The Fe-doped TiO2 nanotube arrays as a photoanode for cathodic protection of stainless steel

Abstract

A highly ordered Fe-doped TiO2 nanotube layer was fabricated by potentiostatic anodization of pure titanium in fluorinated electrolyte solutions containing iron ions. The structure and composition of the as-prepared TiO2 nanotubes were characterized by SEM, XRD, UV-Vis, and YCPS. The effects of temperature, time, dopant content on the morphologies, structure and photochemical properties of the TiO2 nanotube arrays were investigated systemically. The performances of photogenerated cathodic protection and the photoelectrochemical response for the Fe-doped TiO2 nanotube layers under illumination and dark conditions were evaluated through the electrochemical measurements. It was found that Fe ions in the TiO2 nanotube arrays could suppress the recombination of photogenerated hole-electron. The Fe-doped TiO2 nanotubes showed a stronger absorption in the 410-650 nm range. The open-circuit potentials of 316L SS (stainless steel) coupled with the Fe-doped TiO2 nanotubes layers shifted negatively under visible light irradiation (lambda >400 nm), and maintained negatively for a period even in dark condition. It was indicated that the Fe-doped TiO2 nanotubes layers were able to create effectively a photogenerated cathodic protection for metals under regular sunlight conditions.