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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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Zeta potential measurements of Cu-doped TiO2 nanoparticles in aqueous suspension.
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Figure 5: Zeta potential measurements of Cu-doped TiO2 nanoparticles in aqueous suspension.

Mentions: The dispersion characteristics of nanoparticles in aqueous suspensions influence the fate and transport, catalytic reactivity in the environmental system as well as critical in understanding for toxicological applications [38,39]. The stability of the synthesized Cu-doped TiO2 nanoparticles was analyzed through the measurement of zeta potential in aqueous system using de-ionized water suspension (Figure 5) and compared with pure TiO2 (test 1A) and commercial CuO. When metal oxide nanoparticles are dispersed in water, the hydration of the nanoparticle surface followed by protonation and deprotonation of the surface groups from the oxide surface results in a surface charge. The effective surface charge on the particle depends on the isoelectric point (IEP) in the suspension [39,40]. The zeta potential observed for pure TiO2 particle was +3.4 mV in the suspension, as the measured pH of the suspension was 5.06, which is less than the IEP of the TiO2(pH approximately 6.0) and consistent with other studies [40]. However, for Cu-doped TiO2 nanoparticles, the zeta potential value decreased to -3.4 mV and -25.6 mV at 1-wt.% (test 1B) and 15-wt.% (test 1F) copper dopant concentration. The zeta potential measured for the commercial CuO was -27.3 mV which is close to the zeta potential value observed for 15-wt.% Cu-TiO2 samples (test 1F). The high surface charge on the 15 wt.% Cu-TiO2 indicates better stability of these particles over pristine TiO2 nanoparticles in aqueous suspension. The higher zeta potential value and suspension stability of the doped nanoparticles compared to TiO2 is attributed to charge imbalance created due to substitution of Ti4+ atoms by Cu2+ in the TiO2 structure resulting in a more negatively charged surface. Furthermore, zeta potential values for 15-wt.% Cu-TiO2 samples being similar to pure CuO supports the presence of a copper oxide layer on the outer surface of the particles.


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

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

Zeta potential measurements of Cu-doped TiO2 nanoparticles in aqueous suspension.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 5: Zeta potential measurements of Cu-doped TiO2 nanoparticles in aqueous suspension.
Mentions: The dispersion characteristics of nanoparticles in aqueous suspensions influence the fate and transport, catalytic reactivity in the environmental system as well as critical in understanding for toxicological applications [38,39]. The stability of the synthesized Cu-doped TiO2 nanoparticles was analyzed through the measurement of zeta potential in aqueous system using de-ionized water suspension (Figure 5) and compared with pure TiO2 (test 1A) and commercial CuO. When metal oxide nanoparticles are dispersed in water, the hydration of the nanoparticle surface followed by protonation and deprotonation of the surface groups from the oxide surface results in a surface charge. The effective surface charge on the particle depends on the isoelectric point (IEP) in the suspension [39,40]. The zeta potential observed for pure TiO2 particle was +3.4 mV in the suspension, as the measured pH of the suspension was 5.06, which is less than the IEP of the TiO2(pH approximately 6.0) and consistent with other studies [40]. However, for Cu-doped TiO2 nanoparticles, the zeta potential value decreased to -3.4 mV and -25.6 mV at 1-wt.% (test 1B) and 15-wt.% (test 1F) copper dopant concentration. The zeta potential measured for the commercial CuO was -27.3 mV which is close to the zeta potential value observed for 15-wt.% Cu-TiO2 samples (test 1F). The high surface charge on the 15 wt.% Cu-TiO2 indicates better stability of these particles over pristine TiO2 nanoparticles in aqueous suspension. The higher zeta potential value and suspension stability of the doped nanoparticles compared to TiO2 is attributed to charge imbalance created due to substitution of Ti4+ atoms by Cu2+ in the TiO2 structure resulting in a more negatively charged surface. Furthermore, zeta potential values for 15-wt.% Cu-TiO2 samples being similar to pure CuO supports the presence of a copper oxide layer on the outer surface of the particles.

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