scholarly journals Rutile phase n- and p-type anodic titania nanotube arrays with square-shaped pore morphologies

2015 ◽  
Vol 51 (37) ◽  
pp. 7816-7819 ◽  
Author(s):  
Piyush Kar ◽  
Yun Zhang ◽  
Samira Farsinezhad ◽  
Arash Mohammadpour ◽  
Benjamin D. Wiltshire ◽  
...  
Keyword(s):  
Elevated Temperature ◽  
Anatase Phase ◽  
Rutile Phase ◽  
Nanotube Arrays ◽  
Morphological Transformation ◽  
Furnace Annealing ◽  
Photoelectrochemical Activity ◽  
Titania Nanotube Arrays ◽  
P Type ◽  
Flame Annealing

Elevated temperature flame and furnace annealing of anatase-phase TiO2 nanotube arrays resulted in an unusual morphological transformation that generated square-shaped annular nanostructures, and was accompanied by a change in phase from anatase to rutile. Flame annealing also improved the photoelectrochemical activity of the titania nanotubes.

Growth of TiO2 Nanotube Arrays using Porous Anodic Alumina Templates

2013 ◽  
Vol 1601 ◽  
Author(s):  
A. Shoja ◽  
A. Nourmohammadi ◽  
M. H. Feiz
Keyword(s):  
Anatase Phase ◽  
Sol Gel ◽  
Rutile Phase ◽  
Nanotube Arrays ◽  
Nanoporous Alumina ◽  
Heat Treated ◽  
Semiconductor Behavior ◽  
Dc Electric Field ◽  
Nanoporous Alumina Templates ◽  
Anodic Alumina Templates

ABSTRACTThe aim of this research study is to produce high quality TiO2 nanotube arrays. It is shown that sol-gel electrophoresis is a suitable one to obtain vast-area TiO2 nanotube arrays when nanoporous alumina templates are used. To fabricate TiO2 nanotube arrays, alumina templates were produced via a two-step anodizing by a homemade anodizing cell using high purity phosphoric acid as the electrolyte with aluminum and platinum as electrodes. The semiconductor behavior of these templates can also be employed when producing conducting substrates for the grown TiO2 nanotubes. Stabilized titanium sol was prepared by modified hydrolysis of the titanium precursor using acetic acid. In order to produce TiO2 nanotube arrays, the template pores were filled with the precursor sol by applying a DC electric field. Then, the filled template was heat treated to crystallize the desired TiO2 phase. Scanning electron microscopy of TiO2 nanotube arrays showed that the nanotubes have been deposited in the channels of the nanoporous alumina template. X-ray diffraction data confirmed phase structure and composition of TiO2 nanotube arrays after heat treatment. To reach pure anatase phase, the samples were heated at 320°C and 400°C for two hours. To obtain pure rutile phase, the samples were heated at 320°C and 750°C for two hours.

The Photocatalytic Properties of Br-Doped Titania Nanotube Arrays and its Application in Degradation of Sugar Wastewater

2013 ◽  
Vol 641-642 ◽  
pp. 11-17 ◽  
Author(s):  
Zhi Peng Meng ◽  
Fu Xin Zhong ◽  
Dan Yu Wang ◽  
Zhong Ming Zhang ◽  
Hua Ying Li ◽  
...  
Keyword(s):  
Titanium Dioxide ◽  
Photocatalytic Degradation ◽  
Uv Light ◽  
Anatase Phase ◽  
Rutile Phase ◽  
Photocatalytic Properties ◽  
Nanotube Arrays ◽  
Illumination Time ◽  
Novel Approach ◽  
Titanium Dioxide Nanotube Arrays

This paper presents a novel approach for preparing titanium dioxide nanotube arrays (TNTs) loaded with highly dispersed Br through an ultrasound aided photochemical route. The content of Br doped on the arrays was controlled by changing the concentration of NaBr and the ultrasound time. The Br doped TiO2nanotube arrays were characterized by SEM, XRD and UV–Vis spectrum. Doping the bromine did not basically affect the morphology of the surface of the TNTs, but part of the anatase phase transformed into rutile phase, which led to the formation of the mixed crystal and increased the photocatalytic activity. The results showed that Br doping significantly enhanced the photocatalytic degradation rate of titanium dioxide nanotube arrays under UV-light irradiation. The main factors which affected photocatalytic degradation of sugar wastewater were the illumination time and pH. The results showed that the longer the exposure time was, the initial pH of wastewater was more favorable to photocatalytic degradation of the sugar wastewater for the Br-TiO2nanotube arrays, and compared to undoped TiO2nanotube arrays Br doped TiO2nanotube arrays had better photocatalytic properties.

