Effect Of Electrolyte Pretreatment On Formation Of Anodic TiO₂ Nanotubes

TiO₂ nanotube arrays obtained by electrochemical anodization are widely used because of their highly order and high specific surface area.The growth of nanotubes is controlled by solution diffusion during the process of preparation of TiO₂ nanotubes by electrochemical reaction.In order to study the effect of diffusion on the growth of nanotubes,a large number of experiments enhanced the diffusion of the solution by agitation and sonication during anodic oxidation.In order to study the effect of diffusion on the growth of nanotubes,the application of ultrasound agitation and magnetic stirring during the preparation of TiO₂ nanotube arrays may change the diffusion process in electrolyte in many experiments.However,there is no report on the effect of solution pretreatment on the growth of nanotubes.In this paper,we mainly study the effect of different solution pretreatments on the growth of titanium oxide nanotubes.The anodic oxidation reaction was carried out in an ethylene glycol solution containing 0.3 wt.% NH4 F and 2 vol.% Deionized water.Pretreatment of the electrolyte before anodic oxidation:?1?statically leaving for 24 h,?2?magnetic stirring at 500 rpm for 30 min first and leaving for 24 h or?3?used immediately after the stirring,?4?ultrasonic agitating for 30 min first and then leaving for 24 h or?5?used immediately after the ultrasonic agitation.On this basis,the effect of sealed treatment were studied.The experimental results showed that magnetic stirring and ultrasonic agitating facilitate the diffusion of ionic species and were beneficial to the growth rate of the nanotubes;at the same time,the growth of nanotubes in the sealed is larger than the unsealed under the same pretreatment conditions.During the pretreatment of the solution,two processes of material incorporation and evaporation were considered.In this paper,nitrogen or oxygen was bubbled into the solution and then subjected to anodic oxidation experiments to verify the effect of the incorporation of the material.The effect of pretreatment duration and water content on the growth of nanotubes was studied to verify the material evolution process.The experimental results showed that the addition of nitrogen and oxygen does not significantly inhibit the growth of nanotubes.The contact in the unsealed solution is more likely to escape relative to the seal,due to the difference in contact of the solution with the environment due to sealing and non-sealing.The main reason for the growth rate difference between the sealed and the unsealed solution is the evaporation of water from the solution.In this paper,the effects of magnetic stirring and ultrasonic treatment on the growth of nanotubes were systematically studied,and the effects of solution sealed and unsealed on the growth of nanotubes were analyzed in detail.The experimental results showed that magnetic stirring is best way for solution pretreatment before anodic oxidation.We do the related research for the electrochemical anodic oxidation solution to establish a standard,and to avoid the differences caused by the details brought out the misjudgmed experimental results.