Pseudo-topotactic conversion of carbon nanotubes into one-dimensional carbon nanowires is a challenging but feasible path to obtain desired diameters and morphologies. Here, a previously predicted but experimentally unobserved carbon allotrope, T-carbon, has been produced from pseudo-topotactic conversion of a multi-walled carbon nanotube suspension in methanol by picosecond pulsed-laser irradiation. The as-grown T-carbon nanowires have the same diameter distribution as pristine carbon nanotubes, and have been characterized by high-resolution transmission electron microscopy, fast Fourier transform, electron energy loss, ultraviolet–visible, and photoluminescence spectroscopies to possess a diamond-like lattice, where each carbon is replaced by a carbon tetrahedron, and a lattice constant of 7.80 Å. The change in entropy from carbon nanotubes to T-carbon reveals the phase transformation to be first order in nature. The computed electronic band structures and projected density of states are in good agreement with the optical absorption and photoluminescence spectra of the T-carbon nanowires.

Carbon is a girl′s best friend: Carbon‐based nanowires have been produced during thermal annealing of diamantane‐4,9‐dicarboxylic acid in carbon nanotubes under hydrogen atmosphere (see scheme). HR‐TEM images, Raman spectra, and structural transformations observed under an intense electron beam suggest that the as‐produced carbon‐based nanowires are sp3 diamond nanowires, consistent with our computational results.

We report the assembly and thermal transformation of linear diamondoid assemblies inside carbon nanotubes. Our calculations and observations indicate that these molecules undergo selective reactions within the narrow confining space of a carbon nanotube. Upon vacuum annealing of adamantane molecules encapsulated in a carbon nanotube, we observe a sharp Raman feature at 1857 cm(-1), which we interpret as a stretching mode of carbon chains formed by thermal conversion of adamantane inside a carbon nanotube. Introduction of pure hydrogen during thermal annealing, however, suppresses the formation of carbon chains and seems to keep adamantane intact.

Black phosphorene has attracted much attention as a semiconducting two‐dimensional material. Violet phosphorus is another layered semiconducting phosphorus allotrope with unique electronic and optoelectronic properties. However, no confirmed violet crystals or reliable lattice structure of violet phosphorus had been obtained. Now, violet phosphorus single crystals were produced and the lattice structure has been obtained by single‐crystal x‐ray diffraction to be monoclinic with space group of P2/n (13) (a=9.210, b=9.128, c=21.893 Å, β=97.776°). The lattice structure obtained was confirmed to be reliable and stable. The optical band gap of violet phosphorus is around 1.7 eV, which is slightly larger than the calculated value. The thermal decomposition temperature was 52 °C higher than its black phosphorus counterpart, which was assumed to be the most stable form. Violet phosphorene was easily obtained by both mechanical and solution exfoliation under ambient conditions.

Molybdenum disulfides and carbides are effective catalysts for hydrogenation and hydridesulfurization, where MoS2 nanostructures are also highly promising materials for lithium ion batteries. High surface-to-volume ratio and strong interactions with conducting networks are crucial factors for their activities. A new hybrid structure of multiwalled carbon nanotube (MWCNT) with alternate MoC nanoparticles and MoS2 nanosheets (MoS2 + MoC-MWCNT) has been synthesized by controlled carburization of core-shell MoS2-MWCNT hybrid nanotubes and demonstrated by HRTEM, FFT, XRD, and Raman scattering. The MoS2 nanosheets (∼10 nm) remain tightly connected to MWCNT surfaces with {001} planes in parallel to MWCNT walls and the highly crystallized α-MoC particles (∼10 nm) are adhered to MWCNTs at angles of 60-80° between {111} planes and MWCNT walls. The electrochemical performances of the hybrid structures have been demonstrated as anodes for lithium ion batteries to be significantly increased by breaking MoS2 nanotubes into nanosheets (patches) on MWCNT surfaces, especially at high current rates. The specific capacities of MoS2 + MoC-MWCNT sample with ∼23% MoS2 have been demonstrated to be higher than those of MoS2-MWCNTs containing ∼70% MoS2.