Electrochemical Fabrication and Characterization of Highly-Ordered Titania Nanotube Arrays

2010 ◽  
Vol 148-149 ◽  
pp. 1600-1606
Author(s):  
Hai Tao Zhang ◽  
Xiang Yun Deng ◽  
Xin Zheng Wu ◽  
Ri Ke Chen
Keyword(s):  
Ph Value ◽  
Anatase Phase ◽  
Nanotube Arrays ◽  
Cyclic Voltammogram ◽  
X Ray Diffraction ◽  
Titania Nanotube Arrays ◽  
Titania Nanotube ◽  
Anodic Voltage ◽  
Electrochemical Fabrication

Highly-ordered titania nanotube arrays were fabricated in ethylene glycol polar organic electrolyte containing a certain amount of sodium fluoride. Series of patterned nanotube arrays with different outside diameter and aspect ratio were obtained via optimizing anodic voltage, the concentration of fluoride ion and reaction time. The as-prepared nanotube arrays were amorphous and transformed single anatase phase characterized by X-ray diffraction with annealing under the condition of 450oC for 3h. Cyclic voltammogram behaviors were discussed using electrochemical workstation. The pH value of electrolyte, the scanning rate, the crystal structure and morphology of the samples have a significant effect on the reductive/oxidative and H+ intercalation properties.

scholarly journals One step synthesis of niobium doped titania nanotube arrays to form (N,Nb) co-doped TiO2with high visible light photoelectrochemical activity

2013 ◽  
Vol 1 (6) ◽  
pp. 2151-2160 ◽  
Author(s):  
Thomas Cottineau ◽  
Nicolas Béalu ◽  
Pierre-Alexandre Gross ◽  
Sergey N. Pronkin ◽  
Nicolas Keller ◽  
...  
Keyword(s):  
Visible Light ◽  
Nanotube Arrays ◽  
Photoelectrochemical Activity ◽  
Titania Nanotube Arrays ◽  
Niobium Doped ◽  
Titania Nanotube ◽  
One Step ◽  
Doped Titania ◽  
Co Doped

scholarly journals Photocatalytic Properties of Size-Controlled Titania Nanotube Arrays

2011 ◽  
Vol 2011 ◽  
pp. 1-7 ◽  
Author(s):  
Takeshi Hashishin ◽  
Keisuke Misawa ◽  
Kazuo Kojima ◽  
Chihiro Yogi ◽  
Jun Tamaki
Keyword(s):  
Crystallite Size ◽  
Rate Constant ◽  
Apparent Rate Constant ◽  
Anatase Phase ◽  
Ultra Violet ◽  
Tube Length ◽  
Nanotube Arrays ◽  
Titania Nanotube Arrays ◽  
Titania Nanotube ◽  
Inner Diameter

The titania nanotube arrays (TNAs) with smooth surface was synthesized by anodization of titanium foil with 3 cm2in square area using the electrolyte composed of 0.2 wt% NH4F and 0.5 vol% H2SO4in ethylene glycol in order to evaluate the methylene blue photodegradation under ultra-violet irradiation. The tube length and inner diameter as a size parameter were controlled by the anodization time from 5 to 10 h and applied voltage from 10 to 50 V. The titania nanotube arrays (TNAs) annealed at 300 to 500°C were assigned to anatase phase, and TNAs at 600°C had both phase of anatase and rutile. The crystallite size and the apparent rate constant were increased with the increase in the annealing temperature of TNAs from 300 to 500°C. The bigger crystallite size of TNAs is suggested to be related to the increase in the amount of hole at the valence band, leading to the decrease in the apparent rate constant of MB degradation. Interestingly, the four kinds of linear relationship with the apparent rate constant were seen in both the inner diameter of TNAs and the length. Consequently, the apparent rate constant strongly depended on inner diameter of TNAs.

