Along with the popularity of environmental protection concepts, the environmental treatment of water pollution attracts widespread attention, among which, the research on Bi-based semiconductor photocatalytic degradat...Along with the popularity of environmental protection concepts, the environmental treatment of water pollution attracts widespread attention, among which, the research on Bi-based semiconductor photocatalytic degradation technology has made great progress. However, the development of such bismuth-based composites still remains a challenging task due to difficult recovery and low catalytic efficiency. Herein, a novel CC/BiPO4</sub>/Bi2</sub>WO6</sub> composite was successfully synthesized through two-step hydrothermal method using activated flexible carbon cloth as a substrate. The results of the photocatalytic degradation experiments showed that the obtained CC/BiPO<sub>4</sub>/Bi<sub>2</sub>WO<sub>6</sub> composites can degrade 92.1% RhB in 60 min under UV-visible light irradiation, which was much higher than that of unloaded BiPO4</sub> (24.4%) and BiPO4</sub>/Bi2</sub>WO6</sub> (52.9%), exhibiting a better adsorption-photocatalytic degradation performance than BiPO4</sub> and BiPO4</sub>/Bi2</sub>WO6</sub>. Photoluminescence spectra indicated that the improved photocatalytic activity was due to the more effective inhibition of photogenerated carrier complexation. Furthermore, the radical capture experiments confirmed that h<sup>+</sup>, ·OH and O<sub>2</sub>-</sup> were the main active substances in the photocatalytic degradation process of RhB by the CC/BiPO4</sub>/Bi2</sub>WO6</sub> composites. More importantly, the prepared CC/BiPO4</sub>/Bi2</sub>WO6</sub> composite had a simple separation process and good recycling stability, and its photocatalytic degradation efficiency can still reach 53.3% after six cycles of RhB degradation. .展开更多
A series of Ce-promoted Mn-Na2WO4/SiO2 catalysts were prepared by incipient wetness impregnation method, and their catalytic performance for oxidative coupling of methane (OCM) was investigated at atmospheric pressu...A series of Ce-promoted Mn-Na2WO4/SiO2 catalysts were prepared by incipient wetness impregnation method, and their catalytic performance for oxidative coupling of methane (OCM) was investigated at atmospheric pressure in a micro-quartz-tube reactor. The catalysts were characterized by X-ray diffraction (XRD), temperature program reduction (TPR) and BET surface area. Ce promoter increased surface area and Na2WO4 species dispersion, which enriched the amount of the surface species. In addition, Ce promoter increased the Na/W species reduction, but the reduction peak shifted to higher temperature. Stability test of 5wt%Ce catalyst indicated suitable performance and stability. The selectivity and yield of C^2+ hydrocarbons after 50 h operation reached 65.5% and 19.6%, respectively, at 840 ℃ over 5wt%Ce-2wt%Mn5wt%Na2WO4/SiO2 catalyst.展开更多
CdGd2 (WO4)4 -δ single crystal was grown using the Czochralski's method. The crystal structure was tetragonal seheelite with lattice parameters a = b = 0.5203 nm and c = 1. 1359 nm. There were vacancies of (WO4)...CdGd2 (WO4)4 -δ single crystal was grown using the Czochralski's method. The crystal structure was tetragonal seheelite with lattice parameters a = b = 0.5203 nm and c = 1. 1359 nm. There were vacancies of (WO4)^2- , therefore, there were some Gd^2+ ions. Langevin paramagnetism and anisotropy were observed from the δ-T curves at room temperature. The susceptibility X//was 3.5018×10^-3, and X⊥ was 3.4403× 10^-2. The anisotropy was also observed in the electron spin resonance (ESR) experiments. The anisotropic Land6 factors were g//= 2. 1333 and g~ = 2. 8411. The direction of easy magnetization was in the α-b plane. Anisotropic paramagnetic Curie constants C//and C⊥ were not only related to macroscopic a that was observed through the experiment, but were also related to J⊥ and J//, which were the microscopic quantum numbers of the Gd^2+ and Gd^3| ions. Based on the detailed analyses, the proportion of 36.8% of Gd^3+ ions to 63.2% of Gd^2+ ions in the Gd ions of the CdGd2(WO4)4-δ crystal was calculated, and δ was 0.638 in the single crystal.展开更多
