Pure ZnO and Sn-doped ZnO thin films were successfully prepared by the spray pyrolysis method onto glass substrates. The obtained films were characterized by XRD （X-ray diffraction）, SEM （scanning electron microsc...Pure ZnO and Sn-doped ZnO thin films were successfully prepared by the spray pyrolysis method onto glass substrates. The obtained films were characterized by XRD （X-ray diffraction）, SEM （scanning electron microscopy） and ultraviolet-visible spectroscopy. The XRD results showed that the FWHM of Sn-doped ZnO film increased due to the substitution of Sn for Zn, the tin doping within the film causes the ZnO crystallinity to deteriorate. The grains of the film doped with Sn using dibutyltin diacetate were found to be non-uniform distribution through the sample but those appeared to form ganglia-like hills in the case of pure ZnO film. Furthermore, the Sn-doped ZnO films were tested with respect to the photocatalysis in aqueous solutions of MG （malachite green） upon UV-light illumination and in darkness. It was found that Sn-doped ZnO films prepared under specific conditions showed a lower photocatalytic activity than that of pure ZnO films.展开更多
A photocatalyst Cu-BiVO4 was synthesized by the hydrothermal method and was characterized by XRD, UV-vis DRS, and N2 adsorption-desorption measurement. The catalytic activity of the Cu-BiVO4 samples was studied on des...A photocatalyst Cu-BiVO4 was synthesized by the hydrothermal method and was characterized by XRD, UV-vis DRS, and N2 adsorption-desorption measurement. The catalytic activity of the Cu-BiVO4 samples was studied on desulfurization of thiophene dissolved in n-octane, which was used as a model light oil, via photocatalytic oxidation reaction under illumination by visible light. The catalyst characterization results indicated that the loading of Cu on the catalyst did not change the crystal phase of BiVO4, and the crystallinity of the Cu-BiVO4 sample was found to be better at pH=7. The Cu-BiVO4 samples presented a significant bathochromic shift of the absorption band in the visible region, and the absorption intensity increased for the composite catalyst. The desulfurization experiments showed that the Cu-BiVO4 sample prepared at a pH value of 7 had a better catalytic activity. Under proper operating conditions, the desulfurization rate of the model compound achieved by Cu-BiVO4 sample prepared at pH=7 could reach as high as 90%.展开更多
In this paper, globally-averaged, thermospheric total mass density, derived from the orbits of -5000 objects at 250, 400, and 550 km that were tracked from 1967 to 2006, has been used to quantitatively study the annua...In this paper, globally-averaged, thermospheric total mass density, derived from the orbits of -5000 objects at 250, 400, and 550 km that were tracked from 1967 to 2006, has been used to quantitatively study the annual asymmetry of thermospheric mass density and its mechanism（s）. The results show that thermospheric mass density had a significant annual asymmetry, which changed from year to year. The annual asymmetry at the three altitudes varied synchronously and its absolute value increased with altitudes. The results suggest that there is an annual asymmetry in solar EUV radiation that is caused by the difference in the Sun-Earth distance between the two solstices and the random variation of solar activity within a year. This change in radiation results in an annual change in the thermospheric temperature and thus the scale height of the neutral gas, and is the main cause of the annual asymmetry of thermospheric mass density. The annual asymmetry of mass density increases with altitude because of the accumulating effect of the changes in neutral temperature and scale height in the vertical direction.展开更多
文摘Pure ZnO and Sn-doped ZnO thin films were successfully prepared by the spray pyrolysis method onto glass substrates. The obtained films were characterized by XRD （X-ray diffraction）, SEM （scanning electron microscopy） and ultraviolet-visible spectroscopy. The XRD results showed that the FWHM of Sn-doped ZnO film increased due to the substitution of Sn for Zn, the tin doping within the film causes the ZnO crystallinity to deteriorate. The grains of the film doped with Sn using dibutyltin diacetate were found to be non-uniform distribution through the sample but those appeared to form ganglia-like hills in the case of pure ZnO film. Furthermore, the Sn-doped ZnO films were tested with respect to the photocatalysis in aqueous solutions of MG （malachite green） upon UV-light illumination and in darkness. It was found that Sn-doped ZnO films prepared under specific conditions showed a lower photocatalytic activity than that of pure ZnO films.
基金supported by the National Natural Science Foundation of China (No. 21003103)the Nature Scientific Research Foundation of Shaanxi Provincial Education Office of China (No. 2010JS061)Natural Science Foundation Program of Yan’an University (YD2011-19)
文摘A photocatalyst Cu-BiVO4 was synthesized by the hydrothermal method and was characterized by XRD, UV-vis DRS, and N2 adsorption-desorption measurement. The catalytic activity of the Cu-BiVO4 samples was studied on desulfurization of thiophene dissolved in n-octane, which was used as a model light oil, via photocatalytic oxidation reaction under illumination by visible light. The catalyst characterization results indicated that the loading of Cu on the catalyst did not change the crystal phase of BiVO4, and the crystallinity of the Cu-BiVO4 sample was found to be better at pH=7. The Cu-BiVO4 samples presented a significant bathochromic shift of the absorption band in the visible region, and the absorption intensity increased for the composite catalyst. The desulfurization experiments showed that the Cu-BiVO4 sample prepared at a pH value of 7 had a better catalytic activity. Under proper operating conditions, the desulfurization rate of the model compound achieved by Cu-BiVO4 sample prepared at pH=7 could reach as high as 90%.
基金supported by the Chinese Academy of Sciences(Grant No.KZZD-EW-01-2)the National Natural Science Foundation of China(Grant Nos.41229001,41331069,41174139)+1 种基金the Specialized Research Fund for State Key Laboratoriessupported by the US National Science Foundation
文摘In this paper, globally-averaged, thermospheric total mass density, derived from the orbits of -5000 objects at 250, 400, and 550 km that were tracked from 1967 to 2006, has been used to quantitatively study the annual asymmetry of thermospheric mass density and its mechanism（s）. The results show that thermospheric mass density had a significant annual asymmetry, which changed from year to year. The annual asymmetry at the three altitudes varied synchronously and its absolute value increased with altitudes. The results suggest that there is an annual asymmetry in solar EUV radiation that is caused by the difference in the Sun-Earth distance between the two solstices and the random variation of solar activity within a year. This change in radiation results in an annual change in the thermospheric temperature and thus the scale height of the neutral gas, and is the main cause of the annual asymmetry of thermospheric mass density. The annual asymmetry of mass density increases with altitude because of the accumulating effect of the changes in neutral temperature and scale height in the vertical direction.
