Fullerene

About: Fullerene is a research topic. Over the lifetime, 12723 publications have been published within this topic receiving 359173 citations.

Quantum chemical molecular dynamics simulation of single-walled carbon nanotube cap nucleation on an iron particle.

Abstract: The atomic scale details of single-walled carbon nanotube (SWNT) nucleation on metal catalyst particles are elusive to experimental observations. Computer simulation of metal-catalyzed SWNT nucleation is a challenging topic but potentially of great importance to understand the factors affecting SWNT diameters, chirality, and growth efficiency. In this work, we use nonequilibrium density functional tight-binding molecular dynamics simulations and report nucleation of sp(2)-carbon cap structures on an iron particle consisting of 38 atoms. One C(2) molecule was placed every 1.0 ps around an Fe(38) cluster for 30 ps, after which a further 410 ps of annealing simulation without carbon supply was performed. We find that sp(2)-carbon network nucleation and annealing processes occur in three sequential and repetitive stages: (A) polyyne chains on the metal surface react with each other to evolve into a Y-shaped polyyne junction, which preferentially form a five-membered ring as a nucleus; (B) polyyne chains on the first five-membered ring form an additional fused five- or six-membered ring; and (C) pentagon-to-hexagon self-healing rearrangement takes place with the help of short-lived polyyne chains, stabilized by the mobile metal atoms. The observed nucleation process resembles the formation of a fullerene cage. However, the metal particle plays a key role in differentiating the nucleation process from fullerene cage formation, most importantly by keeping the growing cap structure from closing into a fullerene cage and by keeping the carbon edge "alive" for the addition of new carbon material.

The geometry of large fullerene cages: C72 to C102

Abstract: Combining an efficient simulated annealing scheme for generating closed, hollow, spheroidal cage structures with a tight‐binding molecular‐dynamics method for energy optimization, the ground‐state structure of every even‐numbered carbon fullerene from C72 to C102 is determined. As a general trend, most ground‐state structures of the large fullerenes have relatively low symmetries. In many cases, several isomers of a fullerene are found to have competitively low energies, which suggests that a mixture of these isomers can be observed in experimental prepared samples.

Inorganic Nanotubes as Nanoreactors: The First MoS2 Nanopods

Abstract: The discovery of WS2 and MoS2 nanotubes and inorganic fullerene-like nanoparticles (IF), the first closed-cage non-carbon nanoparticles, reported by Tenne and co-workers in 1992 and 1993, shortly proceeded the discovery of carbon fullerenes (C60), [3] nanotubes, and onions. The WS2 and MoS2 nanomaterials have shown important applications as solid lubricants, electron devices, catalysts, super shock absorbers, etc. Particularly in the field of tribology, ultralowfriction properties have been observed. As lubricants, the weak interatomic interactions (van der Waals forces) between the MoS2 or WS2 molecular layers in the form of plate-like crystals allow easy, low-strength shearing in vacuum, but their tribological properties remain poor in the presence of humidity or oxygen, limiting their technological applications. On the contrary, isolated, hollow, IF exhibit ultra-low friction and wear in humidity. The mass production of non-agglomerated IF is therefore an important technological challenge. We report here on the first synthesis of MoS2 nanopods-spherical MoS2 nanoparticles grown in the confined geometry of MoS2 nanotube reactors. The nanotubes serve in two roles: as nanoreactors and afterwards as nanocontainers. Due to very thin walls, which break under short ultra sound agitation, the fullerene-like particles can be released in a control way. This special morphology answers also many current questions regarding safe production, storage and transport of nanoparticles. The ability of carbon nanotubes to encapsulate C60 molecules into their central hollow space, forming nano-peapods, is one of the most fascinating new findings in carbon nanomaterials. With their novel structural and electronic properties, nano-peapods represented a new class of hybrid materials which had no analogue in inorganic materials. The fullerenes in these materials exhibit a strong tendency to coalescence and form chains of closed carbon shells or elongated oblong capsules. Scanning tunnelling spectroscopy reveals that the nanotube’s band gap narrows at the sites where the fullerenes are situated, a property of carbon peapods which could be exploited in electronic devices. Nanowires based on Mo6S2I8 are used as precursor crystals (Fig. 1a). This compound was firstly reported in 1983 by C. Perrin and M. Sergent. Single-crystal X-ray analysis shows the lattice parameters of a hexagonal structure with a space group P63/m to be a = 1.6405 nm and c = 1.1952 nm. The structure of extremely brittle needle-like crystals with a 1:20 aspect ratio grown with the long axis along the c-lattice parameter was found to have a one-dimensional chain-like character with the Mo6 octahedral clusters as a basic unit. We synthesized the Mo6S2I8 nanowires directly from elements at 1320 K. The prolonged reaction time (72 hours) resulted in severalmillimeter-long needles having a diameter from several tens to a few hundred nanometers. The material is rather tough, and the individual needles are not easily broken on handling. Comparative electron diffraction studies of a single nanowire reveal a slight torsional deformation with no influence on the nanowire diameter, but which may cause an enhanced mechanical stability. The electron diffraction pattern (Fig. 1b), corresponding to the structure reported by C. Perrin and M. Sergent, confirms that this rarely-synthesized phase grows also as a nanowire with an aspect ratio of over 1:1000. Mo6S2I8 nanowires have been sulphurized at 1100 K in flowing Ar gas containing 1 % of H2S and 1 % of H2. The total mass of the starting material during the two-hour process decreased by 40 % due to a complete removal of iodine. X-ray powder diffraction and X-ray energy dispersive analysis of the end product reveal the I-free MoS2 compound with some traces of MoO3–x. Transmission electron microscopy (Fig. 2) demonstrates the general encapsulation of MoS2 fullerenes inside the MoS2 nanotubes. The morphology of the nanowires was preserved (Fig. 2a), but slightly modulated in diameter. The nanotube walls are relatively thin, in average of 13 nm ± 5 nm, i.e., from 13 up to 29 molecular layers, and varies slightly from a tube to tube, while some fullerene-like particles exceed several hundred nanometers. As an example, the wall of the nanoC O M M U N IC A TI O N

Synthesis of C60-decorated SWCNTs (C60-d-CNTs) and its TiO2-based nanocomposite with enhanced photocatalytic activity for hydrogen production

Abstract: A novel nanostructured carbon/TiO2 nanocomposite photocatalyst is firstly fabricated via a facile hydrothermal process by using fullerene (C60) decorated single-walled carbon nanotubes (SWCNTs) as carbon source, which is denoted as C60-d-CNTs The obtained nanostructured carbon/TiO2 nanocomposites are characterized by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), UV-vis diffuse reflectance spectra (DRS), Raman spectra, X-ray photoelectron spectroscopy (XPS) and photoluminescence spectra (PL), and then are used as catalysts for photocatalytic hydrogen production It is found that the kinds and contents of various carbon nanostructured materials (such as SWCNTs, C60 and C60-d-CNTs) coupled with TiO2 can significantly enhance the photoactivity for hydrogen production, and the 5 wt% C60-d-CNTs/TiO2 nanocomposite exhibits the best performance Experimental results suggest that the C60-d-CNTs as a novel carbon nanostructured material could be more beneficial for the photogenerated carrier separation than SWCNTs and C60 when these carbon nanostructured materials are coupled with TiO2