Sandwich structured graphene-wrapped FeS-graphene nanoribbons (G@FeS-GNRs) were developed. In this composite, FeS nanoparticles were sandwiched between graphene and graphene nanoribbons. When used as anodes in lithium ion batteries (LIBs), the G@FeS-GNR composite demonstrated an outstanding electrochemical performance. This composite showed high reversible capacity, good rate performance, and enhanced cycling stability owing to the synergy between the electrically conductive graphene, graphene nanoribbons, and FeS. The design concept developed here opens up a new avenue for constructing anodes with improved electrochemical stability for LIBs.

A nanocomposite material of SnO₂-reduced graphene oxide nanoribbons has been developed. In this composite, the reduced graphene oxide nanoribbons are uniformly coated by nanosized SnO₂ that formed a thin layer of SnO₂ on the surface. When used as anodes in lithium ion batteries, the composite shows outstanding electrochemical performance with the high reversible discharge capacity of 1, 027 mAh/g at 0.1 A/g after 165 cycles and 640 mAh/g at 3.0 A/g after 160 cycles with current rates varying from 0.1 to 3.0 A/g and no capacity decay after 600 cycles compared to the second cycle at a current density of 1.0 A/g. The high reversible capacity, good rate performance and excellent cycling stability of the composite are due to the synergistic combination of electrically conductive reduced graphene oxide nanoribbons and SnO₂. The method developed here is practical for the large-scale development of anode materials for lithium ion batteries.

The thermal conduction of suspended few-layer hexagonal boron nitride (h-BN) sheets was experimentally investigated using a noncontact micro-Raman spectroscopy method. The first-order temperature coefficients for monolayer (1L), bilayer (2L) and nine-layer (9L) h-BN sheets were measured to be -(3.41 ± 0.12) × 10^-2, -(3.15 ± 0.14) × 10^-2 and -(3.78 ± 0.16) × 10^-2 cm^-1·K^-1, respectively. The room-temperature thermal conductivity of few-layer h-BN sheets was found to be in the range from 227 to 280 W·m^-1·K^-1, which is comparable to that of bulk h-BN, indicating their potential use as important components to solve heat dissipation problems in thermal management configurations.

We report a novel chemical vapor deposition (CVD) based strategy to synthesize carbon-coated Fe₂O₃ nanoparticles dispersed on graphene sheets (Fe₂O₃@C@G). Graphene sheets with high surface area and aspect ratio are chosen as space restrictor to prevent the sintering and aggregation of nanoparticles during high temperature treatments (800 ℃). In the resulting nanocomposite, each individual Fe₂O₃ nanoparticle (5 to 20 nm in diameter) is uniformly coated with a continuous and thin (two to five layers) graphitic carbon shell. Further, the core-shell nanoparticles are evenly distributed on graphene sheets. When used as anode materials for lithium ion batteries, the conductive-additive-free Fe₂O₃@C@G electrode shows outstanding Li⁺ storage properties with large reversible specific capacity (864 mAh/g after 100 cycles), excellent cyclic stability (120% retention after 100 cycles at 100 mA/g), high Coulombic efficiency (~99%), and good rate capability.

Patterning ultrathin MoS₂ layers with regular edges or controllable shapes is appealing since the properties of MoS₂ sheets are sensitive to the edge structures. In this work, we have introduced a simple, effective and well-controlled technique to etch layered MoS₂ sheets with well-oriented equilateral triangular pits by simply heating the samples in air. The anisotropic oxidative etching is greatly affected by the surrounding temperature and the number of MoS₂ layers, whereby the pit sizes increase with the increase of surrounding temperature and the number of MoS₂ layers. First-principles computations have been performed to explain the formation mechanism of the triangular pits. This technique offers an alternative avenue to engineering the structure of MoS₂ sheets.

The electrical properties of chemically derived graphene and graphene grown by chemical vapor deposition (CVD), until now, have been inferior to those of mechanically exfoliated graphene. However, because graphene is easier to produce in large quantities through CVD or growth from solid carbon sources, it has a higher potential for use in future electronics applications. Generally, modifications to the pristine lattice structure of graphene tend to adversely affect the electrical properties by shifting the doping level and changing the conductivity and the mobility. Here we show that a small degree of graphene surface functionalization, using diazonium salts with electron-withdrawing and electron-donating functional groups, is sufficient to predominantly induce p-type doping, undiminished mobility, and higher conductivity at the neutrality point. Molecules without a diazonium anchor group desorb easily and do not have a significant effect on the electronic properties of graphene devices. We further demonstrate the variability between identically fabricated pristine devices, thereby underscoring the caution needed when characterizing graphene device behaviors lest conclusions be drawn based on singular extremes.

A simple one-pot reaction that serves to functionalize graphite nanosheets (graphene) and single-walled carbon nanotubes (SWNTs) with perfluorinated alkyl groups is reported. Free radical addition of 1-iodo-1H, 1H, 2H, 2H-perfluorododecane to ortho-dichlorobenzene suspensions of the carbon nanomaterial is initiated by thermal decomposition of benzoyl peroxide. Similarly, UV photolysis of 1-iodo-perfluorodecane serves to functionalize the carbon materials. Perfluorododecyl-SWNTs, perfluorododecyl-graphene, and perfluorodecyl-graphene are characterized by infrared (IR) and Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), and atomic force microscopy (AFM). The products show enhanced dispersability in CHCl₃ as compared to unfunctionalized starting materials. The advantage of this one-pot functionalization procedure lies in the use of pristine graphite as starting material thereby avoiding the use of harsh oxidizing conditions.

Thermally expanded graphite was functionalized with 4-bromophenyl addends using the in situ diazonium formation procedure, and after mild sonication treatment in N, Nʹ-dimethylformamide, thin graphene layers were exfoliated from the bulk graphite. These chemically-assisted exfoliated graphene (CEG) sheets had higher solubility than pristine graphene without any stabilizer additive. More than 70% of these soluble flakes had less than 5 layers. Energy filtered transmission electron microscopy (EFTEM) elemental mapping provided evidence of the edge-selective diazonium functionalization with graphene. A majority of the Br signals came from the edges of the CEG indicating that the basal planes were not highly functionalized. The CEG was also characterized by X-ray photoelectron spectroscopy, atomic force microscopy, Raman spectroscopy, and transmission electron microscopy.

The strong hydrogen bonding ability of 2-pyridones were exploited to build nanotrains on surfaces. Carborane wheels on axles difunctionalized with 2-pyridone hydrogen bonding units were synthesized and displayed spontaneous formation of linear nanotrains by self-assembly on SiO₂ or mica surfaces. Imaging using atomic force microscopy confirmed linear formations with lengths up to 5 μm and heights within the range of the molecular height of the carborance-tipped axles.