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Subject: Nanoscale materials ×

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Now showing 1 - 4 of 4
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    Synthesis of quasi-free-standing bilayer graphene nanoribbons on SiC surfaces
    (London : Nature Publishing Group, 2015) Oliveira, Myriano H., Jr.; Lopes, Joao Marcelo J.; Schumann, Timo; Galves, Lauren A.; Ramsteiner, Manfred; Berlin, Katja; Trampert, Achim; Riechert, Henning
    Scaling graphene down to nanoribbons is a promising route for the implementation of this material into devices. Quantum confinement of charge carriers in such nanostructures, combined with the electric field-induced break of symmetry in AB-stacked bilayer graphene, leads to a band gap wider than that obtained solely by this symmetry breaking. Consequently, the possibility of fabricating AB-stacked bilayer graphene nanoribbons with high precision is very attractive for the purposes of applied and basic science. Here we show a method, which includes a straightforward air annealing, for the preparation of quasi-free-standing AB-bilayer nanoribbons with different widths on SiC(0001). Furthermore, the experiments reveal that the degree of disorder at the edges increases with the width, indicating that the narrower nanoribbons are more ordered in their edge termination. In general, the reported approach is a viable route towards the large-scale fabrication of bilayer graphene nanostructures with tailored dimensions and properties for specific applications.
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    Nitrogen and boron doped carbon layer coated multiwall carbon nanotubes as high performance anode materials for lithium ion batteries
    ([London] : Nature Publishing Group, 2021) Liu, Bo; Sun, Xiaolei; Liao, Zhongquan; Lu, Xueyi; Zhang, Lin; Hao, Guang-Ping
    Lithium ion batteries (LIBs) are at present widely used as energy storage and conversion device in our daily life. However, due to the limited power density, the application of LIBs is still restricted in some areas such as commercial vehicles or heavy-duty trucks. An effective strategy to solve this problem is to increase energy density through the development of battery materials. At the same time, a stable long cycling battery is a great demand of environmental protection and industry. Herein we present our new materials, nitrogen and boron doped carbon layer coated multiwall carbon nanotubes (NBC@MWCNTs), which can be used as anodes for LIBs. The electrochemical results demonstrate that the designed NBC@MWCNTs electrode possesses high stable capacity over an ultra-long cycling lifespan (5000 cycles) and superior rate capability even at very high current density (67.5 A g−1). Such impressive lithium storage properties could be ascribed to the synergistic coupling effect of the distinctive structural features, the reduced diffusion length of lithium ions, more active sites generated by doped atoms for lithium storage, as well as the enhancement of the electrode structural integrity. Taken together, these results indicate that the N, B-doped carbon@MWCNTs materials may have great potential for applications in next-generation high performance rechargeable batteries.
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    Stimulated emission depletion microscopy for imaging of engineered and biological nanostructures
    (Saarbrücken : Leibniz-Institut für Neue Materialien, 2010) Schumann, Christian; Cavelius, Christian; Schübbe, Sabrina; Kraegeloh, Annette
    The investigation of interactions between engineered nanostructures and biological systems is a key component in the assessment of potential environmental and health implications due to the increasing application of nanotechnology. Combining the high specificity of bioconjugate fluorescence labeling techniques with the sub-diffraction resolution of Stimulated Emission Depletion (STED) microscopy and state-of-the-art nonlinear image restoration allows the imaging of these interactions on the length scales demanded by the interaction partners. In this article, we give an overview of the experimental approach and discuss its implications on the biological interpretation of the resulting fluorescence micrographs.
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    In-situ quasi-instantaneous e-beam driven catalyst-free formation of crystalline aluminum borate nanowires
    (London : Nature Publishing Group, 2016) Gonzalez-Martinez, Ignacio G.; Gemming, Thomas; Mendes, Rafael; Bachmatiuk, Alicja; Bezugly, Viktor; Kunstmann, Jens; Eckert, Jürgen; Cuniberti, Gianaurelio; Rümmeli, Mark H.
    The catalyst-assisted nucleation and growth mechanisms for many kinds of nanowires and nanotubes are pretty well understood. At times, though, 1D nanostructures form without a catalyst and the argued growth modes have inconsistencies. One such example is the catalyst-free growth of aluminium borate nanowires. Here we develop an in-situ catalyst-free room temperature growth route for aluminium nanowires using the electron beam in a transmission electron microscope. We provide strong experimental evidence that supports a formation process that can be viewed as a phase transition in which the generation of free-volume induced by the electron beam irradiation enhances the atomic mobility within the precursor material. The enhanced atomic mobility and specific features of the crystal structure of Al5BO9 drive the atomic rearrangement that results in the large scale formation of highly crystalline aluminium borate nanowires. The whole formation process can be completed within fractions of a second. Our developed growth mechanism might also be extended to describe the catalyst-free formation of other nanowires.