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Facile Synthesis of Coaxial CNTs/MnOx-Carbon Hybrid Nanofibers and Their Greatly Enhanced Lithium Storage Performance.

Yang Z, Lv J, Pang H, Yan W, Qian K, Guo T, Guo Z - Sci Rep (2015)

Bottom Line: Carbon nanotubes (CNTs)/MnOx-Carbon hybrid nanofibers have been successfully synthesized by the combination of a liquid chemical redox reaction (LCRR) and a subsequent carbonization heat treatment.The nanostructures exhibit a unique one-dimensional core/shell architecture, with one-dimensional CNTs encapsulated inside and a MnOx-carbon composite nanoparticle layer on the outside.The particular porous characteristics with many meso/micro holes/pores, the highly conductive one-dimensional CNT core, as well as the encapsulating carbon matrix on the outside of the MnOx nanoparticles, lead to excellent electrochemical performance of the electrode.

View Article: PubMed Central - PubMed

Affiliation: National &Local United Engineering Laboratory of Flat Panel Display Technology, Fuzhou University, Fuzhou 350002, P. R. China.

ABSTRACT
Carbon nanotubes (CNTs)/MnOx-Carbon hybrid nanofibers have been successfully synthesized by the combination of a liquid chemical redox reaction (LCRR) and a subsequent carbonization heat treatment. The nanostructures exhibit a unique one-dimensional core/shell architecture, with one-dimensional CNTs encapsulated inside and a MnOx-carbon composite nanoparticle layer on the outside. The particular porous characteristics with many meso/micro holes/pores, the highly conductive one-dimensional CNT core, as well as the encapsulating carbon matrix on the outside of the MnOx nanoparticles, lead to excellent electrochemical performance of the electrode. The CNTs/MnOx-Carbon hybrid nanofibers exhibit a high initial reversible capacity of 762.9 mAhg(-1), a high reversible specific capacity of 560.5 mAhg(-1) after 100 cycles, and excellent cycling stability and rate capability, with specific capacity of 396.2 mAhg(-1) when cycled at the current density of 1000 mAg(-1), indicating that the CNTs/MnOx-Carbon hybrid nanofibers are a promising anode candidate for Li-ion batteries.

No MeSH data available.


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(a) Low-magnification TEM image of CNTs/MnOx hybrid nanofibers, (b) HRTEM image and SAED pattern (inset) of a section of CNTs/MnOx hybrid nanofiber; (c) low-magnification TEM image of CNTs/MnOx-Carbon hybrid nanofibers, (d) HRTEM image and SAED pattern (inset) of a section of CNTs/MnOx-Carbon hybrid nanofiber.
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f3: (a) Low-magnification TEM image of CNTs/MnOx hybrid nanofibers, (b) HRTEM image and SAED pattern (inset) of a section of CNTs/MnOx hybrid nanofiber; (c) low-magnification TEM image of CNTs/MnOx-Carbon hybrid nanofibers, (d) HRTEM image and SAED pattern (inset) of a section of CNTs/MnOx-Carbon hybrid nanofiber.

Mentions: Transmission electron microscopy (TEM) of the as-synthesized MnO2 powders, and the CNTs/MnOx and CNTs/MnOx-Carbon hybrid nanofibers has shed further light on their structural and morphological characteristics (see Fig. 3 and Supporting Information Fig. S4). As shown in Fig. 3(a), many tiny MnOx nanoparticles with diameters of ~5 nm, inherited from the tiny nature of the MnO2 nanoparticle precursor (see Fig. S4), are uniformly and tightly loaded on the surfaces of the CNTs to form a core/shell architecture, which is in good accordance with the FE-SEM results (see Fig. 2(c)). As illustrated in Fig. 3(b), the high resolution transmission electron microscope (HRTEM) image of the CNTs/MnOx nanofibers, as well as the corresponding selected area electronic diffraction (SAED) pattern (see Fig. 3(b) inset), reveals that the loading of the manganese oxide particles on the outside of the CNTs, consisting of many manganese oxide nanocrystals, ~5 nm in diameter, is probably attributable to their polycrystalline nature. In Fig. 3(c,d), in the case of the CNTs/MnOx-Carbon hybrid nanofibers, there is an obvious amorphous carbon layer coated on the outside of the MnOx nanoparticles, with thickness of 1–2 nm. As shown in Fig. 3(d), the high resolution transmission electron microscope (HRTEM) image and selected area electronic diffraction (SAED) pattern of the CNTs/MnOx-Carbon hybrid nanofibers further demonstrate that the MnOx in the CNTs/MnOx-Carbon hybrid nanofibers also consists of many nanoparticles/nanocrystals that are uniformly and tightly aligned on the surfaces of the CNTs to form a one-dimensional core/shell morphology, except that both the MnOx nanocrystals and the amorphous carbon form the shell layer in the CNTs/MnOx-Carbon hybrid nanofibers. The SAED patterns of the CNTs/MnOx and CNTs/MnOx-Carbon hybrid nanofibers are characterized by complex diffraction spots, which indicates that the MnOx in these composites exists in polycrystalline form, owing to the reducing reaction between the MnO2 and the carbon matrix during the carbonization treatment, with the products mainly including Mn3O4, Mn2O3, and MnO nanocrystals (see Fig. 1), respectively, which is similar to what has been reported previously3642. Additionally, the manganese oxide contents in the CNTs/MnOx and CNTs/MnOx-Carbon hybrid nanofibers are ~56.6% and ~47.1%, respectively, according to the TGA results (see Fig. S3).


