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The drive for significant advancement in battery capacity and energy density inspired a revisit to the use of Li metal anodes. We report the use of a seamless graphene–carbon nanotube (GCNT) electrode to reversibly store Li metal with complete dendrite formation suppression. The GCNT-Li capacity of 3351 mAh g–1GCNT-Li approaches that of bare Li metal (3861 mAh g–1Li), indicating the low contributing mass of GCNT, while yielding a practical areal capacity up to 4 mAh cm–2 and cycle stability. A full battery based on GCNT-Li/sulfurized carbon (SC) is demonstrated with high energy density (752 Wh kg–1 total electrodes, where total electrodes = GCNT-Li + SC + binder), high areal capacity (2 mAh cm–2), and cyclability (80% retention at >500 cycles) and is free of Li polysulfides and dendrites that would cause severe capacity fade.

Here we show that a versatile binary catalyst solution of Fe3O4/AlOx nanoparticles enables homogeneous growth of single to few-walled carbon nanotube (CNT) carpets from three-dimensional carbon-based substrates, moving past existing two-dimensional limited growth methods. The binary catalyst is composed of amorphous AlOx nanoclusters over Fe3O4 crystalline nanoparticles, facilitating the creation of seamless junctions between the CNTs and the underlying carbon platform. The resulting graphene-CNT (GCNT) structure is a high-density CNT carpet ohmically connected to the carbon substrate, an important feature for advanced carbon electronics. As a demonstration of the utility of this approach, we use GCNTs as anodes and cathodes in binder-free lithium-ion capacitors, producing stable devices with high-energy densities (∼120 Wh kg–1), high-power density capabilities (∼20,500 W kg–1 at 29 Wh kg–1), and a large operating voltage window (4.3 to 0.01 V).

We report that conductive films made from hexadecylated graphene nanoribbons (HD-GNRs) can have high transparency to radiofrequency (RF) waves even at very high incident power density. Nanoscale-thick HD-GNR films with an area of several square centimeters were found to transmit up to 390 W (2 × 10(5) W/m(2)) of RF power with negligible loss, at an RF transmittance of ∼99%. The HD-GNR films conformed to electromagnetic skin depth theory, which effectively accounts for the RF transmission. The HD-GNR films also exhibited sufficient optical transparency for tinted glass applications, with efficient voltage-induced deicing of surfaces. The dispersion of the HD-GNRs afforded by their edge functionalization enables spray-, spin-, or blade-coating on almost any substrate, thus facilitating flexible, conformal, and large-scale film production. In addition to use in antennas and radomes where RF transparency is crucial, these capabilities bode well for the use of the HD-GNR films in automotive and general glass applications where both optical and RF transparencies are desired.

A composite material made of graphene nanoribbons and iron oxide nanoparticles provides a remarkable route to lithium-ion battery anode with high specific capacity and cycle stability. At a rate of 100 mA/g, the material exhibits a high discharge capacity of ~910 mAh/g after 134 cycles, which is >90% of the theoretical li-ion storage capacity of iron oxide. Carbon black, carbon nanotubes, and graphene flakes have been employed by researchers to achieve conductivity and stability in lithium-ion electrode materials. Herein, the use of graphene nanoribbons as a conductive platform on which iron oxide nanoparticles are formed combines the advantages of long carbon nanotubes and flat graphene surfaces. The high capacity over prolonged cycling achieved is due to the synergy between an electrically percolating networks of conductive graphene nanoribbons and the high lithium-ion storage capability of iron oxide nanoparticles.

Silver-graphene nanoribbons (Ag-GNRs) were prepared from the chemical unzipping of multiwalled carbon nanotubes (MWCNTs) by reaction with Na/K alloy, Ag(O2CCH3) and then CH3OH. Ag-GNRs exhibited improved electrocatalytic ability for the oxygen reduction reaction (ORR) in 0.1 M KOH as compared to the underlying GNR substrate alone and displayed an earlier onset and higher currents than a commercial Ag/Carbon (Ag/C) catalyst. The Ag-GNR hybrid demonstrates an outstanding tolerance to CH3OH crossover which exceeds that of the commercial benchmark, 20 % Pt/C.

