Synthesis of anatase TiO2 nanotubes derived from a natural leucoxene mineral by the hydrothermal method (original) (raw)
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One-Step Hydrothermal Synthesis of Anatase TiO2 Nanotubes for Efficient Photocatalytic CO2 Reduction
ACS omega, 2022
The hydrothermal dissolution-recrystallization process is a key step in the crystal structure of titania-based nanotubes and their composition. This work systematically studies the hydrothermal conditions for directly synthesizing anatase TiO 2 nanotubes (ATNTs), which have not been deeply discussed elsewhere. It has been well-known that ATNTs can be synthesized by the calcination of titanate nanotubes. Herein, we found the ATNTs can be directly synthesized by optimizing the reaction temperature and time rather than calcination of titanate nanotubes, where at each temperature, there is a range of reaction times in which ATNTs can be prepared. The effect of NaOH/TiO 2 ratio and starting materials was explored, and it was found that ATNTs can be prepared only if the precursor is anatase TiO 2 , using rutile TiO 2 leads to forming titanate nanotubes. As a result, ATNTs produced directly without calcination have excellent photocatalytic CO 2 reduction than titanate nanotubes and ATNTs prepared by titanate calcination.
Materials Research Bulletin, 2006
Photocatalytic performance of a hydrothermally synthesized pure anatase TiO 2 with 8 nm average crystallite size for decomposition of Reactive Red 141 was examined by investigating the effects of UV-light irradiation time, irradiation power, amount of TiO 2 and initial dye concentration. Change in the UV absorbance of the dye during irradiation was monitored. One wt.% TiO 2 in 30 mg/l Reactive Red 141 aqueous solution was found adequate for complete decolorization in 70 min at 770 W/m 2 irradiation power. It was realized that, compared to Degussa P-25, the synthesized nano-TiO 2 can be repeatedly used as a new catalyst. The results also proved that Reactive Red 141 is decomposed catalytically due to the pseudo first-order reaction kinetics. #
Eastern-European Journal of Enterprise Technologies
Ilmenite (FeTiO3) is a suitable mineral to produce titanium dioxide (TiO2) for photocatalyst applications. Therefore, this research was conducted to synthesize TiO2 material from titanium oxysulfate (TiOSO4) extracted from Indonesia local ilmenite mineral (FeTiO3) and to modify this material into TiO2 nanotubes through a hydrothermal process at 150 °C for 24 hours followed by a post-hydrothermal treatment with temperature variations of 80,100, 120, and 150 °C for 12 hours. The purpose was to investigate the effect of the post-hydrothermal variations on the crystal structure, morphology, and optical properties of the TiO2 nanotubes produced. It was discovered from the scanning electron microscopy (SEM) observations that the TiO2 nanotube was successfully derived from the ilmenite precursor. Moreover, the X-Ray diffraction (XRD) analysis of the nanotube crystal structure showed that post-hydrothermal treatment enhanced the crystallinity of the anatase TiO2 phase even though the sodium...
Synthesis and Photocatalytic Activity of Anatase TiO2 Nanoparticles-coated Carbon Nanotubes
Nanoscale Research Letters, 2010
A simple and straightforward approach to prepare TiO 2-coated carbon nanotubes (CNTs) is presented. Anatase TiO 2 nanoparticles (NPs) with the average size *8 nm were coated on CNTs from peroxo titanic acid (PTA) precursor even at low temperature of 100°C. We demonstrate the effects of CNTs/TiO 2 molar ratio on the adsorption capability and photocatalytic efficiency under UV-visible irradiation. The samples showed not only good optical absorption in visible range, but also great adsorption capacity for methyl orange (MO) dye molecules. These properties facilitated the great enhancement of photocatalytic activity of TiO 2 NPs-coated CNTs photocatalysts. The TiO 2 NPs-coated CNTs exhibited 2.45 times higher photocatalytic activity for MO degradation than that of pure TiO 2 .
Titanium dioxide (TiO2) nanotubes was synthesized by hydrothermal method and calcined at different temperature (300, 400, 500, 700°C) for 2 hours to study the effect of different calcination temperature on the physical properties and photocatalytic activity of TiO2 nanotubes was studied. The anatase phase structure of the TiO2 nanotubes is remained even after calcination at highest temperature studied of 700 °C. However, their morphological structure transformed from nanotubes into nanoparticles after calcination at higher temperature. Hence, reduces the photocatalytic activity of TiO2 material in degrading methyl orange due to the decreases in surface area and porosity of the materials.
