Online corrosion monitoring of photoelectrochemical cathodic protection of carbon steel using particle video microscope

Abstract

The photo induced open circuit potential and Tafel curves have been widely used to evaluate the photoelectrochemical cathodic protection performance, but these conventional measurements cannot real-time monitor the images of the protected metal, and thus we are not able to judge whether the metal is protected or not during operation. To address these issues, in situ imaging technique based on particle video microscope (PVM) probe is developed to visually monitor the real-time images of the carbon steel. Anatase and rutile TiO2 in different nanostructures were selected as the model photoelectrode materials, and their photogenerated cathodic protection performance was investigated by conventional electrochemical characterizations and in-situ PVM measurements, respectively. The in-situ imaging tool reveals that pitting corrosion can destroy the carbon steel in the chloride containing environment. However, once coupled with the TiO2 photoanodes, the carbon steel can maintain a long-term stability without being corroded. Therefore, the in-situ imaging technique developed in this study provide us a direct route to detect and evaluate the long-term photocathodic protection performance, which will allow us to better clarify the corrosion mechanism, and finally for the better design of photoanode materials.