The Hydrophilicity And Photoelectric Properties Of TiO₂ Nanotube Arrays

Self cleaning materials are used in many areas in life,such as decorative materials,window glass,auto mirror and solar panels,etc.Among all the self-cleaning materials,TiO₂ has been widely concerned owing to its excellent chemical stability,non-toxic,non-pollution,rich in resources,low price and so on.However,there are still some problems,such as the hydrophilic mechanism of TiO₂ film is not clear,the relationship between the photocatalytic properties with hydrophilicity is still in the research stage.Most of the TiO₂ films have super hydrophilicity after light treatment,which can not be used on the condition of insufficient illumination or rainy days.Therefore,in this paper,a kind of TiO₂ self-cleaning film with super-hydrophilicity without light has been prepared,surface modified and doped,aiming to improve the self-cleaning performance of TiO₂ nanotube arrays?TiO₂-NTAs?.?1?The TiO₂-NTAs with a diameter about 110 nm were prepared by electrochemical anodic oxidation using titanium plate as anode,platinum as cathode,H3PO4 and?CH2OH?2 added NH4 F as the electrolyte,respectively.The initial value of the water contact angle of the TiO₂ nanotube arrays prepared with?CH2OH?2 is 14.5°,which is much lower than that of the contact angle?133.67°?of the TiO₂-NTAs prepared under the same conditions in the H3PO4 electrolyte,and the hydrophilic mechanism of TiO₂-NTAs is also investigated.?2?The TiO₂-NTAs were successfully prepared being annealed with aluminum powder by the chemical reduction.The results show that with the increase of annealing temperature,the water contact angle of TiO₂-NTAs shows a trend of increasing and then decreasing.The water contact angle of the TiO₂-NTAs annealed at 300? and 450? reduces obviously after the illumination.In addition,the absorption range of the black TiO₂-NTAs obtained after annealing at 300? and 450? extends from ultraviolet light to visible light,greatly improving the utilization of visible light.?3?N,S-codoped black TiO₂-NTAs were successfully prepared using?NH4?2SO4 as N source and S source by nonmetal ion doping.The results show that the water contact angle of TiO₂-NTAs decreases with the increase of N and S content.When the additive amount of?NH4?2SO4 is 0.5 g,the contact angle decrease to 10°,and then decrease to 7.5° after illumination.Moreover,the N,S-codoped TiO₂-NTAs have obvious absorption to visible light,and their optical absorption properties become stronger with the addition of?NH4?2SO4.