通过氧化石墨烯(GO)和壳聚糖(Cs)之间的氢键以及静电作用形成GO水凝胶,从而将纳米硅颗粒和碳纳米管(CNT)原位包封于其中,再经冷冻干燥及随后的热处理制得三维硅/碳纳米管/石墨烯(Si-CNT@G)纳米复合材料。采用X射线衍射(XRD)、扫描电子...通过氧化石墨烯(GO)和壳聚糖(Cs)之间的氢键以及静电作用形成GO水凝胶,从而将纳米硅颗粒和碳纳米管(CNT)原位包封于其中,再经冷冻干燥及随后的热处理制得三维硅/碳纳米管/石墨烯(Si-CNT@G)纳米复合材料。采用X射线衍射(XRD)、扫描电子显微镜(SEM)和透射电子显微镜(TEM)、热重分析(TGA)等技术对制得样品的物相、结构和微观形貌等进行了表征。结果表明,所得复合材料在CNT纵横交织的石墨烯网络中,均匀地分布着纳米硅颗粒。当作为锂离子电池的负极材料时,在两种碳介质的协同作用下,有效缓冲硅材料在充放电过程中脱/嵌锂引起的体积变化,缩短了锂离子和电子传输的距离,Si-CNT@G复合材料表现出较好的循环稳定性以及倍率性能。在500 m A·g^-1的充放电电流密度下,经过200圈循环后,其放电比容量仍高达673.7 m Ah·g^-1,容量保持率高达97%;即使将充放电电流密度升至2000 m A·g^-1时,该复合材料仍保持有566.9 m Ah·g^-1的高可逆放电比容量。独特的制备方法和优越的储锂性能,使得Si-CNT@G纳米复合材料成为理想的高性能锂离子电池负极材料的候选.展开更多
纳米硅碳材料主要成分为纳米硅与碳材料,纳米硅具有较小的颗粒尺寸,其储锂容量较高,碳材料具有较高的电子电导,为复合材料提供较好的电子通道;同时将碳与硅材料复合后能缓和硅材料体积形变带来的应力变化;此外,碳作为包覆材料能有效稳...纳米硅碳材料主要成分为纳米硅与碳材料,纳米硅具有较小的颗粒尺寸,其储锂容量较高,碳材料具有较高的电子电导,为复合材料提供较好的电子通道;同时将碳与硅材料复合后能缓和硅材料体积形变带来的应力变化;此外,碳作为包覆材料能有效稳定电极材料与电解液的界面,使SEI膜稳定生长。因此,硅碳复合材料有望替代石墨成为下一代高能量密度锂离子电池负极。本文简要介绍了纳米先导专项硅负极研究团队在纳米硅碳材料方面的研究进展。通过持续的研发与技术更新,目前低容量复合材料（380-450 m A·h/g）的反弹系数、效率、压实密度、加工性能皆不亚于目前商品石墨的水平;在高容量及超高容量材料（500-2000 m A·h/g）方面,通过精细的结构设计,循环性能和倍率性能等得到了较大提升。展开更多
Considerable research efforts have been devoted to developing novel photocatalysts with increased performances by hybridizing inorganic nanomaterials with carbon nanotubes.In this work,one-dimensional coaxial core-she...Considerable research efforts have been devoted to developing novel photocatalysts with increased performances by hybridizing inorganic nanomaterials with carbon nanotubes.In this work,one-dimensional coaxial core-shell carbon nanotubes@SiC nanotubes were successfully synthesized via in situ growth of SiC coatings on carbon nanotubes by a vapor-solid reaction between silicon vapor and carbon nanotubes.High-resolution transmission electron microscope images show that SiC and carbon nanotubes link to form a robust heterojunction with intrinsic atomic contact,which results in efficient separation of the photogenerated electron-hole pairs on SiC and electron transfer from SiC to carbon nanotubes.Compared with those of similar materials such as pure SiC nanocrystals and SiC nanotubes,the metal-free carbon nanotubes@SiC exhibits an enhanced photocatalytic activity for hydrogen evolution,which is attributed to the enhanced light absorption and the efficient interfacial charge transfer/separation brought about by their one-dimensional coaxial nanoheterostructures.Moreover,the photocatalytic stability of the metal-free carbon nanotubes@SiC was tested for over 20 h without any obvious decay.展开更多
In this paper, a Si-doped single-walled carbon nanotube （SWCNT） （7,7） and several perfect armchair SWCNTs are investigated using the classical molecular dynamics simulations method. The inter-atomic short-range in...In this paper, a Si-doped single-walled carbon nanotube （SWCNT） （7,7） and several perfect armchair SWCNTs are investigated using the classical molecular dynamics simulations method. The inter-atomic short-range interaction is represented by empirical Tersoff bond order potential. The computational results show that the axial Young＇s modulus of the perfect SWCNTs are in the range of 1.099 ± 0.005 TPa, which is in good agreement with the existing experimental results. From our simulation, the Si-doping decreases the Young＇s modulus of SWCNT, and with the increased strain levels, the effect of Si-doped layer in enhancing the local stress level increases. The Young＇s modulus of armchair SWCNTs are weakly affected by tube radius.展开更多