Facile Synthesis of Coaxial CNTs/MnOx-Carbon Hybrid Nanofibers and Their Greatly Enhanced Lithium Storage Performance.

Yang Z, Lv J, Pang H, Yan W, Qian K, Guo T, Guo Z - Sci Rep (2015)

(a) Low-magnification TEM image of CNTs/MnOx hybrid nanofibers, (b) HRTEM image and SAED pattern (inset) of a section of CNTs/MnOx hybrid nanofiber; (c) low-magnification TEM image of CNTs/MnOx-Carbon hybrid nanofibers, (d) HRTEM image and SAED pattern (inset) of a section of CNTs/MnOx-Carbon hybrid nanofiber.
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f3: (a) Low-magnification TEM image of CNTs/MnOx hybrid nanofibers, (b) HRTEM image and SAED pattern (inset) of a section of CNTs/MnOx hybrid nanofiber; (c) low-magnification TEM image of CNTs/MnOx-Carbon hybrid nanofibers, (d) HRTEM image and SAED pattern (inset) of a section of CNTs/MnOx-Carbon hybrid nanofiber.
Mentions: Transmission electron microscopy (TEM) of the as-synthesized MnO2 powders, and the CNTs/MnOx and CNTs/MnOx-Carbon hybrid nanofibers has shed further light on their structural and morphological characteristics (see Fig. 3 and Supporting Information Fig. S4). As shown in Fig. 3(a), many tiny MnOx nanoparticles with diameters of ~5 nm, inherited from the tiny nature of the MnO2 nanoparticle precursor (see Fig. S4), are uniformly and tightly loaded on the surfaces of the CNTs to form a core/shell architecture, which is in good accordance with the FE-SEM results (see Fig. 2(c)). As illustrated in Fig. 3(b), the high resolution transmission electron microscope (HRTEM) image of the CNTs/MnOx nanofibers, as well as the corresponding selected area electronic diffraction (SAED) pattern (see Fig. 3(b) inset), reveals that the loading of the manganese oxide particles on the outside of the CNTs, consisting of many manganese oxide nanocrystals, ~5 nm in diameter, is probably attributable to their polycrystalline nature. In Fig. 3(c,d), in the case of the CNTs/MnOx-Carbon hybrid nanofibers, there is an obvious amorphous carbon layer coated on the outside of the MnOx nanoparticles, with thickness of 1–2 nm. As shown in Fig. 3(d), the high resolution transmission electron microscope (HRTEM) image and selected area electronic diffraction (SAED) pattern of the CNTs/MnOx-Carbon hybrid nanofibers further demonstrate that the MnOx in the CNTs/MnOx-Carbon hybrid nanofibers also consists of many nanoparticles/nanocrystals that are uniformly and tightly aligned on the surfaces of the CNTs to form a one-dimensional core/shell morphology, except that both the MnOx nanocrystals and the amorphous carbon form the shell layer in the CNTs/MnOx-Carbon hybrid nanofibers. The SAED patterns of the CNTs/MnOx and CNTs/MnOx-Carbon hybrid nanofibers are characterized by complex diffraction spots, which indicates that the MnOx in these composites exists in polycrystalline form, owing to the reducing reaction between the MnO2 and the carbon matrix during the carbonization treatment, with the products mainly including Mn3O4, Mn2O3, and MnO nanocrystals (see Fig. 1), respectively, which is similar to what has been reported previously3642. Additionally, the manganese oxide contents in the CNTs/MnOx and CNTs/MnOx-Carbon hybrid nanofibers are ~56.6% and ~47.1%, respectively, according to the TGA results (see Fig. S3).

Bottom Line: Carbon nanotubes (CNTs)/MnOx-Carbon hybrid nanofibers have been successfully synthesized by the combination of a liquid chemical redox reaction (LCRR) and a subsequent carbonization heat treatment.The nanostructures exhibit a unique one-dimensional core/shell architecture, with one-dimensional CNTs encapsulated inside and a MnOx-carbon composite nanoparticle layer on the outside.The particular porous characteristics with many meso/micro holes/pores, the highly conductive one-dimensional CNT core, as well as the encapsulating carbon matrix on the outside of the MnOx nanoparticles, lead to excellent electrochemical performance of the electrode.

View Article: PubMed Central - PubMed

Affiliation: National &Local United Engineering Laboratory of Flat Panel Display Technology, Fuzhou University, Fuzhou 350002, P. R. China.

ABSTRACT
Carbon nanotubes (CNTs)/MnOx-Carbon hybrid nanofibers have been successfully synthesized by the combination of a liquid chemical redox reaction (LCRR) and a subsequent carbonization heat treatment. The nanostructures exhibit a unique one-dimensional core/shell architecture, with one-dimensional CNTs encapsulated inside and a MnOx-carbon composite nanoparticle layer on the outside. The particular porous characteristics with many meso/micro holes/pores, the highly conductive one-dimensional CNT core, as well as the encapsulating carbon matrix on the outside of the MnOx nanoparticles, lead to excellent electrochemical performance of the electrode. The CNTs/MnOx-Carbon hybrid nanofibers exhibit a high initial reversible capacity of 762.9 mAhg(-1), a high reversible specific capacity of 560.5 mAhg(-1) after 100 cycles, and excellent cycling stability and rate capability, with specific capacity of 396.2 mAhg(-1) when cycled at the current density of 1000 mAg(-1), indicating that the CNTs/MnOx-Carbon hybrid nanofibers are a promising anode candidate for Li-ion batteries.

No MeSH data available.


Related in: MedlinePlus