Studies On The Synthesis And Photocatalytic Activity Of Through-hole TiO₂ Nanotube Arrays

In recent years,TiO₂ is widely used in the field of waste water degradation and solar cell,etc,because of its advantages of good photocatalytic activity,wide band gap,photochemical stability,non-toxic and wide source,etc.Compared to other types of TiO₂nano materials,TiO₂ nanotube array materials have higher specific surface area,better adsorption performance,better stability and more excellent performance.However,the structure of traditional TiO₂nanotube array materials is one side open.While through-hole TiO₂nanotube arrays（Th-TNTAs）can break through the structure defects of traditional materials,improve the photoelectric conversion efficiency,reduce materialof the electron hole pair recombination rate and broaden the scope of its application.Currently,anodic oxidation method is commonly used for the preparation of TiO₂ nanotube arrays.As for through-hole TiO₂ nanotube arrays,the common preparation method are the atomic layer deposition,high voltage breakdown,physical separation,all those methods are based on the anodic oxidation method,then open end by those ways.This paper for the first time prepared Th-TNTAs by bilayer Ti oxidation method,based on the anodic oxidation method.Through the analysis of the structure and the surface morphology of Th-TNTAs by SEM,TEM and other means,the paper discusses the influence of the experimental conditions on the Th-TNTAs surface morphology,such as voltage.In addition,we have studied the bottom opening effect on its photocatalytic activity in the application of photodegradation of methylene blue and CO₂ photoreduction.Finally,we establish the TiO₂nanotube growth model propared by anodic oxidation method,from the research of effect on the principle and process conditions in the anodic oxidation.The main conclusions are as follows:1)Bilayer oxidation method can prepare the T-h TiO₂ nanotube arrays.2)With the increase of temperature,the nanotube diameter increases first and then decreases.The surface morphology of Th-TNTAs in 70℃is the best.Under the same temperature,oxidation time decreases with the increase of voltage.the oxidation time changes little at lower or higher temperature,while at 30-45℃it changes quickly.Under the same voltage,oxidation time decreases rapidly with the increase of temperature.With the increasing of the voltage,the diameter first increases and then decreases in the low temperature region.3)Compared to TNTAs,the catalytic activity of Th-TNTAs is improved greatly,and the efficiency increases by 8 times.The efficiency of 121μm length catalyst is further improved than the 53μm catalyst with the degradation of MB at the same time.4)The anodic oxidation voltage is the main driving force in the nanotube growth progress.The main factor influencing the growth of nanotubes is the voltage on the oxidation layer,pressure,electrolyte temperature,concentration and the properties of TiO₂ itself.