Undoped CeO2 and 0.50-5.00 mol% Fe-doped CeO2 nanoparticles were prepared by a homogeneous precipitation combined with homogeneous/impreganation method, and applied as photocatalyst films prepared by a doctor blade technique. The superior photocatalytic performances of the Fe-doped CeO2 films, compared with undoped CeO2 films, was ascribed mainly to a decrease in band gap energy and an increase in specific surface area of the material. The presence of Fe(3+) as found from XPS analysis, may act as electron acceptor and/or hole donor, facilitating longer lived charge carrier separation in Fe-doped CeO2 films as confirmed by photoluminescence spectroscopy. The 1.50 mol% Fe-doped CeO2 film was found to be the optimal iron doping concentration for MO degradation in this study.

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Photocatalytic Degradation of Methyl Orange by CeO2 and Fe–doped CeO2 Films under Visible Light Irradiation

MIn2O4 (M = Ca, Sr, Ba) semiconductors were synthesized by a simple solid-state reaction and characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), and UV−visible spectrometer. The substitution effects of M2+ ion on the structural and photocatalytic properties for methylene blue (MB) dye degradation were first investigated systematically. It was found that when M goes from Ca to Ba, the crystal structure of these materials changed from orthorhombic to monoclinic structure, resulting in a systematic variation of the photophysical and photocatalytic properties of these materials. Among these semiconductors, CaIn2O4 showed the highest activity in a wide wavelength range of visible light up to 580 nm. The representative product of the MB degradation, SO42-, was examined and indicated that MB was partially mineralized on MIn2O4 (M = Ca, Sr, Ba). The pH value of MB solution and the synthesized temperature of the photocatalyst were also found to have a significant effect on the photocataly...

Effects of substituting Sr2+ and Ba2+ for Ca2+ on the structural properties and photocatalytic behaviors of CaIn2O4

The innovative core-ring structured NiCo2O4 nanoplatelets were found to be novel and promising photocatalysts. The physical and photophysical properties of the photocatalyst were characterized by SEM, TEM, XPS, UV−vis absorption, and photoluminescence, respectively. The core-ring NiCo2O4 nanoplatelets were composed of much smaller nanocrystallines, with an average size of 80−150 nm, compared to the ordinary NiCo2O4 prepared through a conventional hydroxide decomposition method. Moreover, the optical band gap energies of the core-ring NiCo2O4 nanoplatelets were estimated to be 2.06 and 3.63 eV from the UV−vis absorption spectra. The core-ring structured NiCo2O4 photocatalyst exhibited a much higher photocatalytic activity for the degradation of methylene blue than the ordinary NiCo2O4 and TiO2 under visible light irradiation (>420 nm). This enhanced photocatalytic activity of the core-ring NiCo2O4 nanoplatelets was attributed to their higher optical absorption ability, smaller particle size, and more activ...

Photophysical and Photocatalytic Properties of Core-Ring Structured NiCo2O4 Nanoplatelets

A series of novel metal-oxide-supported CeO(2) catalysts were prepared via the wet impregnation method, and their NH(3)-SCR activities were investigated. The Ce/TiO(2)-SiO(2) catalyst with a Ti/Si mass ratio of 3/1 exhibited superior NH(3)-SCR activity and high N(2) selectivity in the temperature range of 250-450 °C. The characterization results revealed that the activity enhancement was correlated with the properties of the support material. Cerium was highly dispersed on the TiO(2)-SiO(2) binary metal oxide support, and the interaction of Ti and Si resulted in greater conversion of Ce(4+) to Ce(3+) on the surface of the catalyst compared to that on the single metal oxide supports. As a result of in the increased number of acid sites on Ce/TiO(2)-SiO(2) that resulted from the addition of SiO(2), the NH(3) adsorption capacity was significantly improved. All of these factors played significant roles in the high SCR activity. More importantly, Ce/TiO(2)-SiO(2) exhibited strong resistance to SO(2) and H(2)O poisoning. After the addition of SiO(2), the number of Lewis-acid sites was not decreased, but the number of Bronsted-acid sites on the TiO(2)-SiO(2) carrier was increased. The introduction of SiO(2) further weakened the alkalinity over the surface of the Ce/TiO(2)-SiO(2) catalyst, which resulted in sulfate not easily accumulating on the surface of the Ce/TiO(2)-SiO(2) catalyst in comparison with Ce/TiO(2).

A.A. Belhekar

Papers

Photocatalytic activity of titania modified mesoporous silica for pollution control

Effect of acid sites of Al- and Fe-Ferrierite on m-xylene isomerization