The binary composite photo-catalysts CeO2/ZiO2, ZrO2/ZiO2 and the ternary composite photo-catalysts H3PW12040-CeO2/TiO2, H3PW12O40-ZrO2/TiO2 were prepared by sol-gel method. The catalysts were characterized by thermog...The binary composite photo-catalysts CeO2/ZiO2, ZrO2/ZiO2 and the ternary composite photo-catalysts H3PW12040-CeO2/TiO2, H3PW12O40-ZrO2/TiO2 were prepared by sol-gel method. The catalysts were characterized by thermogravimetric-differential thermal analysis （TG-DTA）, scanning electron microscopy （SEM） and X-ray diffraction （XRD）. The photocatalytic elimination of methanol was used as model reaction to evaluate the photocatalytic activity of the composite catalysts under ultraviolet light irradiation. The effects of doped content, activation temperature, time, initial concentration of methanol and gas flow rate on the catalytic activity were investigated. The results showed that after doping a certain amount of CeO2 and ZrO2, crystallization process of TiO2 was restrained, particles of catalysts are smaller and more uniform. Doping ZrO2 not only significantly improved the catalytic activity, but also increased thermal stability. Doping H3PW12O40 alSO enhanced the catalytic activity. The catalytic activities of binary and ternary composite photocatalysts were significantly higher than un-doped TiO2. The dynamics law of photocatalytic reaction over the binary CeO2/TiO2 and ZrO2/TiO2 catalysts has been studied. The activation energy 15.627 and 15.631 kJ/mol and pre-exponential factors 0.5176 and 0.9899 s^-1 over each corresponding catalyst were obtained. This reaction accords to the first order dynamics law.展开更多
Absorption, excitation and emission spectra as well as decay time measurements at 10, 77, and 300 K were perfumed for Gd3Sc2Ga3O12 garnet single-crystal doped with Cr^3＋ and Nd^3＋ ions. Strong reabsorption of Cr3＋ ...Absorption, excitation and emission spectra as well as decay time measurements at 10, 77, and 300 K were perfumed for Gd3Sc2Ga3O12 garnet single-crystal doped with Cr^3＋ and Nd^3＋ ions. Strong reabsorption of Cr3＋ emission by Nd3＋ absorption lines was ob- served. The assignments of f-f and d-d transitions were proposed. The broad emission band of chromium ions is an indication that weak/intermediate crystal field strength is present at the Cr3＋ site.展开更多
基金the Hunan Provin-cial Natural Science Foundationthe Scientific Research Fund of Education Department and the Organic Chemistry Key Subject
文摘The binary composite photo-catalysts CeO2/ZiO2, ZrO2/ZiO2 and the ternary composite photo-catalysts H3PW12040-CeO2/TiO2, H3PW12O40-ZrO2/TiO2 were prepared by sol-gel method. The catalysts were characterized by thermogravimetric-differential thermal analysis （TG-DTA）, scanning electron microscopy （SEM） and X-ray diffraction （XRD）. The photocatalytic elimination of methanol was used as model reaction to evaluate the photocatalytic activity of the composite catalysts under ultraviolet light irradiation. The effects of doped content, activation temperature, time, initial concentration of methanol and gas flow rate on the catalytic activity were investigated. The results showed that after doping a certain amount of CeO2 and ZrO2, crystallization process of TiO2 was restrained, particles of catalysts are smaller and more uniform. Doping ZrO2 not only significantly improved the catalytic activity, but also increased thermal stability. Doping H3PW12O40 alSO enhanced the catalytic activity. The catalytic activities of binary and ternary composite photocatalysts were significantly higher than un-doped TiO2. The dynamics law of photocatalytic reaction over the binary CeO2/TiO2 and ZrO2/TiO2 catalysts has been studied. The activation energy 15.627 and 15.631 kJ/mol and pre-exponential factors 0.5176 and 0.9899 s^-1 over each corresponding catalyst were obtained. This reaction accords to the first order dynamics law.
基金supported by Ministry of Science and Higher Education (N N507 372335)
文摘Absorption, excitation and emission spectra as well as decay time measurements at 10, 77, and 300 K were perfumed for Gd3Sc2Ga3O12 garnet single-crystal doped with Cr^3＋ and Nd^3＋ ions. Strong reabsorption of Cr3＋ emission by Nd3＋ absorption lines was ob- served. The assignments of f-f and d-d transitions were proposed. The broad emission band of chromium ions is an indication that weak/intermediate crystal field strength is present at the Cr3＋ site.
