Graphene Nanoscrolls Research Articles

Contact Effect On Twisted Graphene Based Schottky Transistor

Owing to the exceptional electrical properties of different one dimensional (1D) classifications of graphene structure such as graphene nanoribbon (GNR) and twisted graphene (TWG) led to a revolution in nanoelectronic researche and applications. Thus, these materials have been extensively explored in nanoelectronics science and materials. This paper is focused on GNR and TWG junction as metal-semiconductor-metal (MSM) in the form of a transistor. The wave vectors of TWG and GNR based on the geometrical effects are discussed. By considering 1D potential barrier at the junction of TWG as a semiconducting region and GNR as a metallic region, the transmission probability is calculated. Then, the I–V characteristics of GNR-TWG Schottky transistor based on quantum tunneling effect arepresented and discussed, as well. The performance of GNR-TWG Schottky transistor under variation of gate-source voltage, channel length, number of twists, width of GNR, and temperature are investigated. It is concluded that increment in number of twists and width of GNR lead to increasing the drain current and threshold voltage. Finally, comparison study with graphene nanoscroll (GNS) Schottky transistor, trilayer graphene nanoribbon (TGNR) Schottky transistor, and reported experimental data are performed and results represent that GNR-TWG Schottky transistor has larger drain current than these works.

Acidity-dependent self-rolling of graphene oxide nanoscrolls via metal cation-π interaction

Graphene nanoscrolls with one-dimensional topological structure obtained by Archimedean-type spirals of graphene, inherit the intrinsic properties of the pristine graphene. They have some unique advantages, including open edges/ends, adjustable internal volume, and diameter. Notably, the accommodation of functionalized components in their open interlayer is potentially a fantastic strategy to promote the epoch-making progress in nanotechnology areas, including energy storage, environmental remediation, biotechnology, and smart devices. However, it could destroy the driving forces for the self-rolling of graphene nanosheets and thus it is still a challenge to prepare functionalized graphene nanoscrolls. Here, based on density functional theory prediction, we reported a feasible method to fabricate graphene oxide nanoscrolls with carbon nanotubes as the template. The method was driven by cation-π interactions, which were caused by metal cations that also acted as the adsorption center. Most importantly, the distinct mechanism and an acidity-dependent rule for the formation of graphene nanoscrolls were identified. Benefiting from the introduced metal cations and the macro three-dimensional hierarchical structure, the produced nanoscroll aerogel exhibited significantly improved adsorption performance toward different organic solvents with the adsorption capacities from 129.9 to 265.7 g g−1. This work demonstrates a simple and efficient strategy to fabricate functionalized component-accommodated graphene nanoscroll, which could find important applications in various fields.

Schemes for Single Electron Transistor Based on Double Quantum Dot Islands Utilizing a Graphene Nanoscroll, Carbon Nanotube and Fullerene.

The single electron transistor (SET) is a nanoscale switching device with a simple equivalent circuit. It can work very fast as it is based on the tunneling of single electrons. Its nanostructure contains a quantum dot island whose material impacts on the device operation. Carbon allotropes such as fullerene (C60), carbon nanotubes (CNTs) and graphene nanoscrolls (GNSs) can be utilized as the quantum dot island in SETs. In this study, multiple quantum dot islands such as GNS-CNT and GNS-C60 are utilized in SET devices. The currents of two counterpart devices are modeled and analyzed. The impacts of important parameters such as temperature and applied gate voltage on the current of two SETs are investigated using proposed mathematical models. Moreover, the impacts of CNT length, fullerene diameter, GNS length, and GNS spiral length and number of turns on the SET’s current are explored. Additionally, the Coulomb blockade ranges (CB) of the two SETs are compared. The results reveal that the GNS-CNT SET has a lower Coulomb blockade range and a higher current than the GNS-C60 SET. Their charge stability diagrams indicate that the GNS-CNT SET has smaller Coulomb diamond areas, zero-current regions, and zero-conductance regions than the GNS-C60 SET.

