Nanostructured MnO2/CNT composite was synthesized by a soft template approach in the presence of Pluronic P123 surfactant. The product was characterized by X-ray diffraction, thermogravimetric and differential thermal...Nanostructured MnO2/CNT composite was synthesized by a soft template approach in the presence of Pluronic P123 surfactant. The product was characterized by X-ray diffraction, thermogravimetric and differential thermal analyses, Fourier transformed infrared spectroscopy and high-resolution transmission electron microscopy. The results show that the sample consists of poor crystalline α-MnO2 nanorods with a diameter of about 10 nm and a length of 30-50 nm, which absorb on the carbon nanotubes. The electrochemical properties of the product as cathode material for Li-MnO2 cell are evaluated by galvanostatic charge-discharge and electrochemical impedance spectroscopy （EIS）. Compared with pure MnO2 electrode, the MnO2/CNT composite delivers a much larger initial capacity of 275.3 mA-h/g and better rate and cycling performance.展开更多
A porous coral-structured Si/C composite as an anode material was fabricated by coating Si nanoparticles with a carbon layer from polyvinyl alcohol（PVA）, erosion of hydrofluoric（HF） acid, and secondary coating wit...A porous coral-structured Si/C composite as an anode material was fabricated by coating Si nanoparticles with a carbon layer from polyvinyl alcohol（PVA）, erosion of hydrofluoric（HF） acid, and secondary coating with pitch. Three samples with different pitch contents of 30%, 40% and 50% were synthesized. The composition and morphology of the composites were characterized by X-ray diffractometry（XRD） and scanning electron microscopy（SEM）, respectively, and the properties were tested by electrochemical measurements. The results indicated that the composites showed obviously enhanced electrochemical performance compared with that without secondary carbon coating. The second discharge capacity of the composite was 773 m A·h/g at a current density of 100 m A/g, and still retained 669 m A·h/g after 60 cycles with a small capacity fade of less than 0.23%/cycle, while the content of secondary carbon source of pitch was set at 40%. Therefore, the cycle stability of the composite could be excellently improved by regulating carbon content of secondary coating.展开更多
Four novel pyridimine compounds were prepared. The yield of the intermediates was improved with new method making use of Pd(Ⅱ) catalyst and cuprous acetylide which were proved to be practital in the formation of the ...Four novel pyridimine compounds were prepared. The yield of the intermediates was improved with new method making use of Pd(Ⅱ) catalyst and cuprous acetylide which were proved to be practital in the formation of the acetylide which were proved to be practical in the formation of the acetylides. Their nonlinear optical properties were briefly studied.展开更多
A durability test to determine anti-bombardment sensitivity of multi-RE2O3-Mo secondary emission material was carried out and the variation of maximum secondary emission coefficient （δ）max)) was monitored at regula...A durability test to determine anti-bombardment sensitivity of multi-RE2O3-Mo secondary emission material was carried out and the variation of maximum secondary emission coefficient （δ）max)) was monitored at regular intervals. After the experiment, the cathode was analyzed with SEM, EDS and XRD techniques. The results show that δ)max) of multi-RE2O3-Mo cermets cathode heated to 1 100 ℃ under electron bombardment of 300 W/cm2 reaches the peak of 3.35 at 200 h. After 500 h of bombardment, the maximum secondary-electron-yield curve stabilizes. The δ)max) value of the cathode remains at about 2.5 after 1 000 h and represents a good anti-bombardment property. The high δ)max) value of the cathode is related with formation of an enriched Y2O3 layer on the surface under high temperature and with the amount of La2O3 particles in the shape of nanometer distributed on the surface. Under the experimental conditions, the drop of δ)max) value may be caused by the reduction of La2O3 content and the porous layer resulted from evaporation of MoO2, which is formed when Mo at the surface is oxidized.展开更多
As a new attempt to recycle minute metal scraps, the possibility of manufacturing design materials by semisolid extrusion processing was shown.A design material with an intended shape, such as a character or petal sha...As a new attempt to recycle minute metal scraps, the possibility of manufacturing design materials by semisolid extrusion processing was shown.A design material with an intended shape, such as a character or petal shape, was manufactured using minute metal scraps.Similarly, a design material with an intended color pattern for each metal, such as red copper in a white aluminum matrix, resembling grainlike wood, was manufactured by mixing two or more types of minute metal scrap.In addition, secondary design materials, which have engraved patterns on the surface of the target metal made by an electric discharge machine using the above primary design material as an electrode, were manufactured.展开更多
基金Projects(21071153,20976198)supported by the National Natural Science Foundation of China
文摘Nanostructured MnO2/CNT composite was synthesized by a soft template approach in the presence of Pluronic P123 surfactant. The product was characterized by X-ray diffraction, thermogravimetric and differential thermal analyses, Fourier transformed infrared spectroscopy and high-resolution transmission electron microscopy. The results show that the sample consists of poor crystalline α-MnO2 nanorods with a diameter of about 10 nm and a length of 30-50 nm, which absorb on the carbon nanotubes. The electrochemical properties of the product as cathode material for Li-MnO2 cell are evaluated by galvanostatic charge-discharge and electrochemical impedance spectroscopy （EIS）. Compared with pure MnO2 electrode, the MnO2/CNT composite delivers a much larger initial capacity of 275.3 mA-h/g and better rate and cycling performance.
