Metallic ring-shaped nanotube arrays are proposed and its optical transmission properties are studied by using finite-difference time-domain （FDTD） method. Compared with the transmission spectra of conventional circ...Metallic ring-shaped nanotube arrays are proposed and its optical transmission properties are studied by using finite-difference time-domain （FDTD） method. Compared with the transmission spectra of conventional circular nanotube arrays, two photonic band gaps are emerged in the transmission spectra offing-shaped nanotube arrays, the two band gaps and transmission spectra are adjusted by the length, inner radius, intertube spacing and the dielectric constants of the core and embedding medium, and magnitude modification, redshift and blueshift of the resonance modes are observed. A metallic ring-shaped nanotube arrays for subwavelength band-stop filter in the range of visible light can be achieved. To understand its physical origin, field-interference mechanism was suggested by the field distributions. The proposed nanostructures and results may have great potential applications in subwavelength near-field optics.展开更多
Rechargeable aqueous batteries with high power density and energy density are highly desired for electrochemical energy storage.Despite the recent reports of various cathode materials with ultrahigh pseudocapacitance ...Rechargeable aqueous batteries with high power density and energy density are highly desired for electrochemical energy storage.Despite the recent reports of various cathode materials with ultrahigh pseudocapacitance exceeding3000 F g^(-1)(or 800 mA h g^(-1)),the development of anode materials is relatively insufficient,which limits the whole performance of the devices far from practical applications.Herein,we report the preparation of mesoporous Fe_(3)O_(4)@C nanoarrays as high-performance anode for rechargeable Ni/Fe battery by a self-generated sacrificial template method.Zn O/Fe_(3)O_(4)composite was first synthesized by a co-deposition process,and Zn O was subsequently removed by alkali etching to construct the mesoporous structure.A thin carbon film was introduced onto the surface of the electrode by the carbonization of glucose to increase the structural stability of the electrode.The unique mesoporous nanoarray architecture endows the electrode with larger specific surface area,faster charge/mass transport and higher utilization of Fe_(3)O_(4),which shows an ultrahigh specific capacity (292.4 mA h g^(-1)at a current density of 5 mA cm^(-2)) and superior stability in aqueous electrolyte (capacitance retention of 90.8%after 5000cycles).After assembled with hierarchical mesoporous Ni O nanoarray as a cathode,an optimized rechargeable Ni/Fe battery with double mesoporous nanoarray electrodes was fabricated,which provided high energy/power densities(213.3 W h kg^(-1)at 0.658 kW kg^(-1)and 20.7 kW kg^(-1)at113.9 W h kg^(-1),based on the total mass of the active materials)in the potential window of 1.5 V with excellent cyclability(81.7%retention after 5000 charge/discharge cycles).展开更多
We have theoretically investigated the effect of the dielectric core and the dielectric embedding medium separately on the transmission spectra and plasmonic properties of coupled metallic nanotube arrays.It is found ...We have theoretically investigated the effect of the dielectric core and the dielectric embedding medium separately on the transmission spectra and plasmonic properties of coupled metallic nanotube arrays.It is found that the plasmonic properties of the nanotube arrays are strongly influenced by the presence of the dielectric which induces additional screening charges.We show that instead of one single photonic bandgap for the hollow nanotube arrays placed in air,an additional photonic bandgap arises from the presence of dielectric media in the transmission spectra.Based on the localized nature of the electric field distributions,we also clearly show the presence of the local plasmonic resonant modes that originate from multipolar plasmon polaritons in the cross section of these nanotube arrays,and that a large amount of opposing surface charges are built up in the gap between adjacent nanotubes.展开更多
Previously reported examples of electrochemical pseudocapacitors based on cheap metal oxides have suffered from the need to compromise between specific capacitance, rate capacitance, and reversibility. Here we show th...Previously reported examples of electrochemical pseudocapacitors based on cheap metal oxides have suffered from the need to compromise between specific capacitance, rate capacitance, and reversibility. Here we show that NiO nanorod arrays on Ni foam have a combination of ultrahigh specific capacitance （2018 F/g at 2.27 A/g）, high power density （1536 F/g at 22.7 A/g）, and good cycling stability （only 8% of capacitance was lost in the first 100 cycles with no further change in the subsequent 400 cycles）. This resulted in an improvement in the reversible capacitance record for NiO by 50% or more, reaching 80% of the theoretical value, and demonstrated that a three-dimensional regular porous array structure can afford all of these virtues in a supercapacitor. The excellent performance can be attributed to the slim （〈 20 nm） rod morphology, high crystallinity, regularly aligned array structure and strong bonding of the nanorods to the metallic Ni substrate, as revealed by scanning electron microscopy （SEM）, transmission electron microscopy （TEM） and X-ray diffraction （XRD）.展开更多
基金Projects(11164007,61275174)supported by the National Natural Science Foundation of ChinaProject(20100162110068)supported by the Doctoral Program of Higher Education of China+1 种基金Project(20132BAB212007)supported by the Natural Science Foundation of Jiangxi Province,ChinaProject(GJJ11107)supported by Scientific Foundation of Jiangxi Education Department,China
文摘Metallic ring-shaped nanotube arrays are proposed and its optical transmission properties are studied by using finite-difference time-domain （FDTD） method. Compared with the transmission spectra of conventional circular nanotube arrays, two photonic band gaps are emerged in the transmission spectra offing-shaped nanotube arrays, the two band gaps and transmission spectra are adjusted by the length, inner radius, intertube spacing and the dielectric constants of the core and embedding medium, and magnitude modification, redshift and blueshift of the resonance modes are observed. A metallic ring-shaped nanotube arrays for subwavelength band-stop filter in the range of visible light can be achieved. To understand its physical origin, field-interference mechanism was suggested by the field distributions. The proposed nanostructures and results may have great potential applications in subwavelength near-field optics.