Microwave-assisted synthesis of NiCo-LDH/graphene nanoscrolls composite for supercapacitor

To enhance the electrochemical performance of electrode materials for energy storage devices, utilization the synergistic effect of EDLC-capacitance and pseudocapacitance as well as modification nanostructures are general strategies. Herein, we report the design and synthesis of an array core-shell heterostructure graphene nanoscrolls composite, in which petal-like NiCo-LDH nanoflakes are vertically anchored on the 3D interconnected GNSs skeleton, accomplished by a highly facile microwave-assisted method. This design combines several advantages, including providing more active sites for pseudocapacitive reactions, promoting the collection/transport of electrons and ions, and buffering the volume variation of active matters during cycling. Benefiting from the advantageous nanostructure, the as-obtained NiCo-LDH@GNSs electrode exhibits a high specific capacitance of 1470 F g−1 at a current density of 1 A g−1 and a long cycle life with 81.6% retention after 1000 cycles.

Crystallization Kinetics of Poly(lactic acid)–Graphene Nanoscroll Nanocomposites: Role of Tubular, Planar, and Scrolled Carbon Nanoparticles

Graphene nanoscrolls (GNS) are 1D carbon-based nanoparticles. In this study, they were investigated as a heterogeneous nucleating agent in the poly(lactic acid) (PLA) matrix. The isothermal and non-isothermal melting behavior and crystallization kinetics of PLA-GNS nanocomposites were investigated using a differential scanning calorimeter (DSC). Low GNS content not only accelerated the crystallization rate, but also the degree of crystallinity of PLA. The Avrami model was used to fit raw experimental data, and to evaluate the crystallization kinetics for both isothermal and non-isothermal runs through the nucleation and growth rate. Additionally, the effect of the dimensionality and structure of the nanoparticle on the crystallization behavior and kinetics of PLA is discussed. GNS, having a similar fundamental unit as CNT and GNP, were observed to possess superior mechanical properties when analyzed by the nanoindentation technique. The scrolled architecture of GNS facilitated a better interface and increased energy absorption with PLA compared to CNTs and GNPs, resulting in superior mechanical properties.

Regulating Vacuum Tribological Behavior of a-C:H Film by Interfacial Activity.

A hydrogenated amorphous carbon (a-C:H) film shows an ultralow friction coefficient (COF, lower than 0.01); however, its wear life is short in vacuum, and the mechanisms are still not well-understood. This study demonstrates the vacuum tribological behaviors of the a-C:H film can be regulated by interfacial activity. The strong interfacial activity induced continuous transfer of carbon from the film to counterface, causing the formation of a porous transfer film and severe wear of the a-C:H film. Interestingly, weak interfacial activity is beneficial to form spherical-like carbon at the sliding interface, which shields the interaction of dangling bonds and contributes to lower COF and wear of film. Notably, the catalytic nature of Au induced perfect graphene nanoscrolls around Au nanoparticles at the sliding interface, achieving ultralong vacuum wear life. This Letter unifies the understanding of vacuum tribological properties of a-C:H film and provides new insight for prolonging the life of carbon films in vacuum.

Role of nanoparticles in achieving macroscale superlubricity of graphene/nano-SiO2 particle composites

Recent studies have reported that adding nanoparticles to graphene enables macroscale superlubricity to be achieved. This study focuses on the role of nanoparticles in achieving superlubricity. First, because graphene nanoscrolls can be formed with nanoparticles as seeds under shear force, the applied load (or shear force) is adjusted to manipulate the formation of graphene nanoscrolls and to reveal the relationship between graphene-nanoscroll formation and superlubricating performance. Second, the load-carrying role of spherical nano-SiO2 particles during the friction process is verified by comparison with an elaborately designed fullerene that possesses a hollow-structured graphene nanoscroll. Results indicate that the incorporated nano-SiO2 particles have two roles in promoting the formation of graphene nanoscrolls and exhibiting load-carrying capacity to support macroscale forces for achieving macroscale superlubricity. Finally, macroscale superlubricity (friction coefficient: 0.006–0.008) can be achieved under a properly tuned applied load (2.0 N) using a simple material system in which a graphene/nano-SiO2 particle composite coating slides against a steel counterpart ball without a decorated diamond-like carbon film. The approach described in this study could be of significance in engineering.

