The influence of halide ions at submonolayer levels on the formation of oxide layer and electrodissolution of copper in neutral solution

C. I. ELSNER; R.C. SALVAREZZA; A.J. ARVIA

ELECTROCHIMICA ACTA

PERGAMON-ELSEVIER SCIENCE LTD

Lugar: Amsterdam; Año: 1988 vol. 33 p. 1735 - 1741

0013-4686

The formation of submonolayers of copper (I) halide preceding anodic oxide layer growth and copper electrodissolution has a remarkable influence on these two processes. Chloride electroadsorption on copper al the submonolayer level takes place as two successive stages at potentials 0.7V lower than the reversible potential of the Cu/CuCl redox couple. Similar results are obtained for iodide, bromide and fluoride ions although the driving force for electroadsorption decreases in the order I->Br->Cl->F-. The relative contribution of OH- and halide ion electrodeposition can be modified through the solution composition, applied potential and eleadsorption time. The increase surface coverage by the electroadsorbate diminishes the amount of the passive oxide layer and strongly increases the metal electrodissolution rate, particularly when the amount of passive oxide layer becomes smaller than that required to form a compact monolayer.