Fe^3＋ -doped nanometer TiO2 photocatalysts were prepared by sol-gel technique. TiO2 powders with different Fe^3＋ / Ti^4 ＋ molar ratios ranging from 0. 05% to 25% were synthesized by calcinating the gels in the temp...Fe^3＋ -doped nanometer TiO2 photocatalysts were prepared by sol-gel technique. TiO2 powders with different Fe^3＋ / Ti^4 ＋ molar ratios ranging from 0. 05% to 25% were synthesized by calcinating the gels in the temperature range of 200-600 ℃ . The effects of the content of iron ions and calcination temperature on the physical properties of the powders and their photocatalytic activities were examined by the photodecorapositon of methyl orange in sunlight. The results show that Fe dopant can decrease the temperature of nanatase-ratile transformation. The ideal photocatalytic property was achieved when the sample with an Fe^3＋ / Ti^4＋ ratio of 20 at% was calcined at about 300 ℃ for an hour, which is superior to that of commercial Degussa P-25. The optimum microstructure of the Fe-doped TiO2 for a high photocatalytic activity in sunlight is consisted of nanatase and ratile.展开更多
Among the perovskite-type oxides with symmetrical structure applied in oxygen permeable membranes, cubic phase structure is the most favorable for oxygen permeation. In order to stabilize the cubic perovskite structur...Among the perovskite-type oxides with symmetrical structure applied in oxygen permeable membranes, cubic phase structure is the most favorable for oxygen permeation. In order to stabilize the cubic perovskite structure of BaFeO3-δ material at room temperature, iron was partially substituted by praseodymium. BaFe1-yPryO3-δ powders were synthesized by a solid state reaction method, and sintered samples were prepared from the synthesized BaFe1-yPryO3-δ powders. X-ray diffraction results reveal that the BaFe1-yPryO3-δ samples remain cubic structure at praseodymium substitution amount of y 0.05, 0.075, 0.1. Scanning electron microscope observation indicates that the sintered samples contain only a small amount of enclosed pores and the grain size of BaFe1-yPryO3-δ increase monotonically with the increase of the praseodymium doping amount, praseodymium doping promotes the grain size growth. Tests of electrical conductivity and oxygen permeation flux show that praseodymium doping improves the conduction properties of BaFe1-yPryO3-δ and BaFe0.9Pr0.1O3-δ composition has an electrical conductivity of 6.5 S/era and an oxygen permeation of 1.112 mL/（cm^2.min） at 900 ℃, respectively. High temperature XRD in- vestigation shows that the crystal structure of BaFe0.975Pr0.025O3-δ membrane completely transform to cubic phase at 700℃. The present test results have shown that partially substitution of Fe by praseodymium in BaFeO3 can stabilize the cubic structure and improve the properties.展开更多
基金Founded by the Science and Technology Foundation of AnhuiProvince (No.010301E2)
文摘Fe^3＋ -doped nanometer TiO2 photocatalysts were prepared by sol-gel technique. TiO2 powders with different Fe^3＋ / Ti^4 ＋ molar ratios ranging from 0. 05% to 25% were synthesized by calcinating the gels in the temperature range of 200-600 ℃ . The effects of the content of iron ions and calcination temperature on the physical properties of the powders and their photocatalytic activities were examined by the photodecorapositon of methyl orange in sunlight. The results show that Fe dopant can decrease the temperature of nanatase-ratile transformation. The ideal photocatalytic property was achieved when the sample with an Fe^3＋ / Ti^4＋ ratio of 20 at% was calcined at about 300 ℃ for an hour, which is superior to that of commercial Degussa P-25. The optimum microstructure of the Fe-doped TiO2 for a high photocatalytic activity in sunlight is consisted of nanatase and ratile.
基金supported by the National Natural Science Foundation of China(No.216060647)the Industry-University-Research Project of Aviation Industry Corporation of China (No.cxy2012HFGD025)
文摘Among the perovskite-type oxides with symmetrical structure applied in oxygen permeable membranes, cubic phase structure is the most favorable for oxygen permeation. In order to stabilize the cubic perovskite structure of BaFeO3-δ material at room temperature, iron was partially substituted by praseodymium. BaFe1-yPryO3-δ powders were synthesized by a solid state reaction method, and sintered samples were prepared from the synthesized BaFe1-yPryO3-δ powders. X-ray diffraction results reveal that the BaFe1-yPryO3-δ samples remain cubic structure at praseodymium substitution amount of y 0.05, 0.075, 0.1. Scanning electron microscope observation indicates that the sintered samples contain only a small amount of enclosed pores and the grain size of BaFe1-yPryO3-δ increase monotonically with the increase of the praseodymium doping amount, praseodymium doping promotes the grain size growth. Tests of electrical conductivity and oxygen permeation flux show that praseodymium doping improves the conduction properties of BaFe1-yPryO3-δ and BaFe0.9Pr0.1O3-δ composition has an electrical conductivity of 6.5 S/era and an oxygen permeation of 1.112 mL/（cm^2.min） at 900 ℃, respectively. High temperature XRD in- vestigation shows that the crystal structure of BaFe0.975Pr0.025O3-δ membrane completely transform to cubic phase at 700℃. The present test results have shown that partially substitution of Fe by praseodymium in BaFeO3 can stabilize the cubic structure and improve the properties.