Dynamical formation of graphene and graphane nanoscrolls

Carbon nanoscrolls (CNSs) are nanomaterials with geometry resembling graphene layers rolled up into a spiral (papyrus-like) form. Effects of hydrogenation and temperature on the self-scrolling process of two nanoribbons interacting with a carbon nanotube (CNT) have been studied by molecular dynamics simulations for three configurations: (1) graphene/graphene/CNT; (2) graphene/graphane/CNT, and (3) graphane/graphane/CNT. Graphane refers to a fully hydrogenated graphene nanoribbon. Nanoscroll formation is observed for configurations (1) and (2) for temperatures 300–1000 K, while nanoribbons wrap CNT without nanoscroll formation for configuration (3).

Exploration of fast ion diffusion kinetics in graphene nanoscrolls encapsulated CoSe2 as advanced anode for high-rate sodium-ion batteries

Sodium-ion batteries (SIBs) have drawn much attention due to the abundance and low cost of sodium. However, electrode materials of SIBs displayed sluggish Na+ diffusivity and fatal volume expansion, owing to the larger ionic radius of Na+ ions than Li+ ions. In this work, we built the CoSe2 nanoparticles embedded in graphene nanoscrolls (GNS) as advanced anodes for high-rate SIBs. The CoSe2/C@GNS anodes exhibited a high reversible capacity of 545 mA h g−1 at 0.2 A g−1. Moreover, they showed an outstanding cycling stability of 455 mA h g−1 after 5000 cycles at 1 A g−1, with a capacity retention of 92% calculated from 10th cycle. The CoSe2/C@GNS anode also demonstrate ultrahigh rate capabilities (212.5 mAh g−1 at 50 A g−1). In addition, with a high mass loading (6 mg cm−2), the electrode still displayed a stable capacity (412 mA h g−1 1 A g−1). The fast electron transfer and Na+ ion diffusion kinetics creates the excellent electrochemical properties, on account of the uniform arrangement of nanoparticles and unique reticular crosslinking structure of CoSe2/C@GNS. This strategy could also be constructed other electrode materials, which provides more probabilities for the development of SIBs.

Steady self-scrolling of graphene sheets upon the solvation status of adsorbed polyhexylthiophene

Upon the tuning of solvent composition, the unfavorable solvation of adsorbed polyhexylthiophene is found able to drive graphene sheets to scroll steadily in solutions, resulting in nanoscrolls with a central void and regular stacking of internal layers. For theses steadily evolved graphene nanoscrolls, the interlayer distance is subject to the average radius of adsorbed molecular coils and the bending rigidity of graphene hexagonal structural units restricts the reachable curvature of central voids. When the unfavorable solvation is progressively lessened upon slow crystallization of adsorbed polyhexylthiophene molecules, the reverse unwrapping ensues accordingly. On the other hand, the solvent evaporation initiates the dense growth of crystalline whiskers outward from graphene nanoscrolls and thus results in comb-like superstructures. With mutual impingement effects associated with present superstructures, oriented assembly and growth behaviors of crystalline whiskers are able to occur, creating nematic fields of crystalline whiskers.

Characterization of swelling behavior of carbon nano-filler modified polydimethylsiloxane composites.

Polymers may absorb fluids from their surroundings via the natural phenomenon of swelling. Dimensional changes due to swelling can affect the function of polymer components, such as in the case of seals, microfluidic components and electromechanical sensors. An understanding of the swelling behavior of polymers and means for controlling it can improve the design of polymer components, for example, for the previously mentioned applications. Carbon-based fillers have risen in popularity to be used for the property enhancement of resulting polymer composites. The present investigation focuses on the effects of three carbon-based nano-fillers (graphene nano-platelets, carbon black, and graphene nano-scrolls) on the dimensional changes of polydimethylsiloxane composites due to swelling when immersed in certain organic solvents. For this study, a facile and expedient methodology comprised of optical measurements in conjunction with digital image analysis was developed as the primary experimental technique to quantify swelling dimensional changes of the prepared composites. Other experimental techniques assessed polymer cross-linking densities and elastic mechanical properties of the various materials. The study revealed that the addition of certain carbon-based nano-fillers increased the overall swelling of the composites. The extent of swelling further depended on the organic solvent in which the composites were immersed in. Experimental findings are contrasted with published models for swelling prediction, and the role of filler morphology on swelling behavior is discussed.

