A new coprecipitation/hydrolysis synthesis route is used to create aTiO2-ZnFe2O4nanocomposite that is directed towards extending the photoresponse ofTiO2from UV to visible wavelengths (>400 nm). The effect ofTiO2's accelerated anatase-rutile phase transformation due to the presence of the coupledZnFe2O4narrow-bandgap semiconductor is evaluated. The transformation's dependence on pH, calcinations temperature, particle size, andZnFe2O4concentration has been analyzed using XRD, SEM, and UV-visible spectrometry. The requirements for retaining the highly photoactive anatase phase present in aZnFe2O4nanocomposite are outlined. The visible-light-activated photocatalytic activity of theTiO2-ZnFe2O4nanocomposites has been compared to an AldrichTiO2reference catalyst, using a solar-simulated photoreactor for the degradation of phenol.
Nanostructured colloidal semiconductors with heterogeneous photocatalytic behavior have drawn considerable attention over the past few years. This is due to their large surface area, high redox potential of the photogenerated charge carriers, and selective reduction/oxidation of different classes of organic compounds. In the present paper, we have carried out a systematic synthesis of nanostructured CdS-TiO2via reverse micelle process. The structural and microstructural characterizations of the as-prepared CdS-TiO2nanocomposites are determined using XRD and SEM-EDS techniques. The visible light assisted photocatalytic performance is monitored by means of degradation of phenol in water suspension.
The wide bandgap semiconductor TiO 2 has become the dominant UV-activated photocatalyst in the field of air and water detoxification because of its high stability, low cost, high oxidation potential and chemically favorable properties. The demand for visible-light activated photocatalytic systems is increasing rapidly; however, currently, the efficiency and availability of photocatalysts that can be activated effectively by the solar spectrum and particularly indoor lighting is severely limited. In this paper, a new coprecipitation/hydrolysis synthesis route is used to create a TiO 2 -ZnFe 2 O 4 nanocomposite that is directed towards extending the photoresponse of TiO 2 from UV to visible wavelengths (>400nm). The effect of TiO 2 's accelerated anatase-rutile phase transformation due to the presence of the coupled ZnFe 2 O 4 narrow bandgap semiconductor is evaluated. The transformation's dependence on pH, calcination temperature, particle size, and ZnFe 2 O 4 concentration has been analyzed using XRD, SEM, and UV-Visible spectrometry. The requirements for retaining the highly photoactive anatase phase present in a ZnFe 2 O 4 nanocomposite are outlined. The visiblelight activated photocatalytic activity of the TiO 2 -ZnFe 2 O 4 nanocomposites have been compared to an Aldrich TiO 2 reference catalyst, using a solar-simulated photoreactor for the degradation of phenol.
Nano-structured colloidal semiconductors with heterogeneous photocatalytic behavior have drawn considerable attention over the past few years. This is due to their large surface area, high redox potential of the photogenerated charge carriers and selective reduction/oxidation of different class of organic compounds. Nano-structured TiO2 is widely used as a photocatalyst for the effective decomposition of organic compounds in air and water under UV radiation. On the other hand, the development of visible light activated photocatalysis, for utilizing the available solar energy remains a challenge and requires low band gap materials as sensitizer. Among the various inorganic sensitizers, bulk CdS with an Eg of 2.5 eV and an energetically high-lying conduction band has been identified as a potential candidate. This can be coupled with a large band gap semiconductor (TiO2 with Eg ∼ 3.2 eV) for visible light photocatalysis and solar energy conversion. In the CdS sensitized TiO2 nano-composite system, charge injection from the conduction band of the semiconductor sensitizer to that of TiO2 can lead to an efficient and longer charge separation by minimizing electron-hole recombination. In the present paper, we have carried out a systematic synthesis of nano-structured CdS/TiO2 via reverse micelle process. The structural and microstructural characterizations of the as-prepared CdS/TiO2 nano-composites are determined using XRD and SEM-EDS techniques. The visible light assisted photocatalytic performance is monitored by means of degradation of phenol in water.
Nanocomposite heterogeneous semiconductors with suitable energy levels (gaps) are exhibiting excellent photocatalytic properties under visible light irradiation. TiO 2 /ZnFe 2 O 4 has been selected among different alloys because of (i) its low band gap ~1.9 eV (ii) the nontoxicity of ZnFe 2 O 4 (iii) visible light absorption characteristics of ZnFe 2 O 4 due to its narrow band gap and (iv) not being susceptible to photoanodic corrosion. A mechanochemical synthesis approach using high energy milling is employed to prepare TiO 2 /ZnFe 2 O 4 under different experimental parameters and conditions. The effects of ball milling and calcination on the photocatalytic behavior of TiO 2 and TiO 2 /ZnFe 2 O 4 have been determined. The as-milled nanocomposite materials are characterized with PXD, SEM and EDS procedures. The photocatalytic activity of TiO 2 /ZnFe 2 O 4 nanocomposites for the photodegradation of phenol under visible light irradiation has been studied systematically by UV-Vis spectrometer. It is interesting to note a red shift of 0.25 eV in the absorption edge of the ball-milled TiO 2 sample when compared to the non ball milled TiO 2 photocatalyst. 0900-O09-23.1 Mater. Res. Soc. Symp. Proc. Vol. 900E
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