Filters

2013 - 20165

More filters

20195
Reset filters

Settings

Author: Rümmeli, Mark H. × DDC: 620 × Has files: Yes × Publisher: London : Nature Publishing Group ×

Search Results

Now showing 1 - 5 of 5
  • Thumbnail Image
    Item
    Two-dimensional membrane as elastic shell with proof on the folds revealed by three-dimensional atomic mapping
    (London : Nature Publishing Group, 2015) Zhao, Jiong; Deng, Qingming; Ly, Thuc Hue; Han, Gang Hee; Sandeep, Gorantla; Rümmeli, Mark H.
    The great application potential for two-dimensional (2D) membranes (MoS2, WSe2, graphene and so on) aroused much effort to understand their fundamental mechanical properties. The out-of-plane bending rigidity is the key factor that controls the membrane morphology under external fields. Herein we provide an easy method to reconstruct the 3D structures of the folded edges of these 2D membranes on the atomic scale, using high-resolution (S)TEM images. After quantitative comparison with continuum mechanics shell model, it is verified that the bending behaviour of the studied 2D materials can be well explained by the linear elastic shell model. And the bending rigidities can thus be derived by fitting with our experimental results. Recall almost only theoretical approaches can access the bending properties of these 2D membranes before, now a new experimental method to measure the bending rigidity of such flexible and atomic thick 2D membranes is proposed.
  • Thumbnail Image
    Item
    Silicon carbide-free graphene growth on silicon for lithium-ion battery with high volumetric energy density
    (London : Nature Publishing Group, 2015) Son, In Hyuk; Park, Jong Hwan; Kwon, Soonchul; Park, Seongyong; Rümmeli, Mark H.; Bachmatiuk, Alicja; Song, Hyun Jae; Ku, Junhwan; Choi, Jang Wook; Choi, Jae-man; Doo, Seok-Gwang; Chang, Hyuk
    Silicon is receiving discernable attention as an active material for next generation lithium-ion battery anodes because of its unparalleled gravimetric capacity. However, the large volume change of silicon over charge–discharge cycles weakens its competitiveness in the volumetric energy density and cycle life. Here we report direct graphene growth over silicon nanoparticles without silicon carbide formation. The graphene layers anchored onto the silicon surface accommodate the volume expansion of silicon via a sliding process between adjacent graphene layers. When paired with a commercial lithium cobalt oxide cathode, the silicon carbide-free graphene coating allows the full cell to reach volumetric energy densities of 972 and 700 Wh l−1 at first and 200th cycle, respectively, 1.8 and 1.5 times higher than those of current commercial lithium-ion batteries. This observation suggests that two-dimensional layered structure of graphene and its silicon carbide-free integration with silicon can serve as a prototype in advancing silicon anodes to commercially viable technology.
  • Thumbnail Image
    Item
    Monitoring microbial metabolites using an inductively coupled resonance circuit
    (London : Nature Publishing Group, 2015) Karnaushenko, Daniil; Baraban, Larysa; Ye, Dan; Uguz, Ilke; Mendes, Rafael G.; Rümmeli, Mark H.; de Visser, J. Arjan G.M.; Schmidt, Oliver G.; Cuniberti, Gianaurelio; Makarov, Denys
    We present a new approach to monitor microbial population dynamics in emulsion droplets via changes in metabolite composition, using an inductively coupled LC resonance circuit. The signal measured by such resonance detector provides information on the magnetic field interaction with the bacterial culture, which is complementary to the information accessible by other detection means, based on electric field interaction, i.e. capacitive or resistive, as well as optical techniques. Several charge-related factors, including pH and ammonia concentrations, were identified as possible contributors to the characteristic of resonance detector profile. The setup enables probing the ionic byproducts of microbial metabolic activity at later stages of cell growth, where conventional optical detection methods have no discriminating power.
  • Thumbnail Image
    Item
    Understanding the catalyst-free transformation of amorphous carbon into graphene by current-induced annealing
    (London : Nature Publishing Group, 2013) Barreiro, Amelia; Börrnert, Felix; Avdoshenko, Stanislav M.; Rellinghaus, Bernd; Cuniberti, Gianaurelio; Rümmeli, Mark H.; Vandersypen, Lieven M.K.
    We shed light on the catalyst-free growth of graphene from amorphous carbon (a–C) by current-induced annealing by witnessing the mechanism both with in-situ transmission electron microscopy and with molecular dynamics simulations. Both in experiment and in simulation, we observe that small a–C clusters on top of a graphene substrate rearrange and crystallize into graphene patches. The process is aided by the high temperatures involved and by the van der Waals interactions with the substrate. Furthermore, in the presence of a–C, graphene can grow from the borders of holes and form a seamless graphene sheet, a novel finding that has not been reported before and that is reproduced by the simulations as well. These findings open up new avenues for bottom-up engineering of graphene-based devices.
  • Thumbnail Image
    Item
    Twinned growth behaviour of two-dimensional materials
    (London : Nature Publishing Group, 2016) Zhang, Tao; Jiang, Bei; Xu, Zhen; Mendes, Rafael G.; Xiao, Yao; Chen, Linfeng; Fang, Liwen; Gemming, Thomas; Chen, Shengli; Rümmeli, Mark H.; Fu, Lei
    Twinned growth behaviour in the rapidly emerging area of two-dimensional nanomaterials still remains unexplored although it could be exploited to fabricate heterostructure and superlattice materials. Here we demonstrate how one can utilize the twinned growth relationship between two two-dimensional materials to construct vertically stacked heterostructures. As a demonstration, we achieve 100% overlap of the two transition metal dichalcogenide layers constituting a ReS2/WS2 vertical heterostructure. Moreover, the crystal size of the stacked structure is an order of magnitude larger than previous reports. Such twinned transition metal dichalcogenides vertical heterostructures exhibit great potential for use in optical, electronic and catalytic applications. The simplicity of the twinned growth can be utilized to expand the fabrication of other heterostructures or two-dimensional material superlattice and this strategy can be considered as an enabling technology for research in the emerging field of two-dimensional van der Waals heterostructures.