The Photoelectric Chemical Corrosion Protection Of W Modified TiO₂ Thin Films

TiO₂ has many advantages,such as non-toxic,harmless,stable performance and so on.Since the Japanese scientist Tsujikawa TiO₂ has found the photocathodic protection role on the surface of stainless steel,more directly into the TiO₂ as the photocathodic protection door.Photocathode protection has the advantage of not sacrificing supplies.However,the photoelectric conversion efficiency of TiO₂ and TiO₂ in low light conditions can not continue without the metal photocathodic protection,and application of TiO₂ photocathode protection is narrow,mainly used in carbon steel,copper and stainless steel,widely used because of limitations of TiO₂ is low the Fermi level of TiO₂.The theoretical calculation of W doped TiO₂ can improve the Fermi level of TiO₂,but it is not verified from the experimental point of view.In this paper,the effect of W doping on the Fermi level of TiO₂ is studied.Study on the photoelectrochemical response of WO₃/TiO₂ laminated,mixed WO₃-TiO₂ and W-TiO₂ coatings on pure titanium surface firstly,and then the influence of the first principle of the W doped TiO₂ Fermi level is calculated,the photoelectrochemical W-TiO₂ ring coating on the surface of magnesium alloy should be at the end of.The main results are as follows:?1?Through the optimization of the electro chemical reaction of WO₃/TiO₂,WO₃-TiO₂ and W-TiO₂ coatings on the surface of pure titanium,the optimum parameters were obtained:1)WO₃/TiO₂ stack: the number of layers of WO₃ film is 9 layers,the layer number of TiO₂ film is layer of,the concentration of WO₃ sol is 7at%,and the heat treatment temperature of WO₃ is about 500?.2)WO₃-TiO₂ mixed coating: WO₃:TiO₂ is 1at%,the heat treatment temperature is 400 ?,the film thickness is,the concentration of TiO₂ is about 1.5wt%.3)W-TiO₂ coating: W doping amount of 7at%,heat treatment temperature of 300 ?,TiO₂ concentration of 1.5wt%,film thickness of 9 layers.?2?The W doped TiO₂ and the relationship between W-TiO₂ and heat treatment temperature were fitted by Mott-Schottky curve.1)?7at%?W doped TiO₂ can improve the Fermi level of TiO₂,and the Fermi level increases with the doping amount of W.Through the first principles simulation,it is found that the reason for the increase of the TiO₂ Fermi level by W doping is that the 5d orbitals of the W and the Ti of the 3d are hybridized,so that the Fermi level of the TiO₂ is increased to the conduction band,thus increasing the Fermi level of TiO₂.2)when the heat treatment temperature is about 400 ?,the Fermi level of W-TiO₂ is the highest.When the heat treatment temperature is higher than 400 ?,a large number of Na₂WO₄ appear in the crystal,which leads to the decrease of the Fermi level of W-TiO₂.?3?Optimization of the electro chemical reaction of WO₃/TiO₂,WO₃-TiO₂ and W-TiO₂ coatings on the surface of pure magnesium was carried out:1)WO₃/TiO₂ stack: WO₃ thickness of 3 layers,TiO₂ thickness of the layer of,the concentration of WO₃ is 1at%,the concentration of TiO₂ is about 1wt%,and the heat treatment temperature is about 300?.2)WO₃-TiO₂ mixed coating: WO₃:TiO₂ is 3at%,the heat treatment temperature is 400 ?,the film thickness is,the concentration of TiO₂ is about 0.5%.3)the doping concentration of W is 5at%,the heat treatment temperature is 500 ?,the film layer is,and the concentration of TiO₂ sol is about 1wt%.