Manganese oxide nanoflower/carbon nanotube array (CNTA) composite electrodes with hierarchical porous structure, large surface area, and superior conductivity was controllable prepared by combining electrodeposition technique and a vertically aligned CNTA framework. This binder-free manganese oxide/CNTA electrode presents excellent rate capability (50.8% capacity retention at 77 A/g), high capacitance (199 F/g and 305 F/cm 3 ), and long cycle life (3% capacity loss after 20 000 charge/discharge cycles), with strong promise for high-rate electrochemical capacitive energy storage applications.In development of energy storage devices, nanostructured electrode materials have attracted great interest, as they show not only higher capacities but also better rates than traditional materials. 1-6 Nanostructured electrode materials are key components in the advancement of future energy technologies; thus, strategies for preparing high-performance nanomaterials are required. 5 However, direct synthesis of complex nanostructures still remains a challenge in areas of materials science. 7,8 Nowadays, much research on electrochemical capacitors (ECs) is aimed at increasing power and energy densities as well as lowering fabrication costs while using environmentally friendly materials. Specifically, it was found that RuO 2 exhibits prominent capacitive properties as ECs electrode materials; 9 however, its high cost excludes it from wide application. Relatively low cost materials such as MnO x and NiO x can also be used as electrode materials, but their poor rate capability need to be enhanced. 10,11 Manganese oxides (MO) have been thoroughly investigated because of their importance in industrial applications, such as catalysis and energy storage. [12][13][14][15][16] Over the years various nanostructured manganese oxides, including dendritic clusters, nanocrystals with different shapes, nanowires, nanotubes, nanobelts, and nanoflowers, have been synthesized. [17][18][19][20][21][22][23][24] In order to greatly increase electrochemical performance of manganese oxides, a hierarchical porous structure 25 with high electronic conductivity 26 must be considered. Nevertheless, up to now, no method has been reported to fabricate hierarchical porous and binder-free manganese oxide composite electrodes with superior electronic conductive paths. In this paper, we realized this goal by a combination of a carbon nanotube array (CNTA) framework and an electrodeposition technique to fabricate a composite structure, that is, well-dispersed manganese oxide nanoflowers on a vertically aligned CNTA. CNTA is excellent for electrodepositing transition metal oxides because of its regular pore structure, high surface area, homogeneous property (binderfree), and excellent conductivity. [27][28][29][30] The experimental results show that the manganese oxide/CNTA composite electrode exhibits superior rate performance (50.8% capacitance retention at 77 A/g) in an EC, thus, making it very promising for high-rate electrochemical capacitive energy ...

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Rapid and efficient separation/purification of pure metallofullerenes M(x)@C(n) (M = metal; x = 1, 2; n > 70) and carbide metallofullerenes of the type M(y)C(2)@C(n-2) (y = 2, 3, 4; n - 2 > 68) has been reported. The present method utilizes rapid and almost perfect preferential formation of TiCl(4) (generally known as a Lewis acid)-metallofullerene complexes, which easily decompose to provide pure metallofullerene powders by a simple water treatment. The present method enables one to separate the metallofullerenes up to >99% purity within 10 min without using any type of high-performance liquid chromatography (HPLC). It is found that the oxidation potentials of the metallofullerenes are crucial factors for efficient purification. The current separation/purification technique may open a brand-new era for inducing further applications and commercialization of endohedral metallofullerenes.

Edge structures and atomic defects can significantly affect the physical and chemical properties of low-dimensional materials, such as nanoribbons, and therefore merit a thorough investigation at the atomic scale. Here, we successfully discriminate single atoms on a monolayered tungsten disulphide nanoribbon by means of time-resolved annular dark-field imaging and spatially resolved electron energy-loss spectroscopy. We unambiguously identify and successfully visualize in motion atomic defects, such as vacancies and edge atoms, using scanning transmission electron microscopy. We also report a direct observation of slip deformation in the nanoribbons and present evidence demonstrating that the deformation process involves the migration of vacancies and rearrangement of tungsten atoms. Single-atom defects are successfully observed for the first time during plastic deformation.

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The unstable fullerene I h -C 80 can be stabilized greatly by encapsulation of two rare-earth metal atoms in its interior. Here we present a theoretical study on the electronic structures and stabilities of dimetallofullerene M 2 @I h -C 80 (M = Y, La, Gd, Lu). Density functional calculations demonstrate that La 2 @I h -C 80 has a closed-shell configuration, whereas Y 2 @I h -C 80 has a triplet ground state. Unlike La 2 @I h -C 80 with a high stability, Y 2 @I h -C 80 is found to be a highly reactive radical due to the unpaired electron distributed on the fullerene cage. Such characteristic properties of La 2 @I h -C 80 and Y 2 @I h -C 80 originate from the different energy levels of the metal-based molecular orbitals. Y 2 @I h -C 80 can be stabilized, however, through exterior functionalization with a CF 3 group. Interestingly, metallofullerenes Gd 2 @I h -C 80 and Lu 2 @I h -C 80 have similar frontier molecular orbitals and chemical stabilities to those of Y 2 @I h -C 80 .

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Layered tungsten disulfide nanostructures are of both fundamental and technological interest. The widths of currently synthesized WS 2 ribbons are in the microscale. By using single-walled carbon nanotubes and double-walled carbon nanotubes as templates, we fabricate WS 2 nanoribbons with smooth zigzag edges and uniform widths down to 1-3 nm and layer numbers down to 1-3, dependent on the nanotube diameter. Although bulk WS 2 is a nonmagnetic semiconductor, the ultra-narrow freestanding zigzag-edged WS 2 nanoribbons turn out to be magnetic or nonmagnetic metals depending on the edge passivation way according to our first-principles calculations, whereas the ultra-narrow armchair-edged WS 2 nanoribbons remain nonmagnetic semiconductors with a narrow gap. Results and discussionFormation of WS 2 was confirmed by Raman scattering measurements. Remarkable Raman signals (E 2g 1 mode, 350 cm À1