Anti-icing and deicing are the two major pathways for suppressing adhesion of ice on surfaces, yet materials with dual capabilities are rare. In this work, we have designed a perfluorododecylated graphene nanoribbon (FDO-GNR) film that takes advantage of both the low polarizability of perfluorinated carbons and the intrinsic conductive nature of graphene nanoribbons. The FDO-GNR films are superhydrophobic with a sheet resistance below 8 kΩ·sq(-1) and then exhibit an anti-icing property that prevents freezing of incoming ice-cold water down to -14 °C. After that point, voltage can be applied to the films to resistively heat and deice the surface. Further a lubricating liquid can be employed to create a slippery surface to improve the film's deicing performance. The FDO-GNR films can be easily switched between the superhydrophobic anti-icing mode and the slippery deicing mode by applying the lubricant. A spray-coating method makes it suitable for large-scale applications. The anti-icing and deicing properties render the FDO-GNR films with promise for use in extreme environments.

A conductive composite of graphene nanoribbon (GNR) stacks and epoxy is fabricated. The epoxy is filled with the GNR stacks, which serve as a conductive additive. The GNR stacks are on average 30 nm thick, 250 nm wide, and 30 μm long. The GNR-filled epoxy composite exhibits a conductivity >100 S/m at 5 wt % GNR content. This permits application of the GNR-epoxy composite for deicing of surfaces through Joule (voltage-induced) heating generated by the voltage across the composite. A power density of 0.5 W/cm2 was delivered to remove ∼1 cm-thick (14 g) monolith of ice from a static helicopter rotor blade surface in a −20 °C environment.

A cost-effective and potentially industrially scalable, in situ functionalization procedure for preparation of soluble graphene nanoribbon (GNRs) from commercially available carbon nanotubes is presented. The physical characteristics of the functionalized product were determined using SEM, evolved gas analysis, X-ray diffraction, solid-state (13)C NMR, Raman spectroscopy, and GC-MS analytical techniques. A relatively high preservation of electrical properties in the bulk material was observed. Moreover, replacement of intercalated potassium with haloalkanes was obtained. While carbon nanotubes can be covalently functionalized, the conversion of the sp(2)-hybridized carbon atoms to sp(3)-hybridized atoms dramatically lowers their conductivity, but edge functionalized GNRs permit their heavy functionalization while leaving the basal planes intact.

A nanocomposite material made of layered tin disulfide (SnS2) nanoplates vertically grown on reduced graphene oxide nanoribbons (rGONRs) has been successfully developed as an anode in lithium ion batteries by a facile method. At a rate of 0.4 A/g, the material exhibits a high discharge capacity of 823 mAh/g even after 800 cycles. It shows excellent rate stability when the current density varies from 0.1 to 3.0 A/g with a Coulombic efficiency larger than 99%. In order to demonstrate the anode material for practical applications, SnS2-rGONR/LiCoO2 full cells were constructed. To the best of our knowledge, this is the first time that a full cell has been successfully developed using metal chalcogenides as an anode. The full cell delivers a high capacity of 642 mAh/g at 0.2 A/g, superior rate, and cycling stability after long-term cycling. Moreover, the full cell has a high output working voltage of 3.4 V. These excellent lithium storage performances in half and full cells can be mainly attributed to the synergistic effect between the highly conductive network of rGONRs and the high lithium-ion storage capability of layered SnS2 nanoplates.

Nature Communications 4: Article number: 2943 (2013); Published: 6 December 2013; Updated: 23 April 2015. In this Article, the bituminous coal graphene quantum dots (b-GQD) are described throughout this paper as having a crystalline hexagonal structure. Following further careful study of the high-resolution transmission electron microscopy data, this claim is too rigorous, and the b-GQDs instead should be referred to as crystalline.

A hierarchical nanocomposite material of graphene nanoribbons combined with polyaniline and sulfur using an inexpensive, simple method has been developed. The resulting composite, characterized by scanning electron microscopy, transmission electron microscopy, X-ray photoelectron microscopy, and X-ray diffraction analysis, has a good rate performance and excellent cycling stability. The synergistic combination of electrically conductive graphene nanoribbons, polyaniline, and sulfur produces a composite with high performance. The method developed here is practical for the large-scale development of cathode materials for lithium sulfur batteries.

