Ultrafine cube-shape Ce2Sn2O7 nanoparticles crystallized in pure pyrochlore phase with a size of about 10 nm have been successfully synthesized by a facile hydrothermal method.Conditional experiments have been conduct...Ultrafine cube-shape Ce2Sn2O7 nanoparticles crystallized in pure pyrochlore phase with a size of about 10 nm have been successfully synthesized by a facile hydrothermal method.Conditional experiments have been conducted to optimize the processing parameters including temperature,pH,reaction duration,precipitator types to obtain phase-pure Ce2Sn2O7.The crystal structure,morphology and sizes and specific surface area have been characterized by X-ray diffractometer(XRD),Raman spectrum,transmission electron microscope(TEM),high resolution transmission electron microscope(HRTEM),and Brunauer-Emmett-Teller(BET).The as-synthesized Ce2Sn2O7 ultrafine nanocubes have been evaluated as electrode materials for pseudo-capacitors and lithium ion batteries.When testing as supercapacitors,a high specific capacitance of 222 F/g at 0.1 A/g and a good cycling stability with a capacitance retention of higher than 86%after 5000 cycle have been achieved.When targeted for anode material for lithium ion batteries,the nanocubes deliver a high specific reversible capacity of more than 900 mA·h/g at 0.05C rate.The rate capability and cycling performance is also very promising as compared with the traditional graphite anode.展开更多
Catalysts of oxygen reduction reaction （ORR） play key roles in renewable energy technologies such as metal-air batteries and fuel cells. Despite tremendous ef- forts, highly active catalysts with low cost remain elu...Catalysts of oxygen reduction reaction （ORR） play key roles in renewable energy technologies such as metal-air batteries and fuel cells. Despite tremendous ef- forts, highly active catalysts with low cost remain elusive. This work used metal-organic frameworks to synthesize non-precious bimetallic carbon nanocomposites as efficient ORR catalysts. Although carbon-based Cu and Ni are good candidates, the hybrid nanocomposites take advantage of both metals to improve catalytic activity. The resulting molar ratio of Cu/Ni in the nanocomposites can be finely controlled by tuning the recipe of the precursors. Nanocom- posites with a series of molar ratios were produced, and they exhibited much better ORR catalytic performance than their monometallic counterparts in terms of limited current density, onset potential and half-wave potential. In addition, their extraordinary stability in alkaline is superior to that of commercially-available Pt-based materials, which adds to the appeal of the bimetallic carbon nanocomposites as ORR catalysts. Their improved performance can be attributed to the synergetic effects of Cu and Ni, and the enhancement of the carbon matrix.展开更多
基金Project(JCYJ20170817110251498)supported by the Basic Research Project of the Science and Technology Innovation Commission of Shenzhen,ChinaProject(2016TQ03C919)supported by the Guangdong Special Support for the Science and Technology Leading Young Scientist,ChinaProjects(21603094,21703096)supported by the National Natural Science Foundation of China
文摘Ultrafine cube-shape Ce2Sn2O7 nanoparticles crystallized in pure pyrochlore phase with a size of about 10 nm have been successfully synthesized by a facile hydrothermal method.Conditional experiments have been conducted to optimize the processing parameters including temperature,pH,reaction duration,precipitator types to obtain phase-pure Ce2Sn2O7.The crystal structure,morphology and sizes and specific surface area have been characterized by X-ray diffractometer(XRD),Raman spectrum,transmission electron microscope(TEM),high resolution transmission electron microscope(HRTEM),and Brunauer-Emmett-Teller(BET).The as-synthesized Ce2Sn2O7 ultrafine nanocubes have been evaluated as electrode materials for pseudo-capacitors and lithium ion batteries.When testing as supercapacitors,a high specific capacitance of 222 F/g at 0.1 A/g and a good cycling stability with a capacitance retention of higher than 86%after 5000 cycle have been achieved.When targeted for anode material for lithium ion batteries,the nanocubes deliver a high specific reversible capacity of more than 900 mA·h/g at 0.05C rate.The rate capability and cycling performance is also very promising as compared with the traditional graphite anode.
基金supported by the National Natural Science Foundation of China (21671096 and 21603094)the Natural Science Foundation of Shenzhen (JCYJ20150630145302231 and JCYJ20150331101823677)the Science and Technology Innovation Foundation for the Undergraduates of SUSTech (2014S07, 2016S10 and 2016S20)
文摘Catalysts of oxygen reduction reaction （ORR） play key roles in renewable energy technologies such as metal-air batteries and fuel cells. Despite tremendous ef- forts, highly active catalysts with low cost remain elusive. This work used metal-organic frameworks to synthesize non-precious bimetallic carbon nanocomposites as efficient ORR catalysts. Although carbon-based Cu and Ni are good candidates, the hybrid nanocomposites take advantage of both metals to improve catalytic activity. The resulting molar ratio of Cu/Ni in the nanocomposites can be finely controlled by tuning the recipe of the precursors. Nanocom- posites with a series of molar ratios were produced, and they exhibited much better ORR catalytic performance than their monometallic counterparts in terms of limited current density, onset potential and half-wave potential. In addition, their extraordinary stability in alkaline is superior to that of commercially-available Pt-based materials, which adds to the appeal of the bimetallic carbon nanocomposites as ORR catalysts. Their improved performance can be attributed to the synergetic effects of Cu and Ni, and the enhancement of the carbon matrix.
