Carbon nanostructures of different kinds have been synthesized by chemical vapor deposition. By modifying the deposition temperature, the catalyst material, and the hydrocarbon, nanofibers with herringbone structure, multi-walled nanotubes with tubular structure, and single-walled nanotubes were deposited. The nanostructures were purified with different treatment methods. The carbon nanostructures were characterized using scanning and transmission electron microscopy. The hydrogen storage capability was investigated for all obtained nanostructures. The measurements show that the storage capacity of hydrogen is very limited in all the carbon nanostructures.

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Measurements of the static magnetic susceptibility and of the nuclear magnetic resonance of multiwalled vanadium-oxide nanotubes are reported. In this nanoscale magnet the structural lowdimensionality and mixed valency of vanadium ions yield a complex temperature dependence of the static magnetization and the nuclear relaxation rates. Analysis of the different contributions to the magnetism allows to identify individual interlayer magnetic sites as well as strongly antiferromagnetically coupled vanadium spins (S = 1/2) in the double layers of the nanotube's wall. In particular, the data give strong indications that in the structurally well-defined vanadium-spin chains in the walls, owing to an inhomogeneous charge distribution, antiferromagnetic dimers and trimers occur. Altogether, about 30 % of the vanadium ions are coupled in dimers, exhibiting a spin gap of the order of 700 K, the other ∼ 30 % comprise individual spins and trimers, whereas the remaining ∼ 40 % are nonmagnetic.

Single crystalline ammonium trivanadate NH4V3O8 with variable morphologies, including shuttles, flowers, belts, and plates, was synthesized by the hydrothermal treatment of NH4VO3 with acetic acid. The crystals optimally grow under gentle conditions of 140 °C for 48 h. The resulting NH4V3O8 microcrystals were characterized by means of X-ray diffraction, scanning electron microscopy, infrared and Raman spectroscopy, static magnetization studies, and thermal analysis. The key factors to control the size and morphology of the crystals are the pH value and the vanadium concentration. A tentative microscopic growth mechanism is proposed and it is demonstrated how shape and morphology of the resulting microcrystalline material can be tuned by appropriate synthesis parameters.

Anatase TiO 2 nanotubes were synthesized via the hydrothermal method followed by annealing at 500 °C in argon for 1 h. The phase structure, morphology, and composition were investigated in detail by means of X-ray diffraction, scanning and highresolution transmission electron microscopy, infrared spectroscopy, and thermal analysis. The material consists of nanotubes with diameter of 10−15 nm and lengths of several hundred nanometers. The electrochemical properties were investigated by cyclic voltammetry and galvanostatic cycling. The data imply a first cycle irreversible capacity of 385 mAh/g, and capacities of 307 and 265 mAh/g after the second and 50th cycle, respectively, at C/10. The Coulombic efficiency of about 99% after cycle 50 implies excellent cycling stability. Hence anatase TiO 2 nanotubes evidence great potential for usage in highpower lithium-ion batteries.