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Photoproduction of iodine with nanoparticulate semiconductors and insulators.

Karunakaran C, Anilkumar P, Gomathisankar P - Chem Cent J (2011)

Bottom Line: Their optical edges have been obtained by UV-visible diffuse reflectance spectra.The photocatalytic activities of these oxides and also those of SiO2 and SiO2 porous to oxidize iodide ion have been determined and compared.Use of acetonitrile as medium favors the photogeneration of iodine.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Chemistry, Annamalai University, Annamalainagar 608002, Tamilnadu, India. karunakaranc@rediffmail.com.

ABSTRACT
The crystal structures of different forms of TiO2 and those of BaTiO3, ZnO, SnO2, WO3, CuO, Fe2O3, Fe3O4, ZrO2 and Al2O3 nanoparticles have been deduced by powder X-ray diffraction. Their optical edges have been obtained by UV-visible diffuse reflectance spectra. The photocatalytic activities of these oxides and also those of SiO2 and SiO2 porous to oxidize iodide ion have been determined and compared. The relationships between the photocatalytic activities of the studied oxides and the illumination time, wavelength of illumination, concentration of iodide ion, airflow rate, photon flux, pH, etc., have been obtained. Use of acetonitrile as medium favors the photogeneration of iodine.

No MeSH data available.


DRS of the oxides.
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Figure 3: DRS of the oxides.

Mentions: The diffuse reflectance spectra (DRS) of the employed oxides are shown in Figure 3. The reflectance data are presented as F(R) value, obtained by the application of Kubelka-Munk (K-M) algorithm [F(R) = (1 - R2)/2R], where R is the reflectance. The DRS clearly show that SiO2, Al2O3 and ZrO2 do not absorb UVA light. Figure 3 also displays the band gap excitation of TiO2 anatase, TiO2 P25, TiO2 Hombikat, TiO2 rutile, BaTiO3, ZnO and SnO2 under UVA radiation. The DRS further reveals that blue light is capable of effecting band gap excitation of WO3. In addition, the DRS of Fe2O3 displays the commencement of light absorption at about 600 nm itself. Also, the DRS of CuO shows that the oxide is susceptible to photoexcitation by the entire spectrum of visible light. The DRS of Fe3O4 does not show any significant variation in the measured reflectance with visible and UVA light. This is because of its reported band gap of about 0.1 eV [9]. The displayed K-M plots are in total agreement with the expected band gaps of the studied oxides [9]. The band gap of ZrO2 is very wide (about 5 eV) and Al2O3 and SiO2 are insulators and hence do not absorb in the visible and UVA region.


Photoproduction of iodine with nanoparticulate semiconductors and insulators.

Karunakaran C, Anilkumar P, Gomathisankar P - Chem Cent J (2011)

DRS of the oxides.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3141621&req=5

Figure 3: DRS of the oxides.
Mentions: The diffuse reflectance spectra (DRS) of the employed oxides are shown in Figure 3. The reflectance data are presented as F(R) value, obtained by the application of Kubelka-Munk (K-M) algorithm [F(R) = (1 - R2)/2R], where R is the reflectance. The DRS clearly show that SiO2, Al2O3 and ZrO2 do not absorb UVA light. Figure 3 also displays the band gap excitation of TiO2 anatase, TiO2 P25, TiO2 Hombikat, TiO2 rutile, BaTiO3, ZnO and SnO2 under UVA radiation. The DRS further reveals that blue light is capable of effecting band gap excitation of WO3. In addition, the DRS of Fe2O3 displays the commencement of light absorption at about 600 nm itself. Also, the DRS of CuO shows that the oxide is susceptible to photoexcitation by the entire spectrum of visible light. The DRS of Fe3O4 does not show any significant variation in the measured reflectance with visible and UVA light. This is because of its reported band gap of about 0.1 eV [9]. The displayed K-M plots are in total agreement with the expected band gaps of the studied oxides [9]. The band gap of ZrO2 is very wide (about 5 eV) and Al2O3 and SiO2 are insulators and hence do not absorb in the visible and UVA region.

Bottom Line: Their optical edges have been obtained by UV-visible diffuse reflectance spectra.The photocatalytic activities of these oxides and also those of SiO2 and SiO2 porous to oxidize iodide ion have been determined and compared.Use of acetonitrile as medium favors the photogeneration of iodine.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Chemistry, Annamalai University, Annamalainagar 608002, Tamilnadu, India. karunakaranc@rediffmail.com.

ABSTRACT
The crystal structures of different forms of TiO2 and those of BaTiO3, ZnO, SnO2, WO3, CuO, Fe2O3, Fe3O4, ZrO2 and Al2O3 nanoparticles have been deduced by powder X-ray diffraction. Their optical edges have been obtained by UV-visible diffuse reflectance spectra. The photocatalytic activities of these oxides and also those of SiO2 and SiO2 porous to oxidize iodide ion have been determined and compared. The relationships between the photocatalytic activities of the studied oxides and the illumination time, wavelength of illumination, concentration of iodide ion, airflow rate, photon flux, pH, etc., have been obtained. Use of acetonitrile as medium favors the photogeneration of iodine.

No MeSH data available.