The effect of CO on methanol synthesis from CO2 hydrogenation over Cu-Zn-Al cat-alysts have been investigated by TPSR-MS techniques and evaluated by testing the catalytic per-formance. The results indicated that CO ca...The effect of CO on methanol synthesis from CO2 hydrogenation over Cu-Zn-Al cat-alysts have been investigated by TPSR-MS techniques and evaluated by testing the catalytic per-formance. The results indicated that CO can Occupy part of CO2 adsorption site on the catalystsurface to restrain the reverse water gas shift reaction and promote methanol synthesis in CO2hydrogenation . Therefore it inereases the Inethanol selectivity and yield from CO2 hydrogenation.展开更多
Magnetic composites of carbon nanotubes （CNTs） are synthesized by the in situ catalytic decomposition of benzene at temperatures as low as 400℃ over Fe nanoparticles （mean grain size = 26 nm） produced by sol-gel ...Magnetic composites of carbon nanotubes （CNTs） are synthesized by the in situ catalytic decomposition of benzene at temperatures as low as 400℃ over Fe nanoparticles （mean grain size = 26 nm） produced by sol-gel fabrication and hydrogen reduction. The yield of CNT composite is up to about 3025% in a run of 6 h. FE- SEM and HRTEM investigations reveal that one-dimensional carbon species are produced in a large quantity. A relatively high value of magnetization is observed for the composite due to the encapsulation of ferromagnetic Fe3 C and/or α-Fe. The method is suitable for the mass-production of CNT composites that contain magnetic nanoparticles.展开更多
We survey the magnetocaloric effect in perovskite-type oxides （including doped ABO3-type manganese oxides, A3B2OT-type two-layered perovskite oxides, and A2B＇B＇＇O6-type ordered double-perovskite oxides）. Magnetic...We survey the magnetocaloric effect in perovskite-type oxides （including doped ABO3-type manganese oxides, A3B2OT-type two-layered perovskite oxides, and A2B＇B＇＇O6-type ordered double-perovskite oxides）. Magnetic entropy changes larger than those of gadolinium can be observed in polycrystalline La1-xCaxMnO3 and alkali-metal （Na or K） doped La0.8Ca0.2MnO3 perovskite-type manganese oxides. The large magnetic entropy change produced by an abrupt reduction of magnetization is attributed to the anomalous thermal expansion at the Curie temperature. Considerable mag- netic entropy changes can also be observed in two-layered perovskites Lal.6Cal.4Mn207 and La2.5-xK0.5＋xMn2O7＋6 （0 〈 x 〈 0.5）, and double-perovskite Ba2Fe1＋xMol-xO6 （0 〈 x 〈 0.3） near their respective Curie temperatures. Com- pared with rare earth metals and their alloys, the perovskite-type oxides are lower in cost, and they exhibit higher chemical stability and higher electrical resistivity, which together favor lower eddy-current heating. They are potential magnetic refrigerants at high temperatures, especially near room temperature.展开更多
Novel hollow ZnxCdl xS spheres that are uniform in size are synthesized through the one-step thermal evaporation of a mixture of Zn and CdS powder. From an X-ray diffraction （XRD） study, the hexagonal wurtzite phase...Novel hollow ZnxCdl xS spheres that are uniform in size are synthesized through the one-step thermal evaporation of a mixture of Zn and CdS powder. From an X-ray diffraction （XRD） study, the hexagonal wurtzite phase of ZnxCdl_xS is verified, and the Zn mole fraction （x） is determined to be 0.09. According to the experimental results, we propose a mechanism for the growth of Zn0.09Cd0.91S hollow spheres. The results of the cathodoluminescence investigation indicate uniform Zn, Cd, and S distribution of alloyed Zn0.09Cd0.91S, instead of separate CdS, ZnS, or nanocrystals of a core- shell structure. To the best of our knowledge, the fabrication of ZnxCd1-xS hollow spheres of this kind by one-step thermal evaporation has never been reported. This work would present a new method of growing and applying hollow spheres on Si substrates, and the discovery of the Zn0.09Cd0.91S hollow spheres would make the investigation of ZnxCd1-xS micro/nanostructures more interesting and intriguing.展开更多
文摘The effect of CO on methanol synthesis from CO2 hydrogenation over Cu-Zn-Al cat-alysts have been investigated by TPSR-MS techniques and evaluated by testing the catalytic per-formance. The results indicated that CO can Occupy part of CO2 adsorption site on the catalystsurface to restrain the reverse water gas shift reaction and promote methanol synthesis in CO2hydrogenation . Therefore it inereases the Inethanol selectivity and yield from CO2 hydrogenation.