Microstructure and tribological properties of copper-based hybrid nanocomposites reinforced with copper coatedmultiwalled carbon nanotubes (MWCNTs) and silicon carbide (SiC) were studied. Carbon nanotube was varied fr...Microstructure and tribological properties of copper-based hybrid nanocomposites reinforced with copper coatedmultiwalled carbon nanotubes (MWCNTs) and silicon carbide (SiC) were studied. Carbon nanotube was varied from 1% to 4% withsilicon carbide content being fixed at 4%. The synthesis of copper hybrid nanocomposites involves ball milling, cold pressing andsintering followed by hot pressing. The developed hybrid nanocomposites were subjected to density, grain size, and hardness tests.The tribological performances of the nanocomposites were assessed by carrying out dry sliding wear tests using pin-on-steel disctribometer at different loads. A significant decrease in grain size was observed for the developed hybrid composites when comparedwith pure copper. An improvement of 80% in the micro-hardness of the hybrid nanocomposite has been recorded for 4% carbonnanotubes reinforced hybrid composites when compared with pure copper. An increase in content of CNTs in the hybridnanocomposites results in lowering of the friction coefficient and wear rates of hybrid nanocomposites.展开更多
The nanocrystalline SiC films were prepared on Si then annealed at 800℃ and 1 000℃ for 30 minutes （111） substrates by rf magnetron sputtering and in a vacuum annealing system. The crystal structure and crystalliza...The nanocrystalline SiC films were prepared on Si then annealed at 800℃ and 1 000℃ for 30 minutes （111） substrates by rf magnetron sputtering and in a vacuum annealing system. The crystal structure and crystallization of as-annealed SiC films were determined by the Fourier transform infrared （FIR） absorption spectra and the X-ray diffraction （XRD） analysis. Measurement of photoluminescence （PL） of the nanocrystalline SiC （nc-SiC） films shows that the blue light with 473 nm and 477 nm wavelengths emitted at room temperature and that the PL peak shifts to shorter wavelength side and the PL intensity becomes stronger as the annealing temperature decreases. The time-resolved spectrum of the PL at 477 nm exhibits a bi-exponential decay process with lifetimes of 600 ps and 5 ns and a characteristic of the direct band gap. The strong blue light emission with short PL lifetimes suggests that the quantum confinement effect of the SiC nanocrystals resulted in the radiative recombination of the direct optical transitions.展开更多
O484.4 97042538氧化镁膜=MgO layer[刊,中]/贾正根(南京电子器件研究所.江苏,南京(210016))//光电子技术.—1996,16(1).—24-29介绍溅射和丝网印刷法制造的MgO膜的特点以及工艺参数对膜特性的影响。图9表4参5(严寒)O484.4 97042539乙...O484.4 97042538氧化镁膜=MgO layer[刊,中]/贾正根(南京电子器件研究所.江苏,南京(210016))//光电子技术.—1996,16(1).—24-29介绍溅射和丝网印刷法制造的MgO膜的特点以及工艺参数对膜特性的影响。图9表4参5(严寒)O484.4 97042539乙烯对纳米硅碳薄膜晶化的影响=Effect of etheneon the crystallzation of nanocrystalline展开更多
Novel composites were synthesized using AEPTES （3-（2-aminoethylamino）propyltriethoxysilane）, which behaves as an excellent dispersant for MWCNTs （multiwall carbon nanotubes） in polymer film matrices. The thickne...Novel composites were synthesized using AEPTES （3-（2-aminoethylamino）propyltriethoxysilane）, which behaves as an excellent dispersant for MWCNTs （multiwall carbon nanotubes） in polymer film matrices. The thickness of the synthesized nanocomposite films ranged from 50 to 70 lam, having well-dispersed MWCNTs. Increasing the AEPTES concentration from 0.0196 to 0.0300 M, increased the amine content and the dispersion of MWCNTs. The film synthesized at 0.0300 M AETPES exhibited the greatest degree of dispersion among the three samples, which is consistent with a self-assembled silane group interacting with the MWCNT surface.展开更多
