Limits...
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.


Related in: MedlinePlus

TEM images of annealed Cu-doped TiO2 samples. (a) 1 wt.% Cu-TiO2 and (b) 15 wt.% Cu-TiO2. Annealing temperature, 600°C; duration of annealing, 4 h (test 3).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC3211860&req=5

Figure 9: TEM images of annealed Cu-doped TiO2 samples. (a) 1 wt.% Cu-TiO2 and (b) 15 wt.% Cu-TiO2. Annealing temperature, 600°C; duration of annealing, 4 h (test 3).

Mentions: The HR-TEM images of samples annealed at 600°C are shown in Figure 9. The figure indicates that the annealed 1-wt.% Cu-doped TiO2 particle was completely crystallized with no discontinuity in the crystal fringes as observed from HR-TEM images, similar to the as-prepared 1-wt.% Cu-doped TiO2 particles. However, for the 15-wt.% dopant sample, some amorphous regions were still detected as shown in Figure 9 (highlighted with the white squares). More detailed investigations are needed to understand the effect of dopant concentration and reaction environments on morphology change during post-synthesis treatment of the initially synthesized spherical particles. The UV-vis measurements of absorption spectra of 1- and 15-wt.% Cu-doped TiO2 annealed samples are shown in Figure 10 and compared with the commercially available CuO nanoparticles. Annealing of the 15 wt.% Cu-TiO2 increased the absorption compared to the as prepared samples in the visible spectrum mainly because of enhanced crystalline CuO formation. It is clear from the results that post-synthesis annealing can alter the doped TiO2 nanomaterial properties such as size, crystal structures as well as absorption properties, thus influencing eventual functionality and performance.


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

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

TEM images of annealed Cu-doped TiO2 samples. (a) 1 wt.% Cu-TiO2 and (b) 15 wt.% Cu-TiO2. Annealing temperature, 600°C; duration of annealing, 4 h (test 3).
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 9: TEM images of annealed Cu-doped TiO2 samples. (a) 1 wt.% Cu-TiO2 and (b) 15 wt.% Cu-TiO2. Annealing temperature, 600°C; duration of annealing, 4 h (test 3).
Mentions: The HR-TEM images of samples annealed at 600°C are shown in Figure 9. The figure indicates that the annealed 1-wt.% Cu-doped TiO2 particle was completely crystallized with no discontinuity in the crystal fringes as observed from HR-TEM images, similar to the as-prepared 1-wt.% Cu-doped TiO2 particles. However, for the 15-wt.% dopant sample, some amorphous regions were still detected as shown in Figure 9 (highlighted with the white squares). More detailed investigations are needed to understand the effect of dopant concentration and reaction environments on morphology change during post-synthesis treatment of the initially synthesized spherical particles. The UV-vis measurements of absorption spectra of 1- and 15-wt.% Cu-doped TiO2 annealed samples are shown in Figure 10 and compared with the commercially available CuO nanoparticles. Annealing of the 15 wt.% Cu-TiO2 increased the absorption compared to the as prepared samples in the visible spectrum mainly because of enhanced crystalline CuO formation. It is clear from the results that post-synthesis annealing can alter the doped TiO2 nanomaterial properties such as size, crystal structures as well as absorption properties, thus influencing eventual functionality and performance.

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