Graphene nanoscrolls-wrapped oxygen-deficient ZnSb2O6-x nanospheres for enhanced lithium-ion storage

Although polyantimonic acid (PAA, H2Sb2O6·nH2O) possesses a high theoretical specific capacity for lithium-ion storage, its development is hindered by ultralow intrinsic electrical conductivity (∼10−10 S cm−1). In addition, the existence of proton/crystal water and large volume change during electrochemical reaction will impair its cycling stability. Here, oxygen-deficient zinc antimonate (ZnSb2O6-x) nanospheres were designed and synthesized by a facile precipitation-calcination method and then wrapped/confined in 1D graphene nanoscrolls (GS) through graphene self-scrolling strategy. The change from “acid” to “salt” can not only endow zinc antimonate with a higher electrical conductivity (∼1.9 × 10−3 S cm−1) but also remove the proton/crystal water. The encapsulation of GS can accommodate the volume expansion of internal ZnSb2O6-x nanospheres, prevent the loss of active species and further accelerate the transport of electrons (23 S cm−1). Therefore, the resultant ZnSb2O6-x@GS shows high reversible capacity (755 mAh g−1 at 0.1 A g−1), good rate capability (401 and 331 mAh g−1 at 5 and 10 A g−1), and long cycling performance (727 mAh g−1 after 800 cycles at 1 A g−1). These results exhibit the application potential of the ZnSb2O6-x@GS anode material and prove the effectiveness of the composition and structure design.

Silicon Doping Effect on the Electronic Behavior of Graphene Nanoscrolls

The rising demand for developed electronics has led researchers to explore new design approaches using new materials and processes. The current device scaling using these new nanomaterials in advanced fabrication processes greatly improves the overall efficiency and performance of various electronic designs. In this study, the electronic behavior of all types of silicon-doped carbon nanoscrolls including armchair, zigzag, and chiral carbon nanoscrolls is investigated. Although the electronic properties of silicon carbide-based nanostructures and methods of synthesis have garnered great research attention in recent years, to date there have been no studies investigating analytical models or numerical simulation for the energy band structures and electronic characteristics of silicon carbide nanoscrolls. This paper presents a detailed analytical model of the energy band structure for various chiralities of silicon-doped graphene nanoscrolls and silicon carbide nanoscrolls. Our numerical results reveal metallic behavior for most small-diameter armchair Si-doped carbon nanoscrolls. However, for a given (n,n) armchair nanoscroll, the nanoscroll is a semiconductor if n is a multiple of 3. This is due to the effect of the quantization line intersection at the Dirac points. For larger diameters of armchair Si-doped carbon nanoscrolls, there is a small band gap between the associated valence and the conduction band which translates to semiconducting behavior.ae Our numerical study illustrates zero band gap for small-diameter zigzag silicon carbide nanoscrolls, which leads to metallic properties, while in larger nanoscrolls a small energy gap is seen. It seems that the associated energy gap is changed according to the overlap of the first spiral turn with the other turns. Also, the presence of variable small band gaps between the associated valence and conduction bands in large-diameter chiral nanoscrolls reveals that chiral Si-doped carbon nanoscrolls mainly exhibit semiconducting behavior. In the end, all the numerical results are tabulated as a periodic table in which a symmetric arrangement with respect to the armchair nanoscrolls is observed, and as a table diagonal data for the chiral Si-doped carbon nanoscrolls. Moreover, the effects of length variations on the energy structure of silicon carbide nanoscrolls is highlighted in the study.

