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

Sahu M, Biswas P - Nanoscale Res Lett (2011)

Bottom Line: This has been feasible by a detailed understanding of the formation and growth of nanoparticles in the high-temperature flame region.Annealing the Cu-doped TiO2 nanoparticles increased the crystalline nature and changed the morphology from spherical to hexagonal structure.Measurements indicate a band gap narrowing by 0.8 eV (2.51 eV) was achieved at 15-wt.% copper dopant concentration compared to pristine TiO2 (3.31 eV) synthesized under the same flame conditions.

View Article: PubMed Central - HTML - PubMed

Affiliation: Aerosol and Air Quality Research Laboratory, Department of Energy, Environmental and Chemical Engineering, Washington University in St, Louis, St, Louis, MO 63130, USA. pbiswas@wustl.edu.

ABSTRACT
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 spherical to hexagonal structure. Measurements indicate a band gap narrowing by 0.8 eV (2.51 eV) was achieved at 15-wt.% copper dopant concentration compared to pristine TiO2 (3.31 eV) synthesized under the same flame conditions. The change in the crystal phase, size, and band gap is attributed to replacement of titanium atoms by copper atoms in the TiO2 crystal.

No MeSH data available.


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Schematic diagram of the FLAR experimental setup used to synthesize Cu-doped TiO2 nanoparticles.
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Figure 1: Schematic diagram of the FLAR experimental setup used to synthesize Cu-doped TiO2 nanoparticles.

Mentions: Figure 1 shows the schematic diagram of the flame aerosol reactor system used for the synthesis of the Cu-doped TiO2 nanomaterials. The main components of the flame aerosol reactor system are: a diffusion burner, a precursor feeding system, and a quenching and collection system. The design details of the diffusion burner used for this study is given in Jiang et al. [26]. Nitrogen was passed through titanium tetra-ispopropoxide (TTIP, 99.7%, Aldrich, Steinheim, Germany) in a bubbler, and the saturated vapor was introduced into the central port of the burner. The bubbler containing the liquid TTIP precursor was placed in an oil bath and was maintained at a temperature of 98°C. The precursor delivery tube was maintained at a temperature of 210°C by a heating tape. This avoided the condensation of the precursor TTIP vapor in the delivery tube. Copper nitrate trihydrate (99.5%, VWR International, Radnor, PA, USA) was used as the dopant precursor. The dopant precursor solution was prepared by dissolving a known amount of copper nitrate in distilled water. A stainless steel collison nebulizer was used to generate fine spray droplets (less than 2 μm), which were then carried by nitrogen gas into the high-temperature zone of the flame. The doping percentage was varied by introducing different molar ratios of both the precursors. The overall doping concentration was varied from 0 to 15 wt.%. Methane and oxygen were introduced into the second and third ports of the burner respectively to create a diffusion flame zone. The volumetric flow rates of N2 through the TTIP bubbler and the O2 were precisely controlled by mass flow controllers at 2 and 7.5 lpm, respectively. The methane flow rate was maintained at 1.8 lpm, and varied for few of the tests. A 20-lpm flow of compressed air was supplied in a radial direction to the quenching ring for cooling. The entrained air diluted the aerosol stream and suppressed particle growth. The synthesized materials were collected using a glass microfiber filter paper (Whatman) for further characterization.


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

Sahu M, Biswas P - Nanoscale Res Lett (2011)

Schematic diagram of the FLAR experimental setup used to synthesize Cu-doped TiO2 nanoparticles.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211860&req=5

Figure 1: Schematic diagram of the FLAR experimental setup used to synthesize Cu-doped TiO2 nanoparticles.
Mentions: Figure 1 shows the schematic diagram of the flame aerosol reactor system used for the synthesis of the Cu-doped TiO2 nanomaterials. The main components of the flame aerosol reactor system are: a diffusion burner, a precursor feeding system, and a quenching and collection system. The design details of the diffusion burner used for this study is given in Jiang et al. [26]. Nitrogen was passed through titanium tetra-ispopropoxide (TTIP, 99.7%, Aldrich, Steinheim, Germany) in a bubbler, and the saturated vapor was introduced into the central port of the burner. The bubbler containing the liquid TTIP precursor was placed in an oil bath and was maintained at a temperature of 98°C. The precursor delivery tube was maintained at a temperature of 210°C by a heating tape. This avoided the condensation of the precursor TTIP vapor in the delivery tube. Copper nitrate trihydrate (99.5%, VWR International, Radnor, PA, USA) was used as the dopant precursor. The dopant precursor solution was prepared by dissolving a known amount of copper nitrate in distilled water. A stainless steel collison nebulizer was used to generate fine spray droplets (less than 2 μm), which were then carried by nitrogen gas into the high-temperature zone of the flame. The doping percentage was varied by introducing different molar ratios of both the precursors. The overall doping concentration was varied from 0 to 15 wt.%. Methane and oxygen were introduced into the second and third ports of the burner respectively to create a diffusion flame zone. The volumetric flow rates of N2 through the TTIP bubbler and the O2 were precisely controlled by mass flow controllers at 2 and 7.5 lpm, respectively. The methane flow rate was maintained at 1.8 lpm, and varied for few of the tests. A 20-lpm flow of compressed air was supplied in a radial direction to the quenching ring for cooling. The entrained air diluted the aerosol stream and suppressed particle growth. The synthesized materials were collected using a glass microfiber filter paper (Whatman) for further characterization.

Bottom Line: This has been feasible by a detailed understanding of the formation and growth of nanoparticles in the high-temperature flame region.Annealing the Cu-doped TiO2 nanoparticles increased the crystalline nature and changed the morphology from spherical to hexagonal structure.Measurements indicate a band gap narrowing by 0.8 eV (2.51 eV) was achieved at 15-wt.% copper dopant concentration compared to pristine TiO2 (3.31 eV) synthesized under the same flame conditions.

View Article: PubMed Central - HTML - PubMed

Affiliation: Aerosol and Air Quality Research Laboratory, Department of Energy, Environmental and Chemical Engineering, Washington University in St, Louis, St, Louis, MO 63130, USA. pbiswas@wustl.edu.

ABSTRACT
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 spherical to hexagonal structure. Measurements indicate a band gap narrowing by 0.8 eV (2.51 eV) was achieved at 15-wt.% copper dopant concentration compared to pristine TiO2 (3.31 eV) synthesized under the same flame conditions. The change in the crystal phase, size, and band gap is attributed to replacement of titanium atoms by copper atoms in the TiO2 crystal.

No MeSH data available.


Related in: MedlinePlus