Formation and mechanistic study of self-ordered TiO2 nanotubes on Ti substrate

Kang, Soon Hyung; Kim, Jae-Yup; Kim, Hyun Sik; Sung, Yun Mo

doi:10.1016/j.jiec.2007.06.004

Cited by 73 publications

(33 citation statements)

References 38 publications

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“…It is believed that the surface overlayer represents the un-dissolved compact/barrier oxide layer that was formed in the initial stages of the anodization process. 29 In comparison, Figure 1b shows what appears to be a very similar structure for the nitrided NTs, formed after 7 h of ammonolysis of the Ta oxide NTs at 700 o C. These NTs, which are now an orange-yellow color, are still roughly 40 nm in diameter, similar to what is seen for the Ta oxide NT precursor ( Figure 1a). Also, they appear to have adhered very well to the Ta substrate during exposure to the high temperatures required to form TaO x N y , as the Ta surface is still essentially fully covered by the nanotubular array.…”

Section: Resultssupporting

confidence: 55%

Conductivity Switching of N-Doped Ta Oxide Nanotubular Arrays

Abhayawardhana

Birss

2015

J. Phys. Chem. C

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Ta oxynitride (TaO x N y ) nanotubes (NTs) were synthesized by the anodization of Ta in an aqueous H 2 SO 4 + HF solution, forming Ta oxide NTs, followed by the high temperature conversion of Ta oxide to TaO x N y in ammonia. The electrochemical behavior of these nanotubular arrays was then investigated using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), revealing a wide range of interesting properties. The Ta oxynitride NTs, which are shown to contain evenly spaced holes along their length, undergo a reversible redox process involving cation intercalation in both aqueous solutions and dry acetonitrile at potentials negative of 0.5 V, while above this, the nanotubular array is nonconducting. From the CV charges, it is possible that this reaction occurs only on the exposed TaO x N y NT surfaces, although the nanotubular array does undergo conductivity and colour switching. EIS analysis has confirmed the pseudocapacitive properties of the TaO x N y NTs at < 0.5 V, while at potentials above this, Mott-Schottky analysis shows that they are n-type semiconductors having a donor density of ca. 6  10 21 cm -3 .

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Section: Resultssupporting

confidence: 55%

Conductivity Switching of N-Doped Ta Oxide Nanotubular Arrays

Abhayawardhana

Birss

2015

J. Phys. Chem. C

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“…[26][27][28][29] These promising prospects require a thorough understanding of the nanotube formation mechanism and controllable preparation of the arrays. Many reports briefly mentioned the growth mechanism of TiO 2 nanotube arrays, [30][31][32][33][34] in which the key processes of the nanotube growth were described as follows: (i) Oxide growth at the surface of the metal due to interaction of the metal with O 2-or OH -. (ii) Metal ion (Ti 4+ ) migration from metal foil at the metal-oxide interface; Ti 4+ cations ejected from the metal-oxide interface under the application of an electric field move toward the oxide-electrolyte interface.…”

Section: Introductionmentioning

confidence: 99%

“…35 Normally, the current curve recorded during anodization is a convenient way to characterize the electrochemical behavior and the tube growth process. 7,15,17,18,21,31,36,37 Figure 1 shows a typical current-time transient for the anodization of Ti foil, in which three stages can be easily classified. After an initial exponential decay (stage I), the current increases for a short time (stage II), then the current reaches a quasi-steady state (stage III).…”

Section: Introductionmentioning

confidence: 99%

Current characterization and growth mechanism of anodic titania nanotube arrays

Cao

Wang

et al. 2011

J. Mater. Res.

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TiO 2 nanotube arrays were synthesized by anodic oxidation on a pure titanium substrate in solutions containing 0.175 M NH 4 F composed of mixtures with different volumetric ratios of DI water and glycerol. According to the results of the current curve recorded during anodization, the time of the first sharp current slope (corresponding to the initial oxide layer formation time) was found to vary from 8 to 171 s depending not only upon the water content in the electrolytes but also upon the voltage. The current curves exhibit oscillation with different amplitudes and periods. In combination with the scanning electron microscope (SEM) images, a growth mechanism, layer-by-layer model, of TiO 2 nanotube arrays was presented. Based on this mechanism, many phenomena that appeared during anodization can be reasonably explained. Our results would be helpful for the design of nanoarchitectures in related material systems.

