Nucleation and growth of anodic oxide films on bismuth

Abstract

Abstract Combined voltammetry and potentiostatic transient techniques have been used to study nucleation, formation and growth of thin oxide films on high purity polycrystalline bismuth in a borate buffer solution, pH=9.2. It was shown that the initial step in the formation of the continuous anodic layer of bismuth oxide on bismuth is a nucleation process. The potentiostatic technique was a valuable tool in its study. The oxide film nucleation kinetics were explained reasonably well through a 3D progressive nucleation and growth mechanism under diffusion controlled growth. Nucleation potential ( E AN ), steady-state nucleation rate ( AN 0 ) and the number density of growing centres ( N s ) are determined. A detailed mechanistic interpretation of the nucleation process and thickening of the anodic layer under potentiodynamic conditions was obtained using the criteria of cyclic voltammetry.