Anodic dissolution of cobalt in aqueous sodium nitrate solution at high current densities

The present work focuses on the anodic dissolution of cobalt and the surface texture development in 2.9 mol/L sodium nitrate solution under current controlled conditions at 25 and 30 A/cm2. Before the electrochemical experiments the crystallographic orientation of the samples was investigated by EBSD. The anodic behavior of cobalt as well as the surface topography was microscopically observed using a special electrochemical through flow cell in-operando during the current controlled dissolution. The experiments were completed by SEM/EDX-analysis. The authors evidence that the dissolution process at high current densities is independent of the crystallographic orientation of the sample and leads to a surface polishing. The current efficiency is approximately 100%. Only a weak and temporary oxygen evolution was detected at 25 A/cm2.