Morphology Of TiO2 Nanotube Arrays Research Articles

Recent Progress in Anodic Oxidation of TiO2 Nanotubes and Enhanced Photocatalytic Performance: A Short Review

By adjusting the oxidation voltage, electrolyte, anodizing time and other parameters, TiO2 nanotubes with high aspect ratio can be prepared by oxidation in organic system because anodic oxidation method has the advantage of simple preparation process, low material cost and controllable morphology. This review focusses on the influence of anodizing parameters on the morphology of TiO2 nanotube arrays prepared by anodizing. In order to improve the photocatalytic activity of TiO2 nanotubes under visible light and to prolong the life of photo-generated carriers, the research status of improving the photocatalytic activity of TiO2 nanotubes in recent years is reviewed. This review focusses on the preparation and modification of TiO2 nanotubes by anodic oxidation, which is helpful to understand the best structure of TiO2 nanotubes and the appropriate modification methods, thus guiding the application of TiO2 nanotubes in practical photocatalysis. Finally, the development of TiO2 nanotubes is prospected.

The effect of first step anodization time on morphology and photocurrent response of TiO2 nanotube arrays for application in backside illuminated dye-sensitized solar cells

We report on the effect of the first step anodization time on the morphology of TiO2 nanotube arrays grown by the two-step anodization and their photocurrent response in the backside-illuminated dye-sensitized solar cells. Results show a remarkable increase of tube ordering by increasing the first step anodization time. The Fill factor and open circuit voltage of all dye-sensitized solar cells were approximately 60% and 0.77V respectively, for a range of first step anodic oxidation from 0.5 to 6h, whereas the short circuit current increased from 0.94 to 1.57mA/cm2 leading to an enhanced photo-to-current efficiency by 73%. According to open circuit voltage decay and electrochemical impedance spectroscopy (the Nyquist and Bode plots), we attributed such an enhanced cell performance to lower recombination rates due to higher ordered TNAs associated with the actual surface area and coherency of the cells' components.

Simulation of anodizing current-time curves and morphology evolution of TiO2 nanotube arrays

Through introducing appropriate additives into the electrolytes, the morphology and growth efficiency of TiO2 nanotube arrays (TNTAs) have been greatly influenced. The anodizing current transients and the corresponding morphology of TNTAs were investigated and compared in detail by SEM. To further understand the mechanism, the measured current-time curves obtained during the anodization of titanium in the electrolytes with different additives are simulated. Notably, in the total anodizing current, the ionic current is separated from the electronic current according to the present model, and that the electronic current and ionic current make different contributions to the growth of TNTAs. It is found that the initiation of nanopores may be caused by the rupture of the oxygen bubbles occluded in the growing oxide, and the opening of nanotubes is thought to be close related to the disturbance effect of the rising bubbles (caused by electronic current). The present results would be helpful for understanding the formation mechanism of TNTAs from the perspective of ionic and electronic current. And practically, the nanotube length can be predicted and deduced quantitatively via simulating and comparing electronic and ionic current.

Controllable preparation, growth mechanism and the properties research of TiO2 nanotube arrays

In this paper we prepared titanium nanotube arrays in ethylene glycol organic electrolyte which contains ammonium fluoride through anodic oxidation method. We found that the preparation of the structure and morphology of TiO2 nanotube arrays can be controlled by changing the preparation parameters. While the oxidation voltage is the main factor that controls the diameter of nanotubes, the length of nanotubes is mainly depending on the oxidation time, and the crystal type is closely related to the annealing temperature. Its photo-degradation rate of methylene blue can reach to 92% which is almost two times than the titania(P25).

Fabrication of TiO<sub>2</sub> Nanotube Arrays in Ethylene Glycol Electrolyte by the Electrochemical Anodization Method

Highly-ordered TiO2 nanotube arrays were successfully fabricated by electrochemical anodization of titanium. The morphology of TiO2 nanotube arrays, the length and pore size were represented by field emission scanning electron microscopy (FE-SEM). The parameters of various anodization including F- concentration, reaction temperature and anodization voltage were investigated in detail. The results show that as-prepared TiO2 nanotube arrays possess good uniformity and well-aligned morphology in mixture of ethylene glycol and 0.3 wt% NH4F electrolyte at 40 V for 25 °C. The growth rates of TiO2 nanotube arrays can show activation energy.

