Characterization of passive films on tin through transient electrochemical techniques

Abstract Voltammetry and chronoamperometry were employed to derive mechanistic information about the electroreduction of anodic films on tin. This information proved useful to gain a deeper insight into the complex passivation process as well as into the passive layer changes generated by the anodizing procedure. Tin electrodes were anodized in carbonate–bicarbonate buffers covering a wide range of pH and electrolyte composition. Two cathodic peaks were detected in the voltammetric response and they were correlated with two maxima present in electroreduction current transients. The second electroreduction process corresponds to a surface species generated during the anodic potential bias at the beginning of the secondary passivity range. This process has distinct features and is dependent on anodizing time, solution agitation and ionic strength of the electrolyte.