Anti-icing and de-icing heaters layers are frequently used in covers of large radio frequency (RF) equipment, such as radar or communication antennas, to prevent ice accumulation or completely remove it avoiding possible structure damage or service disruption. Typically the de-icing structures are produced using a metal framework and inorganic insulator and generally bulky, heavy and costly. In this report, we disclose a new de-icing heater layer composite made using graphene nanoribbons (GNRs). We demonstrate that the conductive GNR film is thin enough to be transparent for broadband RF signal of any polarization with minimal impact on antenna scan performance. This metal-free, ultra-light, robust and scalable graphene-based RF transparent conductive coating could significantly reduce the size and cost of de-icing/anti-icing coating and could be important in many aviation and military applications. This is a demonstration of the efficacy and applicability of graphene to afford performances unattainable by conventional materials.

SiOx memory devices that offer significant improvement in switching performance were fabricated at room temperature with conducting interlayers such as Pd, Ti, carbon, or multilayer graphene. In particular, the Pd-interlayer SiOx memory devices exhibited improvements in lowering the electroforming voltages and threshold voltages as the number of inserted Pd layers was increased, as compared to a pure SiOx memory structure. In addition, we demonstrated that the Pd-interlayer SiOx junction fabricated on a flexible substrate maintained low electroforming voltage and mechanically stable switching properties. From these observations, a possible switching mechanism is discussed based on the formation of individual conducting paths at the weakest edge regions of each SiOx film, where the normalized bond-breaking probability of SiOx is influenced by the voltage and the thickness of SiOx. This fabrication approach offers a useful structural platform for next-generation memory applications for enhancement of the switching properties while maintaining a low-temperature fabrication method that is even amenable with flexible substrates.

Deicing heating layers are frequently used in covers of large radio-frequency (RF) equipment, such as radar, to remove ice that could damage the structures or make them unstable. Typically, the deicers are made using a metal framework and inorganic insulator; commercial resistive heating materials are often nontransparent to RF waves. The preparation of a sub-skin-depth thin film, whose thickness is very small relative to the RF skin (or penetration) depth, is the key to minimizing the RF absorption. The skin depth of typical metals is on the order of a micrometer at the gigahertz frequency range. As a result, it is very difficult for conventional conductive materials (such as metals) to form large-area sub-skin-depth films. In this report, we disclose a new deicing heating layer composite made using graphene nanoribbons (GNRs). We demonstrate that the GNR film is thin enough to permit RF transmission. This metal-free, ultralight, robust, and scalable graphene-based RF-transparent conductive coating could significantly reduce the size and cost of deicing coatings for RF equipment covers. This is important in many aviation and marine applications. This is a demonstration of the efficacy and applicability of GNRs to afford performances unattainable by conventional materials.

Coal is the most abundant and readily combustible energy resource being used worldwide. However, its structural characteristic creates a perception that coal is only useful for producing energy via burning. Here we report a facile approach to synthesize tunable graphene quantum dots from various types of coal, and establish that the unique coal structure has an advantage over pure sp2-carbon allotropes for producing quantum dots. The crystalline carbon within the coal structure is easier to oxidatively displace than when pure sp2-carbon structures are used, resulting in nanometre-sized graphene quantum dots with amorphous carbon addends on the edges. The synthesized graphene quantum dots, produced in up to 20% isolated yield from coal, are soluble and fluorescent in aqueous solution, providing promise for applications in areas such as bioimaging, biomedicine, photovoltaics and optoelectronics, in addition to being inexpensive additives for structural composites.

Anti-icing and de-icing heaters layers are frequently used in covers of large radio frequency (RF) equipment, such as radar or communication antennas, to prevent ice accumulation or completely remove it avoiding possible structure damage or service disruption. Typically the de-icing structures are produced using a metal framework and inorganic insulator and generally bulky, heavy and costly. In this report, we disclose a new de-icing heater layer composite made using graphene nanoribbons (GNRs). We demonstrate that the conductive GNR film is thin enough to be transparent for broadband RF signal of any polarization with minimal impact on antenna scan performance. This metal-free, ultra-light, robust and scalable graphene-based RF transparent conductive coating could significantly reduce the size and cost of de-icing/anti-icing coating and could be important in many aviation and military applications. This is a demonstration of the efficacy and applicability of graphene to afford performances unattainable by conventional materials.