Fabrication of TiO<sub>2</sub> Nanotubes Array by Anodization for DSSC

TiO2 nanotubes array was fabricated by anodization. Effect of reaction duration on the morphology of TiO2 nanotube arrays was studied detailedly. The structure and morphology of the prepared nanotubes array was characterized by X-ray diffraction and scanning electron microscopy, respectively. The fabricated TiO2 arrays were peeled off and adhered to FTO glass with adhesive (mixture of tetrabutyl titanate and polyethylene glycol), then they were sintered at 450 for photoanode of DSSC. The photovoltaic performance of the prepared sample as the DSSC anode was investigated. An open circuit voltage of 0.69V and a short circuit current density of 7.78mA/cm2 were obtained, and the fill factor and the convert efficiency were 0.517 and 2.78%, respectively.

TiN Nanotube Arrays as Electrocatalytic Electrode for Solar Storable Rechargeable Battery

TiN nanotube arrays on the metallic Ti mesh, prepared by a simple nitridation of TiO2 nanotube arrays on the metallic Ti mesh in ammonia atmosphere, are introduced for the first time as low-cost electrocatalytic electrode for solar storable rechargeable battery. The microstructure of the as-prepared TiN nanotube arrays/Ti mesh is characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). It is shown that the obtained TiN retains its parent morphology of TiO2 nanotube arrays after the calcination in ammonia atmosphere. It is demonstrated from cyclic voltammetry (CV) and electrochemical impedance spectra (EIS) that the highly ordered TiN nanotube arrays on the metallic Ti mesh substrate show an excellent electrocatalytic activity. Correspondingly, the rechargeable battery with WO3/carbon nanotubes as charge-storage electrode and TiN nanotube arrays/Ti mesh as electrocatalytic electrode presents reliable solar storable capability and reversible electrochemical conversion performance. Therefore, the TiN nanotube arrays/Ti mesh prepared in this work can be used as a potential low-cost alternative to the expensive noble metal Pt in future applications of the solar storable rechargeable battery.

Modified TiO2 nanotube arrays (TNTAs): progressive strategies towards visible light responsive photoanode, a review

Since first introduced by Zwilling and co-workers in 1999, titania nanotube arrays (TNTAs) fabricated by simple electrochemical anodization method have attracted great interest due to their outstanding photoelectrochemical properties which render them the most promising candidate for many solar energy harvesting applications. In this contribution, the fabrication, properties, and applications of TiO2 nanotube arrays have been reviewed, with special focus on synthesis by anodization in fluoride-containing electrolytes. The effect of anodization process parameters such as electric potential, pH, anodization duration and electrolyte composition on the size, and morphology of TNTAs has been discussed in detail. Electronic property modification strategies of the wide band gap TNTAs to enhance the material responsiveness to visible light irradiation have also been reviewed. Modification strategies include nonmetal doping such as nitrogen, carbon, boron and sulfur; metal ion doping such as Fe, Zn, Zr and Cr; surface decoration with precious metal nanoparticles such as Pt, Ag, Au; and sensitization with CdS nanoparticles.

Effects of Anodic Titanium Oxide Nanotube Arrays on Dye‐Sensitized Solar Cells

AbstractThis work has utilized the anodic oxidation method to fabricate the TiO2 nanotube arrays which were then applied as the anode to the dye‐sensitized solar cells (DSSCs). Surface morphology of TiO2 nanotube arrays, the length and the pore diameter of the nanotubes were observed by FE‐SEM. With XRD analysis, the annealed TiO2 nanotube array has been identified as the anatase phase which can enhance the electron transition in the TiO2. The influence of the TiO2 nanotube arrays to the absorption of the dye molecules was examined by UV‐VIS spectroscopy. It is found that the TiO2 nanotubes with longer lengths can improve the dye absorption, thus increases the photovoltaic conversion efficiency of the DSSCs. The DSSCs with TiO2 nanotube arrays have achieved photovoltaic conversion efficiency as high as 4.62% in this work.

Synthesis of TiO<sub>2</sub> Nanotube Arrays Through Multistep Anodization

Multistep electrochemical anodization is an electrochemical experiment orderly conducting in different electrolytes. In this paper, TiO2 nanotube arrays have been firstly anodic grown in aqueous electrolyte (H3PO4/HF) and later anodic grown in organic electrolyte (glycerol/NH4F). Compared with separately anodizing in aqueous and organic electrolyte, the morphology of the resulting nanotube arrays can be optimized. SEM images showed that the obtained nanotubes have a length of more than 2 μm and single-pore diameter ranging from 120 to 150 nm. The current work indicates that the multistep electrochemical anodization has a contribution to the optimization of the morphology of TiO2 nanotube arrays.