Growth of 1-D TiO 2 Nanowires on Ti and Ti Alloys by Oxidation (original) (raw)
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Single-crystalline rutile TiO 2 nanowires (NWs) were synthesized by the vapor-liquid-solid (VLS) method on Ti foil substrates patterned with catalytic Sn nano-islands. NWs of 3 to 8 m in length and 50 to 500 nm in diameter were grown along the [1 10] axis exhibiting a rectangular cross section with the and side facets. This facile approach to TiO 2 NW fabrication with fast induction heating and short processing time utilizes the Ti foil both as a substrate and as a metal supply, thus eliminating the need for a separate titanium source.
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TiO2 nanowires (NWs) can improve the advantageous photocatalytic properties of TiO2 by increasing the active surface area. Here we investigate the synthesis of TiO2 NWs by thermal oxidation, studying the role of temperature, annealing time, and gas flow rates. The optimal thermal growth conditions were found to be 800 °C for 4 h in a mixed gas flow of Ar and O2. Morphological and structural characterizations, carried out by scanning and transmission electron microscopy, and X-ray diffraction, indicated a TiO2 rutile monocrystalline structure of the nanowires. An in situ thermal growth analysis was performed by means of an environmental electron microscope, providing additional insights into the TiO2 NWs growth dynamics. The photocatalytic properties were studied by using the degradation rate of methylene blue under UV light. TiO2 NWs revealed a 70% improvement of the degradation rate compared to a reference TiO2 bulk sample. Moreover, NWs were additionally annealed in forming gas (5...
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Single crystalline TiO 2 nanowires have been successfully grown on alumina substrates using a high-frequency (350 KHz) dielectric heater at 1050 1C by a two-step of thermal evaporation method without using any catalyst. The first step is to form the high surface energy TiO 2 seeds on the low surface energy alumina substrates. The second step is to grow the single crystalline TiO 2 nanowires on the alumina substrates by the vapor-solid (VS) mechanism. The field emission electron microscopy (FESEM) image showed a uniform diameter of 60-90 nm and length of hundreds of nm to 2 mm for the TiO 2 nanowires. The high-resolution transmission electron microscopy (HRTEM) image showed that the TiO 2 nanowires are of single crystalline rutile structure. The luminescence properties were investigated by cathodoluminescence (CL) in FESEM. The result is surprising in that the TiO 2 nanowires are of rutile phase, but the luminescence properties similar to the bulk TiO 2 of anatase phase. r
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Herein, we report the catalyst assisted growth of TiO2 one-dimensional (1D) nanowires (NWs) on alumina substrates by the thermal oxidation technique. RF magnetron sputtering was used to deposit a thin Ti metallic layer on the alumina substrate, followed by an Au catalytic layer on the Ti metallic one. Thermal oxidation was carried out in an oxygen deficient environment. The optimal thermal growth temperature was 700 °C, in a mixture environment composed by Ar and O2. As a comparison, Ti films were also oxidized without the presence of the Au catalyst. However, without the Au catalyst, no growth of nanowires was observed. Furthermore, the effect of the oxidation temperature and the film thickness were also investigated. SEM, TEM, and EDX studies demonstrated the presence of Au nanoparticles on top of the NWs, indicating that the Au catalyst drove the growth process. Raman spectroscopy revealed the Rutile crystalline phase of TiO2 NWs. Gas testing measurements were carried out in the ...
Synthesis of TiO 2 Nanowires via Hydrothermal Method
Japanese Journal of Applied Physics, 2012
Titanium dioxide (TiO 2) nanowires have been successfully synthesized by a simple, rapid, inexpensive, and novel approach based on a hydrothermal method. The use of hydrothermal treatment on TiO 2 nanopowder as a precursor with highly concentrated sodium hydroxide for 6 h produced a novel nanostructure of TiO 2 nanowires. The field-emission scanning electron microscopy (FESEM) image shows that the synthesized TiO 2 nanowires are very abundant in quantity with diameters ranging from 8.0-14 nm and are extra long. X-ray diffraction (XRD) result indicates that the synthesized TiO 2 nanowires are mainly composed of anatase phase with a minor of rutile phase. These properties of nanowires promise a broad range of applications in electronic devices.
MATEC Web of Conferences, 2015
We have investigated TiO2 nanostructures prepared by anodization in conjunction with hydrothermal method using Ti metal plates. The TiO2 nanoporus were fabricated by electrochemical anodization in a NH4F/EG4/H2O electrolyte system. Ultrasonic wave was used to clean the surface of TiO2 nanoporus in the medium of water after completing the anodization. After drying in air, the nanoporusarrays were calcined at 450 °C for 2 h in air. The TiO2 nanostructures were converted by hydrothermal in air.The TiO2 nanostructures were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). XRD patterns show the TiO2 anatase structure. SEM images indicate that the TiO2 structures depend on preparation temperatures. The density of TiO2 nanostructures increases as the time increases. The growth of TiO2 nanostructures was observed to be times dependence. The nanostructures are nanowires and nanospikes when the peraring time was 18 h, nanoflowers when the preparing time was 24h. This approach provides the capability of creating patterned 1D TiO2 nanowires at 18h. The diameter of TiO2 nanowires varies from 20 nm to 25 nm and length of several 250 nm.
Nano Letters, 2009
The mechanisms governing the tensile behavior of TiO 2 nanowires were studied by molecular dynamics simulations. Nanowires below a threshold diameter of about 10 Å transformed into a completely disordered structure after thermodynamic equilibration, whereas thicker nanowires retained their crystalline core. Initial elastic tensile deformation was effected by the reconfiguration of surface atoms while larger elongations resulted in continuous cycles of Ti-O bond straightening, bond breakage, inner atomic distortion, and necking until rupture. Nanowires have much better mechanical properties than bulk TiO 2. Nanowires below the threshold diameter exhibit extraordinarily high stiffness and toughness and are more sensitive to strain rate.
Depositional Characteristics of Metal Coating on Single-Crystal TiO2 Nanowires
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