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ABSTRACT: CeO(2)-TiO(2) nanoparticles were prepared by the sol-gel process using 2-hydroxylethylammonium formate as room-temperature ionic liquid and calcined at different temperatures (500-700°C). CeO(2)-TiO(2)-graphene nanocomposites were prepared by hydrothermal reaction of graphene oxide with CeO(2)-TiO(2) nanoparticles in aqueous solution of ethanol. The photocatalysts were characterized by X-ray diffraction, BET surface area, diffuse reflectance spectroscopy, scanning electron microscopy, and Fourier transformed infrared techniques. The results demonstrate that the room-temperature ionic liquid inhibits the anatase-rutile phase transformation. This effect was promoted by addition of CeO(2) to TiO(2). The addition of graphene to CeO(2)-TiO(2) nanoparticles enhances electron transport and therefore impedes the charge recombination of excited TiO(2). The photodegradation results of the pollutants in aqueous medium under UV irradiation revealed that CeO(2)-TiO(2)-graphene nanocomposites exhibit much higher photocatalytic activity than CeO(2)-TiO(2) and pure TiO(2). The photocatalytic activity of CeO(2)-TiO(2)-graphene nanocomposites decreases with additional increasing of the graphene content. Moreover, comparison of the photocatalytic activities of CeO(2)-TiO(2)-graphene with the other CeO(2)-TiO(2)-carbon demonstrates that CeO(2)-TiO(2)-graphene nanocomposites have the highest photocatalytic activity due to their unique structure and electronic properties. Chemical oxygen demand for solutions of the pollutants gave a good idea about mineralization of them.
Journal of hazardous materials 11/2011; 199-200:170-8. · 4.14 Impact Factor
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ABSTRACT: TiO(2) and transition metal (Cr, Mn, Fe, Co, Ni, Cu, and Zn) doped TiO(2) nanoparticles were synthesized by the sol-gel method using 2-hydroxylethylammonium formate as an ionic liquid. All the prepared samples were calcined at 500 degrees C and characterized by X-ray diffraction (XRD), BET surface area determination, energy dispersive X-ray (EDX) analysis, diffuse reflectance spectroscopy (DRS), and Fourier transformed infrared (FT-IR) techniques. The studies revealed that transition metal (TM) doped nanoparticles have smaller crystalline size and higher surface area than pure TiO(2). Dopant ions in the TiO(2) structure caused significant absorption shift into the visible region. The results of photodegradation of Acid Blue92 (AB92) in aqueous medium under UV light showed that photocatalytic activity of TiO(2) nanoparticles was significantly enhanced by the presence of some transition metal ions. Chemical Oxygen Demand (COD) of dye solutions were done at regular intervals gave a good idea about mineralization of dye.
Journal of hazardous materials 09/2009; 172(2-3):1573-8. · 4.14 Impact Factor
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Microelectronics Journal. 01/2008; 39:1499-1503.
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ABSTRACT: Ab initio molecular orbital calculations have been used to investigate the structures and transition states of 1,3-dipolar cycloadditions between benzonitrile oxide with ethylene, acrylonitrile, tetracyanoethylene and cyclopentene. Geometry optimisations and energy calculations were performed with RHF/6-31G*//RHF/6-31G* in each case. Calculation of vibrational frequencies permitted computation of the enthalpies, Gibbs free energies and rate constant of reactions. Cycloadditions of 1,3-dipolar benzonitrile oxide with electron-poor dipolarophiles have higher rates and lower thermodynamic stability than with other dipolarophiles.
Journal of Chemical Research 05/2002; 2002(6):279-281. · 0.04 Impact Factor
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ABSTRACT: The electron transport characteristics of a 1,10-dimethylene-1,10-dicarba-closo-decaborane (10-vertex carborane) single molecular conductor is investigated via the density functional-based non-equilibrium Green's function (DFT-NEGF) method. We consider three configurations for the molecular wire sandwiched between two Au(1 0 0) electrodes: the hollow site, top site and bridge site positions. Our results show that the energetically favorable hollow site configuration has a higher current intensity than the other configurations.The projection of the density of states (PDOS) and the transmission coefficients T(E) of the two-probe system at zero bias are analyzed, and it suggests that the variation of the coupling between the molecule and the electrodes with external bias leads to the higher conductance for the hollow configuration.Furthermore, the transmission coefficients of the hollow system at various external voltage biases are also investigated and it shows that the broadening of the transmission coefficient spectrum with increasing of the external voltage bias indicates a strong coupling between the molecular orbitals in the carborane and the incident states from the electrodes, and thus the current increases with increases of the bias voltage.
Physica E: Low-dimensional Systems and Nanostructures.
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ABSTRACT: We demonstrate theoretically by density functional non-equilibrium Green's function method that a much simplest two-terminal wire can exhibit switching, and we present a realistic theory of its behavior. We consider a C20-bowl molecular wire sandwiched between an Au (1 0 0) substrate and a monatomic Au scanning tunneling microscope (STM) tip. Lateral motion of the tip over the pentagon ring causes it to change from one conformation class to the other and to switch between a strongly and a weakly conducting state. Thus, surprisingly, despite their apparent simplicity, these Au/C20/Au nanowires are shown to be a convenient switch, the simplest two-terminal molecular switches to date. Experiments with a conventional STM are proposed to test these predictions.
Microelectronics Journal.
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ABSTRACT: This article has been retracted at the request of the Editorial Board of Current Applied Physics. Please see Elsevier Policy on Article Withdrawal (http://www.elsevier.com/locate/withdrawalpolicy).Reason: The authors have plagiarized part of a paper that had already appeared in J. Phys. Chem. B, 109 (2005) 3334–3339: “Changes of Coupling between the Electrodes and the Molecule under External Bias Bring Negative Differential Resistance, by Xingqiang Shi, Xiaohong Zheng, Zhenxiang Dai, Yang Wang, and Zhi Zeng”.One of the conditions of submission of a paper for publication is that authors declare explicitly that their work is original and has not appeared in a publication elsewhere. Re-use of any data should be appropriately cited. As such this article represents a severe abuse of the scientific publishing system. The scientific community takes a very strong view on this matter and we apologize to readers of the journal that this was not detected during the submission process.
Current Applied Physics.
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ABSTRACT: TiO2 and transition metal (Cr, Mn, Fe, Co, Ni, Cu, and Zn) doped TiO2 nanoparticles were synthesized by the sol–gel method using 2-hydroxylethylammonium formate as an ionic liquid. All the prepared samples were calcined at 500 °C and characterized by X-ray diffraction (XRD), BET surface area determination, energy dispersive X-ray (EDX) analysis, diffuse reflectance spectroscopy (DRS), and Fourier transformed infrared (FT-IR) techniques. The studies revealed that transition metal (TM) doped nanoparticles have smaller crystalline size and higher surface area than pure TiO2. Dopant ions in the TiO2 structure caused significant absorption shift into the visible region. The results of photodegradation of Acid Blue92 (AB92) in aqueous medium under UV light showed that photocatalytic activity of TiO2 nanoparticles was significantly enhanced by the presence of some transition metal ions. Chemical Oxygen Demand (COD) of dye solutions were done at regular intervals gave a good idea about mineralization of dye.
Journal of Hazardous Materials.