Fabrication of Self-Organized TiO2 Nanotubes by Anodization and its Photocatalytic Properties

2011 ◽  
Vol 322 ◽  
pp. 209-212
Author(s):  
Tian Yu Wu ◽  
Xin Tan ◽  
Juan Ru Huang ◽  
Tao Yu ◽  
Lin Zhao
Keyword(s):  
Apparent Rate Constant ◽  
Photocatalytic Performance ◽  
Anatase Phase ◽  
Order Reaction ◽  
Nanotube Arrays ◽  
Photocatalytic Reaction ◽  
First Order ◽  
Self Organized ◽  
Titania Nanotube Arrays ◽  
Good Agreement

Titania nanotube arrays(TNT) was extensively studied due to its good photocatalytic activity. This article focused on the fabrication of highly ordered TNTs. TNTs were fabricated in an electrolyte of ethylene glycol(EG), water and NH4F for 1, 2, 3, 4h and then annealed at 400°C. The influence of anodic time on the morphology and photocatalytic performance of TNT was investigated. The results indicated that the TNT could be successfully fabricated by using the electrolyte, and the diameter and length of TNT were about approximately 140nm, 5-13μm, separately. Furthermore, the results also showed anatase phase was dominant, TNT with good morphology displayed good photocatalitic properties. When the initial concentration of Rhodamine B(RhB) was 7×10−6mol﹒L−1, the removal of RhB reached 88.1% by TNT anodized for 2h with length of 9.5μm. In addition, the results showed that the photocatalytic reaction fitting the first-order reaction in good agreement with the literature, and the apparent rate constant(kapp) was 0.0251 min-1(the length of 9.5μm)．

scholarly journals Preparation and High-Throughput Testing of TiO2-Supported Co Catalysts for Fischer‒Tropsch Synthesis

Catalysts ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 352
Author(s):  
Christian Schulz ◽  
Peter Kolb ◽  
Dennis Krupp ◽  
Lars Ritter ◽  
Alfred Haas ◽  
...  
Keyword(s):  
High Throughput ◽  
Anatase Phase ◽  
Rutile Phase ◽  
Tropsch Synthesis ◽  
Performance Tests ◽  
Fischer Tropsch ◽  
Fischer Tropsch Synthesis ◽  
Co Catalysts ◽  
Impregnation Technique ◽  
Co Conversion

A series of Co/TiO2 catalysts was tested in a parameters field study for Fischer‒Tropsch synthesis (FTS). All catalysts were prepared by the conventional impregnation technique to obtain an industrially relevant Co content of 10 wt % or 20 wt %, respectively. In summary, 10 different TiO2 of pure anatase phase, pure rutile phase, as well as mixed rutile and anatase phase were used as supports. Performance tests were conducted with a 32-fold high-throughput setup for accelerated catalyst benchmarking; thus, 48 experiments were completed within five weeks in a relevant operation parameters field (170 °C to 233.5 °C, H2/CO ratio 1 to 2.5, and 20 bar(g)). The most promising catalyst showed a CH4 selectivity of 5.3% at a relevant CO conversion of 60% and a C5+ productivity of 2.1 gC5+/(gCo h) at 207.5 °C. These TiO2-based materials were clearly differentiated with respect to the application as supports in Co-catalyzed FTS catalysis. The most prospective candidates are available for further FTS optimization at a commercial scale.

scholarly journals Unexpected Link between the Template Purification Solvent and the Structure of Titanium Dioxide Hollow Spheres

Catalysts ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 112
Author(s):  
Tamás Gyulavári ◽  
Kata Kovács ◽  
Klára Magyari ◽  
Kornélia Baán ◽  
Anna Szabó ◽  
...  
Keyword(s):  
Titanium Dioxide ◽  
Photocatalytic Activity ◽  
Phase Composition ◽  
Anatase Phase ◽  
Hollow Spheres ◽  
Rutile Phase ◽  
Carbon Sphere ◽  
Carbon Spheres ◽  
Carbonate Species ◽  
Determining Factor

Carbon spheres were applied as templates to synthesize titanium dioxide hollow spheres. The templates were purified with either ethanol or acetone, and the effects of this treatment on the properties of the resulting titania were investigated. The photocatalytic activity of the catalysts was measured via the decomposition of phenol model pollutant under visible light irradiation. It was found that the solvent used for the purification of the carbon spheres had a surprisingly large impact on the crystal phase composition, morphology, and photocatalytic activity. Using ethanol resulted in a predominantly rutile phase titanium dioxide with regular morphology and higher photocatalytic activity (r0,phenol = 3.9 × 10−9 M∙s−1) than that containing mainly anatase phase prepared using acetone (r0,phenol = 1.2 × 10−9 M∙s−1), surpassing the photocatalytic activity of all investigated references. Based on infrared spectroscopy measurements, it was found that the carbon sphere templates had different surface properties that could result in the appearance of carbonate species in the titania lattice. The presence or absence of these species was found to be the determining factor in the development of the titania’s properties.

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