The speed of frequency response of all published carbon nanotube （CNT） integrated circuits （ICs） is far from that predicted. The transient response of CNT ICs is explored systematically through the combination of ...The speed of frequency response of all published carbon nanotube （CNT） integrated circuits （ICs） is far from that predicted. The transient response of CNT ICs is explored systematically through the combination of experimental and simulation methods. Complementary field-effect-transistor （FET） based inverters were fabricated on a single semiconducting CNT, and the dynamic response measurement indicates that it can only work at an unexpectedly low speed, i.e. with a large propagation delay of 30 }_ts. Owing to the larger output resistance of CNT FETs, the existence of parasitic capacitances should induce much larger resistive-capacitive （RC） delay than that in Si ICs. Through detailed analysis combining simulation and experimental measurements, several kinds of parasitic capacitances dragging down the actual speed of CNT FET ICs are identified one by one, and each of them limits the speed at different levels through RC delay. It is found that the parasitic capacitance from the measurement system is the dominant one, and the large RC delay lowers the speed of CNT FETs logic circuits to only several kHz which is similar to the experimental results. Various optimized schemes are suggested and demonstrated to minimize the effect of parasitic capacitances, and thus improve the speed of CNT ICs.展开更多
文摘通过氧化石墨烯(GO)和壳聚糖(Cs)之间的氢键以及静电作用形成GO水凝胶,从而将纳米硅颗粒和碳纳米管(CNT)原位包封于其中,再经冷冻干燥及随后的热处理制得三维硅/碳纳米管/石墨烯(Si-CNT@G)纳米复合材料。采用X射线衍射(XRD)、扫描电子显微镜(SEM)和透射电子显微镜(TEM)、热重分析(TGA)等技术对制得样品的物相、结构和微观形貌等进行了表征。结果表明,所得复合材料在CNT纵横交织的石墨烯网络中,均匀地分布着纳米硅颗粒。当作为锂离子电池的负极材料时,在两种碳介质的协同作用下,有效缓冲硅材料在充放电过程中脱/嵌锂引起的体积变化,缩短了锂离子和电子传输的距离,Si-CNT@G复合材料表现出较好的循环稳定性以及倍率性能。在500 m A·g^-1的充放电电流密度下,经过200圈循环后,其放电比容量仍高达673.7 m Ah·g^-1,容量保持率高达97%;即使将充放电电流密度升至2000 m A·g^-1时,该复合材料仍保持有566.9 m Ah·g^-1的高可逆放电比容量。独特的制备方法和优越的储锂性能,使得Si-CNT@G纳米复合材料成为理想的高性能锂离子电池负极材料的候选.
文摘纳米硅碳材料主要成分为纳米硅与碳材料,纳米硅具有较小的颗粒尺寸,其储锂容量较高,碳材料具有较高的电子电导,为复合材料提供较好的电子通道;同时将碳与硅材料复合后能缓和硅材料体积形变带来的应力变化;此外,碳作为包覆材料能有效稳定电极材料与电解液的界面,使SEI膜稳定生长。因此,硅碳复合材料有望替代石墨成为下一代高能量密度锂离子电池负极。本文简要介绍了纳米先导专项硅负极研究团队在纳米硅碳材料方面的研究进展。通过持续的研发与技术更新,目前低容量复合材料（380-450 m A·h/g）的反弹系数、效率、压实密度、加工性能皆不亚于目前商品石墨的水平;在高容量及超高容量材料（500-2000 m A·h/g）方面,通过精细的结构设计,循环性能和倍率性能等得到了较大提升。
基金supported by the National Natural Science Foundation of China(21673083,21802046)the Guangdong Provincial Science and Technology Project(2017A030313090,2014A030310427)~~
文摘Considerable research efforts have been devoted to developing novel photocatalysts with increased performances by hybridizing inorganic nanomaterials with carbon nanotubes.In this work,one-dimensional coaxial core-shell carbon nanotubes@SiC nanotubes were successfully synthesized via in situ growth of SiC coatings on carbon nanotubes by a vapor-solid reaction between silicon vapor and carbon nanotubes.High-resolution transmission electron microscope images show that SiC and carbon nanotubes link to form a robust heterojunction with intrinsic atomic contact,which results in efficient separation of the photogenerated electron-hole pairs on SiC and electron transfer from SiC to carbon nanotubes.Compared with those of similar materials such as pure SiC nanocrystals and SiC nanotubes,the metal-free carbon nanotubes@SiC exhibits an enhanced photocatalytic activity for hydrogen evolution,which is attributed to the enhanced light absorption and the efficient interfacial charge transfer/separation brought about by their one-dimensional coaxial nanoheterostructures.Moreover,the photocatalytic stability of the metal-free carbon nanotubes@SiC was tested for over 20 h without any obvious decay.
文摘In this paper, a Si-doped single-walled carbon nanotube （SWCNT） （7,7） and several perfect armchair SWCNTs are investigated using the classical molecular dynamics simulations method. The inter-atomic short-range interaction is represented by empirical Tersoff bond order potential. The computational results show that the axial Young＇s modulus of the perfect SWCNTs are in the range of 1.099 ± 0.005 TPa, which is in good agreement with the existing experimental results. From our simulation, the Si-doping decreases the Young＇s modulus of SWCNT, and with the increased strain levels, the effect of Si-doped layer in enhancing the local stress level increases. The Young＇s modulus of armchair SWCNTs are weakly affected by tube radius.
