428 research outputs found
Tubular Organization of SnO2 Nanocrystallites for Improved Lithium Ion Battery Anode Performace
Porous tin oxide nanotubes were obtained by vacuum infiltration of tin oxide nanoparticles into porous aluminum oxide membranes, followed by calcination. The porous tin oxide nanotube arrays so prepared were characterized by FE-SEM, TEM, HRTEM, and XRD. The nanotubes are open-ended, highly ordered with uniform cross-sections, diameters and wall thickness. The tin oxide nanotubes were evaluated as a substitute anode material for the lithium ion batteries. The tin oxide nanotube anode could be charged and discharged repeatedly, retaining a specific capacity of 525 mAh/g after 80 cycles. This capacity is significantly higher than the theoretical capacity of commercial graphite anode (372 mAh/g) and the cyclability is outstanding for a tin based electrode. The cyclability and capacities of the tin oxide nanotubes were also higher than their building blocks of solid tin oxide nanoparticles. A few factors accounting for the good cycling performance and high capacity of tin oxide nanotubes are suggested.Singapore-MIT Alliance (SMA
Template Synthesis of Tubular Sn-Based Nanostructures for Lithium Ion Storage
We report herewith the preparation of SnO₂ nanotubes with very good shape and size control, and with and without a carbon nanotube overlayer, The SnO₂-core/carbon-shell nanotubes are excellent reversible Li ion storage compounds combining the best features of carbon (cyclability) and SnO₂ (capacity) to deliver a high specific capacity (~540-600 mAh/g) simultaneous with good cyclability (0.0375% capacity loss per cycle).Singapore-MIT Alliance (SMA
Revisiting the as a hadronic molecule and its strong decays
Recently, the Belle collaboration measured the ratios of the branching
fractions of the newly observed excited state. They did not
observe significant signals for the decay, and reported an upper limit for the ratio of the three
body decay to the two body decay mode of . In
this work, we revisit the newly observed from the molecular
perspective where this resonance appears to be a dynamically generated state
with spin-parity from the coupled channels interactions of the and in -wave and in -wave. With
the model parameters for the -wave interaction, we show that the ratio of
these decay fractions reported recently by the Belle collaboration can be
easily accommodated.Comment: Published version. Published in Eur.\ Phys.\ J.\ C {\bf 80}, 361
(2020
Hydrodynamic assembly of two-dimensional layered double hydroxide nanostructures.
Formation mechanisms of two-dimensional nanostructures in wet syntheses are poorly understood. Even more enigmatic is the influence of hydrodynamic forces. Here we use liquid flow cell transmission electron microscopy to show that layered double hydroxide, as a model material, may form via the oriented attachment of hexagonal nanoparticles; under hydrodynamic shear, oriented attachment is accelerated. To hydrodynamically manipulate the kinetics of particle growth and oriented attachment, we develop a microreactor with high and tunable shear rates, enabling control over particle size, crystallinity and aspect ratio. This work offers new insights in the formation of two-dimensional materials, provides a scalable yet precise synthesis method, and proposes new avenues for the rational engineering and scalable production of highly anisotropic nanostructures
Poly[[aqua(μ2-oxalato)(μ2-2-oxidopyridinium-3-carboxylato)dysprosium(III)] monohydrate]
In the title complex, {[Dy(C6H4NO3)(C2O4)(H2O)]·H2O}n, the DyIII ion is coordinated by seven O atoms from two 2-oxidopyridinium-3-carboxylate ligands, two oxalate ligands and one water molecule, displaying a distorted bicapped trigonal-prismatic geometry. The carboxylate groups of the 2-oxidopyridinium-3-carboxylate and oxalate ligands link dysprosium metal centres, forming layers parallel to (100). These layers are further connected by intermolecular O—H⋯O hydrogen-bonding interactions involving the coordinated water molecules, forming a three-dimensional supramolecular network. The uncoordinated water molecule is involved in N—H⋯O and O—H⋯O hydrogen-bonding interactions within the layer
Poly[diaquabis(μ3-1H-benzimidazole-5,6-dicarboxylato-κ4 N 3:O 5,O 5′:O 6)bis(μ2-1H,3H-benzimidazolium-5,6-dicarboxylato-κ3 O 5,O 5′:O 6)digadolinium(III)]
In the title complex, [Gd2(C9H4N2O4)2(C9H5N2O4)2(H2O)2]n, two of the benzimidazole-5,6-dicarboxylate ligands are protonated at the imidazole groups. Each GdIII ion is coordinated by six O atoms and one N atom from five ligands and one water molecule, displaying a distorted bicapped trigonal-prismatic geometry. The GdIII ions are linked by the carboxylate groups and imidazole N atoms, forming a layer parallel to (001). These layers are further connected by O—H⋯O and N—H⋯O hydrogen bonds into a three-dimensional supramolecular network
Poly[diaqua(μ2-oxalato-κ4 O 1,O 2:O 1′,O 2′)(μ2-pyrazine-2-carboxylato-κ4 N 1,O:O,O′)neodymium(III)]
In the title complex, [Nd(C5H3N2O2)(C2O4)(H2O)2]n, the NdIII atom is ten-coordinated by one N atom and three O atoms from two pyrazine-2-carboxylate ligands, four O atoms from two oxalate ligands and two water molecules in a distorted bicapped square-antiprismatic geometry. The two crystallographically independent oxalate ligands, each lying on an inversion center, act as bridging ligands, linking Nd atoms into an extended zigzag chain. Neighboring chains are linked by the pyrazine-2-carboxylate ligands into a two-dimensional layerlike network in the (10) plane. The layers are further connected by O—H⋯O and O—H⋯N hydrogen bonds, forming a three-dimensional supramolecular network
Hemi(4,4′-bipyridinium) hexafluoridophosphate bis(4-aminobenzoic acid) 4,4′-bipyridine monohydrate
In the title compound, 0.5C10H10N2
2+·PF6
−·C10H8N2·2C7H7NO2·H2O, the cation is located on a center of symmetry. The crystal structure is determined by a complex three-dimensional network of intermolecular O—H⋯O, O—H⋯N, N—H⋯N and N—H⋯F hydrogen bonds. π–π stacking interactions between neighboring pyridyl rings are also present; the centroid–centroid distance is 3.643 (5) Å. The hexafluoridophosphate anion is disordered over two positions with site-occupancy factors of ca 0.6 and 0.4
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