A facile synthesis of nanocrystalline anatase TiO2 from TiOSO4 aqueous solution
A green and simple synthetic route via a thermal hydrolysis of titanyl sulphate (TiOSO4) has been employed to prepare nanocrystalline anatase titanium dioxide (TiO2) without further calcination. X-ray diffraction (XRD) clearly showed that the anatase crystalline structure was already formed under the reaction conditions at 80.0±2.0 °C. The obtained anatase TiO2 showed high thermal stability as the anatase-to-rutile transformation in only 25 wt% occurred at 900 °C. Scanning electron (SEM) and transmission electron (TEM) micrographs revealed that TiO2 secondary particles comprised irregular primary particles with diameters of 8–22 nm depending on the calcination temperature. Superior UV-light absorption intensity compared with the commercial P25 TiO2suggested the great potential of the obtained material for use as a highly efficient photocatalyst under UV irradiation.
A new solvent-exchange technique to prepare anatase nanoparticles with exceptional thermal stability and photocatalytic activity is described here. The process of preparation is accomplished by using organic solvents to precipitate hydrous titania particles from a basic aqueous medium containing a titanium peroxo complex. Undoped titanium dioxide formed via a solvent exchange method has unprecedented thermal stability against transformation to the rutile phase, as opposed to TiO 2 prepared by the common method of the gelation of an aqueous titanium peroxo complex. On the basis of X-ray thermodiffraction experiments, it has been established that the thermal treatment at 1000 C of the titania prepared by ethanol precipitation contains 100% pure anatase phase. The stabilization of anatase is induced by the high defectiveness of the TiO 2 nanostructure, which is evidenced from band-gap energy estimation, PXRD and HRTEM studies. The prepared TiO 2 nanoparticles show an outstanding photocatalytic activity comparable to the commercial Aeroxide P25 photocatalyst in the UV-assisted decomposition of methylene blue.
Synthesis and characterization of pure anatase TiO 2 nanoparticles
Journal of Materials Science-materials in Electronics, 2011
Pure anatase TiO2 nanoparticles were synthesized by microwave assisted sol–gel method and further characterized by powder X-ray diffraction (XRD), energy dispersive x-ray analysis (EDAX), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and UV–Visible spectrophotometer, SEM images showed that TiO2 nanoparticles were porous structure. The XRD patterns indicated that TiO2 after annealed at 300 °C for 3 h was mainly pure anatase phase. The crystallite size was in the range of 20–25 nm, which is consistent with the results obtained from TEM images. Microwave heating offers several potential advantages over conventional heating for inducing or enhancing chemical reactions.
Layered titanate nanotubes (TTNT) with a general formula Na x H 2-x Ti 3 O 7 ‚nH 2 O were synthesized by hydrothermally reacting TiO 2 -anatase with NaOH at 120°C. Detailed TGA and XRD characterization indicated that the as-synthesized material rich in sodium as an interlayer cation contained intercalated water (n), which was reduced substantially after nearly complete proton exchange (x ) ∼0), while the interlayer distance decreased approaching the interlayer distance d 200 of H 2 Ti 3 O 7 . Chemical composition and crystal structure of TTNT as well as their dependence on sodium content were not affected by the crystallite size of the starting anatase. On the other hand, TEM examination and N 2 adsorption measurements revealed distinct morphology at the nanometer scale and different textural properties depending on the precursor TiO 2 . Such dependence was rationalized based on a dissolutionrecrystallization mechanism.
Applied Catalysis B-environmental, 2005
Nanosized titanium dioxide photocatalysts with varying amount of anatase and rutile phases have been synthesized. Homogeneous precipitation of aqueous solutions containing TiOSO 4 with urea was used to prepare porous spherical clusters of anatase TiO 2. Photoactive titania powders with variable amount of anatase and rutile phases were prepared by heating of pure anatase in the temperatutre range 800-1150 8C. The structure evolution during heating of the starting anatase powders was studied by XRD analysis in overall temperature range of phase transformation. The morphology and microstucture characteristics were also obtained by HRTEM, BET and BJH. The spherical particle morphology of TiO 2 mixtures determined by SEM was stable in air up to 900 8C. The photocatalytic activity of the sample titania TIT85/825 heated to 825 8C in air, contained 77.4% anatase and 22.6% rutile was higher than that nanocrystalline anatase powder. Titania sample TIT85/ 825 reveals the highest catalytic activity during the photocatalyzed degradation of 4-chlorophenol in aqueous suspension. #