In contrast to the extensively studied empty C 60 and C 70 fullerenes, the extraction of the corresponding endohedral metallofullerenes M@C 60 and M@C 70 (e.g., M = Sc, Y, La, Ce, or Gd) (Figure 1 a) has been a long-standing challenge ever since the experimental discovery in 1985 [1] and the first macroscopic production in 1991 [2] of metallofullerenes. It has been well-known [3] that M@C 60 and M@C 70 are insoluble in common fullerene solvents such as toluene and carbon disulfide, although the yields of M@C 60 and M@C 70 in raw soot are fairly high according to mass spectrometric analysis. Besides M@C 60 and M@C 70 , there are a large number of other insoluble, the so-called small-bandgap (or small HOMO-LUMO gap) metallofullerenes such as M@C 72 and M@C 74 . These metallofullerenes are highly reactive because of their open-shell electronic configurations or small bandgaps, and they tend to form insoluble polymerized solids in raw soot. [4] The highly reactive small-bandgap metallofullerenes can be stabilized either by electrochemical reduction or chemical functionalization. Diener and Alford reported that insoluble polymerized Gd metallofullerenes can be reduced into soluble closed-shell anions by an electrochemical method. [4] Exohedral derivatization is another way to stabilize smallbandgap fullerenes and metallofullerenes. For example, C 74 can be extracted through exohedral fluorination or trifluoromethylation. [5] Similarly, insoluble metallofullerenes La@C 2n (2n = 72, 74, and 80) become soluble in organic solvents after functionalization with dichlorophenyl groups. [6] However, the most interesting La@C 60 and La@C 70 fullerenes are still unavailable.Arc discharge is the most commonly used technique for the production of metallofullerenes, which is typically performed with a metal/graphite composite rod in a helium atmosphere. [3a, 7] It is convenient to introduce additional gaseous or solid reagents into the arc-discharge chamber to produce new types of fullerenes or metallofullerenes. [8] For instance, trifluoromethyl derivatives of C 60 were produced using polytetrafluoroethene (PTFE) as a source for functional groups during arc discharge. [8e] Here we demonstrate an arcdischarge method for producing derivatives of small-bandgap metallofullerenes using PTFE. As shown schematically in Figure 1 b, PTFE is placed near the area where arc discharge occurs. Because of the high-temperature of the arc zone, PTFE is evaporated together with the metal/graphite rod during arc discharge. As a consequence, a series of trifluoromethyl derivatives of insoluble metallofullerenes M@C 2n -(CF 3 ) m (e.g., 2n = 60, 70, 72, or 74) are formed effectively. Surprisingly, these derivatives, including those of M@C 60 and M@C 70 , are totally soluble and stable in such organic solvents as toluene and carbon disulfide, which is important for further purification and characterization.This arc-discharge method can be applied for various metals. Similar results have been obtained in the present laboratory for metals such as yttr...

The morphology and hybridization of nanostructures are crucial to achieve properties for various applications. An in situ grown 3D MoS2 nano-mask has been adopted to control the morphology and hybridization of molybdenum compounds. The in situ generated MoS2 mask on MoO3 nanobelt surfaces allowed us to fabricate a 3D c-MoO2@MoS2 hybrid nanostructure, in which c-MoO2 is a carved MoO2 nanobelt with well distributed hole-pattern. The nano-masks have been controlled by adjusting the alignments of MoS2. The exposed MoO2 surfaces of c-MoO2@MoS2 were further sulphurated to give cw-MoO2@MoS2, in which all surfaces of MoO2 are wrapped by a few layers of MoS2. The structure synergistically enhanced the electrochemical performances of MoO2 and MoS2, especially at high current rates. Reversible capacity of 1418 mAh/g and 295 mAh/g after 115 and 300 cycles are still remained for the cw-MoO2@MoS2 anodes at current rates of 1 A/g and 10 A/g, respectively.

The (6,5) single-wall carbon nanotubes have been preferentially synthesized from a one-dimensional array of C(60) inside single-wall carbon nanotubes (d≅ 1.5 ± 0.1 nm). The as-produced inner tubes have been extracted via sonication and density gradient ultracentrifugation methods and demonstrated to be dominated by (6,5) tubes by optical absorption, Raman scattering, photoluminescence, high-resolution transmission electron microscope observation, and a semi-empirical simulation (PM3).