文摘Along with the popularity of environmental protection concepts, the environmental treatment of water pollution attracts widespread attention, among which, the research on Bi-based semiconductor photocatalytic degradation technology has made great progress. However, the development of such bismuth-based composites still remains a challenging task due to difficult recovery and low catalytic efficiency. Herein, a novel CC/BiPO4</sub>/Bi2</sub>WO6</sub> composite was successfully synthesized through two-step hydrothermal method using activated flexible carbon cloth as a substrate. The results of the photocatalytic degradation experiments showed that the obtained CC/BiPO<sub>4</sub>/Bi<sub>2</sub>WO<sub>6</sub> composites can degrade 92.1% RhB in 60 min under UV-visible light irradiation, which was much higher than that of unloaded BiPO4</sub> (24.4%) and BiPO4</sub>/Bi2</sub>WO6</sub> (52.9%), exhibiting a better adsorption-photocatalytic degradation performance than BiPO4</sub> and BiPO4</sub>/Bi2</sub>WO6</sub>. Photoluminescence spectra indicated that the improved photocatalytic activity was due to the more effective inhibition of photogenerated carrier complexation. Furthermore, the radical capture experiments confirmed that h<sup>+</sup>, ·OH and O<sub>2</sub>-</sup> were the main active substances in the photocatalytic degradation process of RhB by the CC/BiPO4</sub>/Bi2</sub>WO6</sub> composites. More importantly, the prepared CC/BiPO4</sub>/Bi2</sub>WO6</sub> composite had a simple separation process and good recycling stability, and its photocatalytic degradation efficiency can still reach 53.3% after six cycles of RhB degradation. .
文摘A series of Ce-promoted Mn-Na2WO4/SiO2 catalysts were prepared by incipient wetness impregnation method, and their catalytic performance for oxidative coupling of methane (OCM) was investigated at atmospheric pressure in a micro-quartz-tube reactor. The catalysts were characterized by X-ray diffraction (XRD), temperature program reduction (TPR) and BET surface area. Ce promoter increased surface area and Na2WO4 species dispersion, which enriched the amount of the surface species. In addition, Ce promoter increased the Na/W species reduction, but the reduction peak shifted to higher temperature. Stability test of 5wt%Ce catalyst indicated suitable performance and stability. The selectivity and yield of C^2+ hydrocarbons after 50 h operation reached 65.5% and 19.6%, respectively, at 840 ℃ over 5wt%Ce-2wt%Mn5wt%Na2WO4/SiO2 catalyst.
基金Project supported by the National Natural Science Foundation of China (69977005)
文摘CdGd2 (WO4)4 -δ single crystal was grown using the Czochralski's method. The crystal structure was tetragonal seheelite with lattice parameters a = b = 0.5203 nm and c = 1. 1359 nm. There were vacancies of (WO4)^2- , therefore, there were some Gd^2+ ions. Langevin paramagnetism and anisotropy were observed from the δ-T curves at room temperature. The susceptibility X//was 3.5018×10^-3, and X⊥ was 3.4403× 10^-2. The anisotropy was also observed in the electron spin resonance (ESR) experiments. The anisotropic Land6 factors were g//= 2. 1333 and g~ = 2. 8411. The direction of easy magnetization was in the α-b plane. Anisotropic paramagnetic Curie constants C//and C⊥ were not only related to macroscopic a that was observed through the experiment, but were also related to J⊥ and J//, which were the microscopic quantum numbers of the Gd^2+ and Gd^3| ions. Based on the detailed analyses, the proportion of 36.8% of Gd^3+ ions to 63.2% of Gd^2+ ions in the Gd ions of the CdGd2(WO4)4-δ crystal was calculated, and δ was 0.638 in the single crystal.