Precise spatial control of materials is the key capability of engineering their optical, electronic, and mechanical properties. However, growth of graphene on Cu was revealed to be seed-induced two-dimensional (2D) growth, limiting the synthesis of complex graphene spatial structures. In this research, we report the growth of onion ring like three-dimensional (3D) graphene structures, which are comprised of concentric one-dimensional hexagonal graphene ribbon rings grown under 2D single-crystal monolayer graphene domains. The ring formation arises from the hydrogenation-induced edge nucleation and 3D growth of a new graphene layer on the edge and under the previous one, as supported by first principles calculations. This work reveals a new graphene-nucleation mechanism and could also offer impetus for the design of new 3D spatial structures of graphene or other 2D layered materials. Additionally, in this research, two special features of this new 3D graphene structure were demonstrated, including nanoribbon fabrication and potential use in lithium storage upon scaling.

A facile and cost-effective approach for the fabrication of a hierarchical nanocomposite material of graphene-wrapped MnO2 -graphene nanoribbons (GMG) is developed. The resulting composite has a high specific capacity and an excellent cycling stability owing to the synergistic combination of the electrically conductive graphene, graphene nanoribbons, and MnO2 .

Described here is the production and characterization of a scalable method to produce 3D structured lithium ion battery anodes using free-standing papers of porous silicon nanowires (Si-NW) and graphene nanoribbons (GNRs). Using simple filtration methods, GNRs and Si-NWs can be entangled into a mat thereby forming Si-NW GNR papers. This produces anodes with high gravimetric capacity (up to 2500 mA h g−1) and high areal and volumetric capacities (up to 11 mA h cm−2 and 3960 mA h cm−3). The compact structure of the anode is possible since the GNR volume occupies a high proportion of empty space within the composite paper. These Si-NW/GNR papers have been cycled for over 300 cycles, exhibiting a stable life cycle. Combined with LiCoO2 nanowires, a full battery is produced with high energy density (386 Wh kg−1), meeting requirements for high performance devices.

Graphene and single-walled carbon nanotubes are carbon materials that exhibit excellent electrical conductivities and large specific surface areas. Theoretical work suggested that a covalently bonded graphene/single-walled carbon nanotube hybrid material would extend those properties to three dimensions, and be useful in energy storage and nanoelectronic technologies. Here we disclose a method to bond graphene and single-walled carbon nanotubes seamlessly during the growth stage. The hybrid material exhibits a surface area2,000 m(2) g(-1) with ohmic contact from the vertically aligned single-walled carbon nanotubes to the graphene. Using aberration-corrected scanning transmission electron microscopy, we observed the covalent transformation of sp(2) carbon between the planar graphene and the single-walled carbon nanotubes at the atomic resolution level. These findings provide a new benchmark for understanding the three-dimensional graphene/single-walled carbon nanotube-conjoined materials.

Few-layer graphene, with Bernal stacking order, is of particular interest to the graphene community because of its unique tunable electronic structure. A synthetic method to produce such large area graphene films with precise thickness from 2 to 4 layers would be ideal for chemists and physicists to explore the promising electronic applications of these materials. Here, large-area uniform Bernal-stacked bi-, tri-, and tetralayer graphene films were successfully synthesized on a Cu surface in selective growth windows, with a finely tuned total pressure and CH(4)/H(2) gas ratio. On the basis of the analyses obtained, the growth mechanism is not an independent homoexpitaxial layer-by-layer growth, but most likely a simultaneous-seeding and self-limiting process.

LiFePO4 encapsulated in graphene nanoshells (LiFePO4@GNS) nanoparticles were synthesized by solid state reaction between graphene-coated Fe nanoparticles and LiH2PO4. The resulting nanocomposite was demonstrated to be a superior lithium-ion battery cathode with improved cycle and rate performances.