基金Project(11204090)supported by the National Natural Science Foundation of ChinaProject(2013KJCX0050)supported by the Department of Education of Guangdong Province+6 种基金ChinaProjects(2014B0404040672014A0404010052015A0404040432015A090905003201508030033)supported by the Scientific and Technological Plan of Guangdong Province and Guangzhou CityChina
文摘A porous coral-structured Si/C composite as an anode material was fabricated by coating Si nanoparticles with a carbon layer from polyvinyl alcohol（PVA）, erosion of hydrofluoric（HF） acid, and secondary coating with pitch. Three samples with different pitch contents of 30%, 40% and 50% were synthesized. The composition and morphology of the composites were characterized by X-ray diffractometry（XRD） and scanning electron microscopy（SEM）, respectively, and the properties were tested by electrochemical measurements. The results indicated that the composites showed obviously enhanced electrochemical performance compared with that without secondary carbon coating. The second discharge capacity of the composite was 773 m A·h/g at a current density of 100 m A/g, and still retained 669 m A·h/g after 60 cycles with a small capacity fade of less than 0.23%/cycle, while the content of secondary carbon source of pitch was set at 40%. Therefore, the cycle stability of the composite could be excellently improved by regulating carbon content of secondary coating.
文摘Four novel pyridimine compounds were prepared. The yield of the intermediates was improved with new method making use of Pd(Ⅱ) catalyst and cuprous acetylide which were proved to be practital in the formation of the acetylide which were proved to be practical in the formation of the acetylides. Their nonlinear optical properties were briefly studied.
文摘A durability test to determine anti-bombardment sensitivity of multi-RE2O3-Mo secondary emission material was carried out and the variation of maximum secondary emission coefficient （δ）max)) was monitored at regular intervals. After the experiment, the cathode was analyzed with SEM, EDS and XRD techniques. The results show that δ)max) of multi-RE2O3-Mo cermets cathode heated to 1 100 ℃ under electron bombardment of 300 W/cm2 reaches the peak of 3.35 at 200 h. After 500 h of bombardment, the maximum secondary-electron-yield curve stabilizes. The δ)max) value of the cathode remains at about 2.5 after 1 000 h and represents a good anti-bombardment property. The high δ)max) value of the cathode is related with formation of an enriched Y2O3 layer on the surface under high temperature and with the amount of La2O3 particles in the shape of nanometer distributed on the surface. Under the experimental conditions, the drop of δ)max) value may be caused by the reduction of La2O3 content and the porous layer resulted from evaporation of MoO2, which is formed when Mo at the surface is oxidized.
文摘As a new attempt to recycle minute metal scraps, the possibility of manufacturing design materials by semisolid extrusion processing was shown.A design material with an intended shape, such as a character or petal shape, was manufactured using minute metal scraps.Similarly, a design material with an intended color pattern for each metal, such as red copper in a white aluminum matrix, resembling grainlike wood, was manufactured by mixing two or more types of minute metal scrap.In addition, secondary design materials, which have engraved patterns on the surface of the target metal made by an electric discharge machine using the above primary design material as an electrode, were manufactured.
