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Single-step processing of copper-doped titania nanomaterials in a flame aerosol reactor

Nanoscale Research Letters, 2011

Synthesis and characterization of long wavelength visible-light absorption Cu-doped TiO2 nanomaterials with well-controlled properties such as size, composition, morphology, and crystal phase have been demonstrated in a single-step flame aerosol reactor. This has been feasible by a detailed understanding of the formation and growth of nanoparticles in the high-temperature flame region. The important process parameters controlled were: molar feed ratios of precursors, temperature, and residence time in the high-temperature flame region. The ability to vary the crystal phase of the doped nanomaterials while keeping the primary particle size constant has been demonstrated. Results indicate that increasing the copper dopant concentration promotes an anatase to rutile phase transformation, decreased crystalline nature and primary particle size, and better suspension stability. Annealing the Cu-doped TiO2 nanoparticles increased the crystalline nature and changed the morphology from spher...

SSynthesis of Nanostructured Copper-doped Titania and Its Properties

Nanostructured pure-TiO2 and Cu3%-TiO2 were successfully synthesized via co-precipitation method. The X-ray diffraction (XRD) result proves that the synthesized sample were predominantly in anatase phase with size in the range of 8∼16 nm, which are in good agreement with the transmission electron microscopy data. Owing to doping of copper, not only did the thermal stability of the TiO2 decrease, but also a significant decrease in its particle size and a shift of the adsorption edge to a higher wavelength region appear. The activity of both pure-TiO2 and Cu3%-doped TiO2 was tested to study their ability to decolorize congo red (CR) dye in aqueous solution. We observed that the CR dye was decolorized faster by Cu3%-TiO2 than pure-TiO2. Results of this study demonstrate a potential application of the synthesized sample for decolorizing dye pollutants from aqueous waste. (Official), oman.zuas@yahoo.co.id (General) Nano-Micro Lett. 5(1), 26-33 (2013)/ http://dx.doi.org/10.3786/nml.v5i1.p26-33

Carbon-coated titania nanostructured particles: Continuous, one-step flame-synthesis

Journal of Materials Research, 2003

Concurrent synthesis of titania-carbon nanoparticles (up to 52 wt.% in C) was studied in a diffusion flame aerosol reactor by combustion of titanium tetraisopropoxide and acetylene. These graphitically layered carbon-coated titania particles were characterized by high-resolution transmission electron microscopy (HRTEM), with elemental mapping of C and Ti, x-ray diffraction (XRD), and nitrogen adsorption [Brunauer-Emmett-Teller (BET)]. The specific surface area of the powder was controlled by the acetylene flow rate from 29 to 62 m2/g as the rutile content decreased from 68 to 17 wt.%. Light blue titania suboxides formed at low acetylene flow rates. The average XRD crystal size of TiO2 decreased steadily with increasing carbon content of the composite powders, while the average BET primary particle size calculated from nitrogen adsorption decreased first and then approached a constant value. The latter is attributed to the formation of individual carbon particles next to carbon-coate...

Synthesis of non-aggregated titania nanoparticles in atmospheric pressure diffusion flames

Powder Technology, 2006

Flame aerosol synthesis has been employed to synthesize nanoscale titania (TiO 2 ) particles by oxidation of titanium tetraisopropoxide (TTIP) vapor. The influence of reactant mixing and flow rates on particle morphology, size and phase composition has been studied for two different diffusion flame configurations using transmission electron microscopy, X-ray diffraction and photon correlation spectroscopy. Spherical, loosely agglomerated powders with a minimum secondary particle size of 90 nm and a rutile content of up to 35 w % were obtained at low oxygen flow rates in the double diffusion flame, while large anatase-rich aggregates formed at high oxygen flow rates. It is shown that the degree of aggregation of the as-synthesized particles is represented better by the ratio of d PCS 3 /d TEM 3 , than by the ratio of d BET 3 /d XRD 3 commonly used in literature. The differences observed in particle morphology and phase composition can be explained by considering their time-temperature history as a function of flame configuration and gas flow rates.

Characterization and sinterability of nanophase titania particles processed in flame reactors

Nanostructured Materials, 1996

Flame aerosol reactors are a routefor large scale processing of nanostructured materials. However, fundamentals about processing-structure-property relationships have not been extensively researched. This work utilized three dtflerent burners to obtain a wide range of flame processing conditions (different time-temperature histories) to study the formation of nanophase titaniaparticles. At low precursor reaction temperatures of about 400 "C, amorphous titania wasobtained. At intermediate temperaturesof900-1430"C,mixturesof anataseandrutile phase titania were obtained. At high temperatures of 1500-157O"C, spherical particles of 100% anatase titania were obtained. A qualitative explanation of the dtfferentphaseformation has been provided. Transmission Electron Microscopy was used to study particle morphology, size and agglomeration. Sizes of the titania particles produced by the designed burners variedfrom 10 to 100 nm, depending on processing conditions. In situ light scattering measurements were made to examine the evolution of the particle sizes. Post-sintering experiments were carried out to illustrate superior sinterability of the nanophase titania powders.

Characteristics of Titania Nanoparticles Synthesized Through Low Temperature Aerosol Process

2005

As one of the important process alternatives for the synthesis of nano materials with lower costs, flexibility and versatility, vapor phase synthesis of titania nano particles continue to attract attention. A low temperature aerosol process for the synthesis of titania nano particles is demonstrated by elucidating the influence of temperature, molar ratio of H 2 O/TiCl 4 and concentration of precursors on particle size and phase composition. This paper highlights the advantages of employing amorphous phase titania powder as solid precursor for its transformation to the rutile phase at temperatures less than 973K through vapor phase hydrolysis of TiCl 4. A mechanistic hypothesis is proposed to explain the catalytic role of water vapor in the enhancement of amorphous to anatase phase transformation at high (15 to 27) molar ratio of H 2 O/TiCl 4 .