Long-Term Photoelectrochemical Cathodic Protection by Co(OH) 2 -Modified TiO 2 on 304 Stainless Steel in Marine Environment

Abstract

© The Author(s) 2018. The long-term photoelectrochemical cathodic protection by Co(OH)2-surface modified TiO2of anatase nanotubes and rutile type, prepared by anodic oxidation has been studied in aqueous 3.5 wt% NaCl solution. Electrochemical measurements have been used to evaluate the photoelectrochemical protective properties of both Co(OH)2-modified TiO2coupled with 304 stainless steel in 3.5 wt% NaCl solution under illumination and in the dark. Morphologies, crystal structures, surface compositions, and light response range of both Co(OH)2-surface modified TiO2films before and after immersion were characterized, respectively, by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), UV-Vis spectrophotometry. The results show that the photogenerated electrode potential of both types of TiO2films modified with Co(OH)2is more negative affording protection of 304 stainless steel than that of the non-modified TiO2under illumination. These TiO2films provide a long period (12 h) of protection. The anatase-TiO2nanotube film always shows a better protection performance than rutile-TiO2film.