Effects Of Anodizing Parameters And Titanium Substrate Structure On Growth Behavior Of TiO₂ Nanotubes

One-dimensional ordered TiO₂ nanotube arrays(TNTs)have broad application prospects in energy storage devices,sensors,solar cells,photocatalysis and other fields,are of large specific surface areas,high mechanical strength,strong adsorption capacity,and unique optical and electrical characteristics.It is one of the hot spots in the field of energy materials that how to stably prepare TNTs with controllable structure and performance.Nanotube length,diameter,tube wall thickness,tube spacing,and other micro-morphology have an important impact on its performance.Nevertheless,in the process of improving the microscopic morphology of TNTs by adjusting the anodizing parameters,it is often encountered that the prepared TNTs have large cracks and even directly peeled off from the Ti substrate,resulting in the problem that TNTs-based devices cannot be successfully prepared.It is of great significance to prepare TNTs with high order,controlled microscopic morphology and tight bonding with the substrate by systematically studying the effects of temperature,time,voltage and other anodizing parameters and the microstructure of the Ti substrate on the growth behavior of TNTs.In this study,anodic oxidation method was applied to prepare TiO₂nanotube arrays in an organic electrolyte composed of water,NH4F and ethylene glycol.The anode growth rule of TiO₂ nanotube arrays within the temperature range of 30??60?and the voltage range of 30V?50V was studied.Kinetic analysis shows that the main mechanism for controlling the growth of TiO₂ nanotubes is"field-induced dissolution".The linear relationship between the growth rate of the length and diameter of the nanotubes and temperature follows the Arrhenius relationship.The activation energy of increasing length of TiO₂ nanotubes is much larger than that of increasing diameter,and is a linear decreasing function of anodizing voltage.The experimental results reveal that there is a power-law relationship between the growth rate of the nanotube length and the anodizing voltage,which can be used to describe the growth of TiO₂ nanotubes under steady state.Secondly,this study discovered that the morphology and other characteristics of TiO₂ nanotubes have a great relationship with the crystal orientation and microstructure of the underlying Ti metal substrate.In this study,the microstructure and roughness of the titanium matrix were discussed by electron backscatter analysis(EBSD)combined with atomic force microscopy(AFM)and X-ray diffraction analysis(XRD),and the morphology was characterized by scanning electron microscopy(SEM).The experimental results show that:on a titanium substrate with a(0001)surface texture,the growth rate of TiO₂ nanotubes grows faster as the roughness decreases;for the same titanium plate,as the corrosion depth increases,the TiO₂ nanotube film on the surface and the titanium substrate have a greater binding force;as the thickness decreases,the dislocation density of titanium plates with different thicknesses gradually increases,and the bonding force gradually decreases.In addition,the fast spatial Fourier transform diffraction pattern of the SEM image of the TiO₂ nanotube array shows that the narrow TiO₂ nanotubes have a uniform diameter,wall thickness and arrangement.