Titanium Dioxide Nanomaterial Modified With Metal Selenide For Photocathodic Protection Of 304 Stainless Steel

TiO₂ nanometer film shows attractive prospects in the field of metal corrosion protection,because it owns good photoelectric property,photocatalytic performance,environmental friendliness and chemical stability,attracts extensive attention.However,TiO₂ as a wide bandgap semiconductor can only effectively response to ultraviolet light?only accounts for 5% of the solar spectrum?so that its solar energy utilization is extremely low.Moreover,the recombination rate of photogenerated electron-hole pairs in TiO₂ is high and the photoelectric conversion efficiency is low,which limits its photogenerated cathodic protection performance for 304 stainless steel?304SS?.Lots of research has been carried out to solve these problems.The main goal and motivation of this dissertation is to explore the photogenerated cathodic protection performance and mechanism of titanium dioxide nanomaterial modified with metal selenide for 304 SS.The arranged orderly TiO₂ nanotube arrays film was prepared on the surface of titanium substrate via anodic oxidation.Then NiSe₂ and WSe₂ metal selenide semiconductor nanomaterials were modified on the TiO₂ nanotube arrays film through electrochemical deposition,respectively.The surface morphology,phase structure and optical response performance of prepared samples were characterized by scanning electron microscope?SEM?,X-ray diffraction?XRD?and UV-Vis diffuse reflection spectroscopy?UV-Vis DRS?.The photogenerated cathodic protection properties of TiO₂ nanotube arrays film and modified nanocomposite films for 304 SS were tested by a combined technology of the corrosion electrochemistry testing technology and photoelectric technology in 3.5 wt.% NaCl solution.?1?Different amount of NiSe₂ nanoparticles were modified on the surface of TiO₂ nanotube arrays film via changing the cycle number of electrochemical deposition.The NiSe₂/TiO₂ nanocomposite with the optimal photogenerated cathodic protection performance for 304 SS was selected.It turns out that the existence of NiSe₂ nanoparticles promoted visible light response of TiO₂ nanotube arrays film,enhanced its photogenerated cathodic protection property for 304 SS.NiSe₂/TiO₂ nanocomposite owned the optimal photogenerated cathodic protection for 304 SS while the cycle number of electrochemical deposition was 2.The photogenerated current density and open circuit potential of 304 SS coupled with this nanofilm were 283 ?A/cm2 and-730 mV,respectively.?2?Different WSe₂/TiO₂ nanocomposite films was prepared through changing the additive amount of SeO₂ in electrolyte.The effects of SeO₂ content on the visible light response and photogenerated cathodic protection properties of as-prepared WSe₂/TiO₂ nanocomposite films were investigated.The results showed that the visible light response and photogenerated cathodic protection properties of WSe₂/TiO₂ nanocomposites were better than pure TiO₂ nanotube arrays film.WSe₂/TiO₂ nanocomposite film prepared in the electrolyte with 20 mg SeO₂ exhibited the optimal photogenerated cathodic protection performance for 304 SS.The photogenerated current density of 304 SS coupling with this composite under visible light irradiation can reach 206 ?A/cm2,and the open circuit potential negatively shifted to-800 mV.