文摘Microstructure and tribological properties of copper-based hybrid nanocomposites reinforced with copper coatedmultiwalled carbon nanotubes (MWCNTs) and silicon carbide (SiC) were studied. Carbon nanotube was varied from 1% to 4% withsilicon carbide content being fixed at 4%. The synthesis of copper hybrid nanocomposites involves ball milling, cold pressing andsintering followed by hot pressing. The developed hybrid nanocomposites were subjected to density, grain size, and hardness tests.The tribological performances of the nanocomposites were assessed by carrying out dry sliding wear tests using pin-on-steel disctribometer at different loads. A significant decrease in grain size was observed for the developed hybrid composites when comparedwith pure copper. An improvement of 80% in the micro-hardness of the hybrid nanocomposite has been recorded for 4% carbonnanotubes reinforced hybrid composites when compared with pure copper. An increase in content of CNTs in the hybridnanocomposites results in lowering of the friction coefficient and wear rates of hybrid nanocomposites.
基金The project supported by the National Natural Science Founda-tion of China(Grant No.60476003)
文摘The nanocrystalline SiC films were prepared on Si then annealed at 800℃ and 1 000℃ for 30 minutes （111） substrates by rf magnetron sputtering and in a vacuum annealing system. The crystal structure and crystallization of as-annealed SiC films were determined by the Fourier transform infrared （FIR） absorption spectra and the X-ray diffraction （XRD） analysis. Measurement of photoluminescence （PL） of the nanocrystalline SiC （nc-SiC） films shows that the blue light with 473 nm and 477 nm wavelengths emitted at room temperature and that the PL peak shifts to shorter wavelength side and the PL intensity becomes stronger as the annealing temperature decreases. The time-resolved spectrum of the PL at 477 nm exhibits a bi-exponential decay process with lifetimes of 600 ps and 5 ns and a characteristic of the direct band gap. The strong blue light emission with short PL lifetimes suggests that the quantum confinement effect of the SiC nanocrystals resulted in the radiative recombination of the direct optical transitions.
文摘O484.4 97042538氧化镁膜=MgO layer[刊,中]/贾正根(南京电子器件研究所.江苏,南京(210016))//光电子技术.—1996,16(1).—24-29介绍溅射和丝网印刷法制造的MgO膜的特点以及工艺参数对膜特性的影响。图9表4参5(严寒)O484.4 97042539乙烯对纳米硅碳薄膜晶化的影响=Effect of etheneon the crystallzation of nanocrystalline
文摘Novel composites were synthesized using AEPTES （3-（2-aminoethylamino）propyltriethoxysilane）, which behaves as an excellent dispersant for MWCNTs （multiwall carbon nanotubes） in polymer film matrices. The thickness of the synthesized nanocomposite films ranged from 50 to 70 lam, having well-dispersed MWCNTs. Increasing the AEPTES concentration from 0.0196 to 0.0300 M, increased the amine content and the dispersion of MWCNTs. The film synthesized at 0.0300 M AETPES exhibited the greatest degree of dispersion among the three samples, which is consistent with a self-assembled silane group interacting with the MWCNT surface.
基金This work was supported by the National Basic Research Program of China （Nos. 2011CB933001 and 2011CB933002）, the National Natural Science Foundation of China （Nos. 61322105, 61271051, 61376126, 61321001 and 61390504）, and the Beijing Municipal Science and Technology Commission （Nos. Z131100003213021 and 20121000102）.
文摘The speed of frequency response of all published carbon nanotube （CNT） integrated circuits （ICs） is far from that predicted. The transient response of CNT ICs is explored systematically through the combination of experimental and simulation methods. Complementary field-effect-transistor （FET） based inverters were fabricated on a single semiconducting CNT, and the dynamic response measurement indicates that it can only work at an unexpectedly low speed, i.e. with a large propagation delay of 30 }_ts. Owing to the larger output resistance of CNT FETs, the existence of parasitic capacitances should induce much larger resistive-capacitive （RC） delay than that in Si ICs. Through detailed analysis combining simulation and experimental measurements, several kinds of parasitic capacitances dragging down the actual speed of CNT FET ICs are identified one by one, and each of them limits the speed at different levels through RC delay. It is found that the parasitic capacitance from the measurement system is the dominant one, and the large RC delay lowers the speed of CNT FETs logic circuits to only several kHz which is similar to the experimental results. Various optimized schemes are suggested and demonstrated to minimize the effect of parasitic capacitances, and thus improve the speed of CNT ICs.