基金financially supported by the National Key Research and Development Program of China (2018YFA0702000)the National Natural Science Foundation of China (NSFC),Beijing Natural Science Foundation (2204089)the Fundamental Research Funds for the Central Universities。
文摘Rechargeable aqueous batteries with high power density and energy density are highly desired for electrochemical energy storage.Despite the recent reports of various cathode materials with ultrahigh pseudocapacitance exceeding3000 F g^(-1)(or 800 mA h g^(-1)),the development of anode materials is relatively insufficient,which limits the whole performance of the devices far from practical applications.Herein,we report the preparation of mesoporous Fe_(3)O_(4)@C nanoarrays as high-performance anode for rechargeable Ni/Fe battery by a self-generated sacrificial template method.Zn O/Fe_(3)O_(4)composite was first synthesized by a co-deposition process,and Zn O was subsequently removed by alkali etching to construct the mesoporous structure.A thin carbon film was introduced onto the surface of the electrode by the carbonization of glucose to increase the structural stability of the electrode.The unique mesoporous nanoarray architecture endows the electrode with larger specific surface area,faster charge/mass transport and higher utilization of Fe_(3)O_(4),which shows an ultrahigh specific capacity (292.4 mA h g^(-1)at a current density of 5 mA cm^(-2)) and superior stability in aqueous electrolyte (capacitance retention of 90.8%after 5000cycles).After assembled with hierarchical mesoporous Ni O nanoarray as a cathode,an optimized rechargeable Ni/Fe battery with double mesoporous nanoarray electrodes was fabricated,which provided high energy/power densities(213.3 W h kg^(-1)at 0.658 kW kg^(-1)and 20.7 kW kg^(-1)at113.9 W h kg^(-1),based on the total mass of the active materials)in the potential window of 1.5 V with excellent cyclability(81.7%retention after 5000 charge/discharge cycles).
基金the Excellent Doctorate Dissertation Foundation of Central South University (Grant No.2008yb039)the Postgraduate Innovative Project of Hunan Province (Grant No.CX2009B029)
文摘We have theoretically investigated the effect of the dielectric core and the dielectric embedding medium separately on the transmission spectra and plasmonic properties of coupled metallic nanotube arrays.It is found that the plasmonic properties of the nanotube arrays are strongly influenced by the presence of the dielectric which induces additional screening charges.We show that instead of one single photonic bandgap for the hollow nanotube arrays placed in air,an additional photonic bandgap arises from the presence of dielectric media in the transmission spectra.Based on the localized nature of the electric field distributions,we also clearly show the presence of the local plasmonic resonant modes that originate from multipolar plasmon polaritons in the cross section of these nanotube arrays,and that a large amount of opposing surface charges are built up in the gap between adjacent nanotubes.
基金Acknowledgements We thank Prof. Feng Wang and Dr. Chang Tan for help with electrochemical capacity testing. We also acknowledge the support of the National Natural Science Foundation of China, the 973 Program （No. 2011CBA00503）, the Foundation for Authors of National Excellent Doctoral Dissertations of China, and Program for New Century Excellent Talents in University.
文摘Previously reported examples of electrochemical pseudocapacitors based on cheap metal oxides have suffered from the need to compromise between specific capacitance, rate capacitance, and reversibility. Here we show that NiO nanorod arrays on Ni foam have a combination of ultrahigh specific capacitance （2018 F/g at 2.27 A/g）, high power density （1536 F/g at 22.7 A/g）, and good cycling stability （only 8% of capacitance was lost in the first 100 cycles with no further change in the subsequent 400 cycles）. This resulted in an improvement in the reversible capacitance record for NiO by 50% or more, reaching 80% of the theoretical value, and demonstrated that a three-dimensional regular porous array structure can afford all of these virtues in a supercapacitor. The excellent performance can be attributed to the slim （〈 20 nm） rod morphology, high crystallinity, regularly aligned array structure and strong bonding of the nanorods to the metallic Ni substrate, as revealed by scanning electron microscopy （SEM）, transmission electron microscopy （TEM） and X-ray diffraction （XRD）.
