied using ultra-high vacuum electrochemistry (UHV-EC) technique s. Sb was deposited from acidic chloride solutions and analyzed with Auger electron spectroscopy, low-energy electron diffraction and cyclic voltammet ry. A feature observed only in the first voltammetric cycle, starting from the rest potential, appears to be Sb UPD on the copper surfaces. Prior to S b UPD, Cl structures were observed on each of the three Cu planes. When the potential was scanned into the transient reductive feature, antimony began to deposit, displacing the chlorine. Initially, structures containing both Cl and Sb were formed on the Cu surfaces, including a (root3 x root3)R30 d egrees on the Cu(111), a (2 root2 x root2)R45 degrees on the Cu(100), and a structure denoted in matrix notation as ((1)(-1) (3)(1)) formed on Cu(110) . Further Sb deposition results in displacement of the chloride and new str uctures on each face: Cu(111)(3 x root 21)-Sb, Cu(110)(3 x 2) and Cu(100)(3 x 2). Scanning the deposition potential further negative, into bulk Sb dep osition, yielded no well-ordered structures.