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“…Además de sus propiedades fotoconductoras, sus características texturales y estructurales, en conjunto con su cristalinidad, desempeñan un papel importante dentro de cualquier proceso catalítico (9,10). Aparentemente la eficiencia de las reacciones fotocatalíticas son inducidas por una deseable área específica y en el caso del TiO 2 por su fase anatasa estabilizada (11).…”

Section: Introductionunclassified

Síntesis, caracterización y actividad fotocatalítica de óxido de titanio modificado con nitrógeno

Enríquez¹,

García-Alamilla²,

Serrano³

et al. 2011

Bol. Soc. Esp. Ceram. Vidr.

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Se sintetizaron óxidos de titanio (TiO 2 ) a partir de la precipitación del tetracloruro de titanio (TiCl 4 ) con hidróxido de amonio (NH 4 OH). Los materiales sintetizados se caracterizaron mediante fisisorción de nitrógeno, difracción de rayos X, espectroscopía infrarroja, reflectancia difusa U.V.-visible y la actividad fotocatalítica de los mismos se evaluó en la degradación del naranja de metilo. Mediante el método de síntesis se logró dopar la estructura del óxido de titanio con nitrógeno (N-TiO 2 ), estabilizando la fase anatasa y obteniéndose materiales catalíticos mesoporosos y nanocristalinos. El óxido de titanio de mayor área específica (132 m 2 /g) degradó el azo-colorante al 100% en 180 minutos de reacción. Palabras clave: síntesis, óxidos de titanio, materiales mesoporosos, materiales nanocristalinos, azo-compuestoSynthesis, characterization and photocatalytic activity of titanium oxide modified with nitrogen Titanium oxides (TiO 2 ) were synthesized by precipitation of titanium tetrachloride (TiCl 4 ) using ammonium hydroxide (NH 4 OH). The synthesized materials were characterized by means of nitrogen physisorption, X-ray diffraction, infrared spectroscopy, U.V.-visible diffuse reflectance spectroscopy and the photocatalytic activity of the samples were measured by the degradation of the methyl orange. By means of this synthesis method we have doped the titanium oxide structure with nitrogen (N-TiO 2 ), stabilizing the anatase phase and obtaining mesoporous and nanocrystalline materials. The titanium oxide with higher specific surface area (132 m 2 /g) degraded the azo-compound to 100% in 180 min of reaction. Keywords: synthesis, titanium oxides, mesoporous materials, nanocrystalline materials, azo-compound INTRODUCCIÓNLos efluentes de la industria textil presentan un gran potencial de impacto sobre el medio ambiente, debido a los grandes volúmenes de agua residual generados con un alto contenido de materia orgánica y una fuerte coloración. A causa de la gran estabilidad de los colorantes (azocompuestos), los procesos convencionales para el tratamiento de aguas residuales tales como adsorción, floculación y procesos de lodos activados no son eficientes para la decoloración de los efluentes textileros, ya que no pueden degradar eficientemente los compuestos orgánicos o generan contaminantes secundarios que pueden ser tóxicos para el medio ambiente y que requieren de un tratamiento adicional (1-3). Una alternativa al tratamiento convencional de las aguas residuales es la oxidación fotocatalítica (fotocatálisis), la cual, ha despertado un gran interés debido a que las investigaciones han mostrado la degradación de contaminantes orgánicos a bajas y medianas concentraciones, con una generación baja en contaminantes secundarios. La fotocatálisis heterogénea consiste en la degradación del contaminante a través de la utilización de catalizadores (óxidos semiconductores), radiación ultravioleta y/o solar, generando con ello radicales Vol 50, 5, 245-252, Septiembre-Octubre 2011 ISSN 0366-3175. eISSN 2173-043...

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Formation and mechanistic study of self-ordered TiO2 nanotubes on Ti substrate

Cited by 73 publications

References 38 publications

Conductivity Switching of N-Doped Ta Oxide Nanotubular Arrays

Conductivity Switching of N-Doped Ta Oxide Nanotubular Arrays

Current characterization and growth mechanism of anodic titania nanotube arrays

Síntesis, caracterización y actividad fotocatalítica de óxido de titanio modificado con nitrógeno

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