Photogenerated Cathodic Protection Properties of Nanoa2sized TiO2/ Sb2O5 Coating

Nano-sized TiO2/Sb2O5 bilayer coatings were prepared on type 304 stainless steel substrate by sola2gel method. Surface morphology, structure and composition of the asa2prepared TiO2/Sb2O5 coatings were characterized by scanning electron microscope (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscope (XPS). The performance of photoa2electrochemical and photogenerated cathodic protection of the coatings was investigated using the electrochemical method. SEM results indicate that the coating surface is continuous, uniform and dense, XRD results show that the coating is of anatase TiO2, XPS results indicate the outer and inner coatings are mainly composed of Ti, Sb, C and O elements. Moreover, the test results of the steady potential and polarization curves demonstrate that the nanoa2sized TiO2/Sb2O5 bilayer coating has worsen photoa2electrochemical properties than the plain nanoa2sized TiO2 coating in 3% NaCl solution. Type 304 stainless steel coated with the bilayer coating can maintain cathodic protection for 4h in the dark after irradiation by UV illumination for 1h. In addition, a novel mechanism of the photogenerated cathodic protection for the bilayer coating is put forward.