基金Supported by the National Natural Science Foundation of China under Grant No 10674059, the National High Technology Research and Development Program of China under Grant No 2007AA021805, and the National Basic Research Program of China under Grant No 2005CB623605.
文摘Magnetic composites of carbon nanotubes （CNTs） are synthesized by the in situ catalytic decomposition of benzene at temperatures as low as 400℃ over Fe nanoparticles （mean grain size = 26 nm） produced by sol-gel fabrication and hydrogen reduction. The yield of CNT composite is up to about 3025% in a run of 6 h. FE- SEM and HRTEM investigations reveal that one-dimensional carbon species are produced in a large quantity. A relatively high value of magnetization is observed for the composite due to the encapsulation of ferromagnetic Fe3 C and/or α-Fe. The method is suitable for the mass-production of CNT composites that contain magnetic nanoparticles.
基金Project supported by the National Natural Science Foundation of China (Grant No. 11174132)the National Basic Research Program of China (Grant Nos. 2011CB922102 and 2012CB932304)the Priority Academic Program Development of Jiangsu Higher Education Institutions, China
文摘We survey the magnetocaloric effect in perovskite-type oxides （including doped ABO3-type manganese oxides, A3B2OT-type two-layered perovskite oxides, and A2B＇B＇＇O6-type ordered double-perovskite oxides）. Magnetic entropy changes larger than those of gadolinium can be observed in polycrystalline La1-xCaxMnO3 and alkali-metal （Na or K） doped La0.8Ca0.2MnO3 perovskite-type manganese oxides. The large magnetic entropy change produced by an abrupt reduction of magnetization is attributed to the anomalous thermal expansion at the Curie temperature. Considerable mag- netic entropy changes can also be observed in two-layered perovskites Lal.6Cal.4Mn207 and La2.5-xK0.5＋xMn2O7＋6 （0 〈 x 〈 0.5）, and double-perovskite Ba2Fe1＋xMol-xO6 （0 〈 x 〈 0.3） near their respective Curie temperatures. Com- pared with rare earth metals and their alloys, the perovskite-type oxides are lower in cost, and they exhibit higher chemical stability and higher electrical resistivity, which together favor lower eddy-current heating. They are potential magnetic refrigerants at high temperatures, especially near room temperature.
基金Project supported by the National Natural Science Foundation of China (Grant No.11174132)the National Key Project for Basic Research of China (Grant Nos.2011CB922102 and 2012CB932304)the Science Fund from the National Laboratory of Solid State Microstructures,Nanjing University,China (Grant No.2010ZZ18)
文摘Novel hollow ZnxCdl xS spheres that are uniform in size are synthesized through the one-step thermal evaporation of a mixture of Zn and CdS powder. From an X-ray diffraction （XRD） study, the hexagonal wurtzite phase of ZnxCdl_xS is verified, and the Zn mole fraction （x） is determined to be 0.09. According to the experimental results, we propose a mechanism for the growth of Zn0.09Cd0.91S hollow spheres. The results of the cathodoluminescence investigation indicate uniform Zn, Cd, and S distribution of alloyed Zn0.09Cd0.91S, instead of separate CdS, ZnS, or nanocrystals of a core- shell structure. To the best of our knowledge, the fabrication of ZnxCd1-xS hollow spheres of this kind by one-step thermal evaporation has never been reported. This work would present a new method of growing and applying hollow spheres on Si substrates, and the discovery of the Zn0.09Cd0.91S hollow spheres would make the investigation of ZnxCd1-xS micro/nanostructures more interesting and intriguing.