The current analysis of a single electron transistor based on double graphene nanoscroll island

The single electron transistor (SET) is nanoscale device which operates fast based on tunneling of single electrons in potential barriers. It has low energy consumption, small size and simplified equivalent circuit. This transistor contains source, gate, drain electrodes and an island which is surrounded with three electrodes. The material of SET island affects on operation of this device therefore graphene as a famous carbon based material is selected for the island. Two islands comprised of graphene nanoribbon (GNR) and graphene nanoscroll (GNS) are chosen for SET. The GNS-SET has lower coulomb blockade region and coulomb diamond area than GNR-SET. Moreover the double GNR-SET and double GNS-SET are simulated and their charge stability diagrams are compared together. The result shows that double GNS-SET has lower zero current region and better operation than double GNR-SET. Therefore double GNS is selected for SET island and impact of important parameters on its current are comprehensively investigated. The increasing applied gate voltage, temperature, GNS length and GNS spiral length lead to current increase in double GNS-SET. Moreover, decreasing the number of turns for GNS increases the current in double GNS-SET. These parameters can be utilized for controlling and tunable current in double GNS SET.

One dimensional graphene nanoscroll-wrapped MnO nanoparticles for high-performance lithium ion hybrid capacitors

We demonstrate a simple strategy for the preparation of 1D graphene nanoscroll wrapped MnO nanoparticles (GNS@MnO) as high-rate anode materials for lithium ion hybrid capacitors.

Origin of low friction in hydrogenated diamond-like carbon films due to graphene nanoscroll formation depending on sliding mode: Unidirection and reciprocation

The origins of low friction of hydrogenated diamond-like carbon (H-DLC) films depending on unidirectional and reciprocating motions were detected by the analyses of transmission electron microscopy (TEM), Raman spectroscopy and atomic force microscopy (AFM). Under the comparable experimental conditions, the reciprocating sliding of H-DLC films against a steel ball in humid air enables the stable friction coefficient to lower more than 70% but the surface wear to increase 50% compared to the unidirectional sliding. The uniformity and structure of transfer layer and worn H-DLC surface strongly depend on sliding motions. Two-way movements in the reciprocating sliding help to keep the transfer layer within contact region, enhancing its graphitization. TEM image of transfer layer shows the formation of abundant graphene nanoscrolls in reciprocating sliding but only few graphite layers in unidirectional sliding. AFM results and Raman spectra suggest that not only the transfer layer but also the graphitization of the rough worn H-DLC surface induced by high alternating stress plays a significant role in the low friction under reciprocating motion. Combining the atomic-scale, nanoscale and macroscale results, a comprehensive model is proposed for the statement of low friction sliding contact of H-DLC films depending on the sliding motions.

Robust and durable flexible micro-supercapacitors enabled by graphene nanoscrolls

The rise of miniaturized, flexible and self-powered electronic systems has substantially stimulated the urgent demand for microscale electrochemical energy storage devices. Impressively, planar micro-supercapacitors (MSCs) are playing a crucial role because of fast ion transmission, ultra-long lifetime, and being easily integrated with microelectronic devices. Unfortunately, the robustness of film electrodes in MSCs usually cannot satisfy the structural stability of the film electrodes and the durability of the devices. Here, a novel strategy to address the problem is proposed by introducing graphene nanoscrolls with high aspect ratio as the active materials in the flexible MSCs to enhance the robustness of the film electrode because of their intertwined one-dimensional nanostructures. The as-prepared bendable MSC can maintain nearly 100% of initial capacitance when bent for 1000 cycles, and the stretchable MSC can maintain 88% of initial capacitance when stretched at a high stress ratio of 100% for 1000 cycles. This study provides an effective strategy to build up robust film electrodes for MSCs and improve the durability of the flexible MSCs.

Nitrogen-doped holey graphene nanoscrolls for high-energy and high-power supercapacitors

Porous structure and heteroatom doping are two key parameters for significantly boosting the capacitive performance of graphene-based materials. Herein, we report a facile approach to prepare one-dimensional (1D) nitrogen-doped holey graphene nanoscrolls (NHGNSs) through cold quenching treatment of two-dimensional graphene oxide sheets, followed by thermal annealing in the successive atmosphere of NH3 and air. Benefiting from the synergy of the unique 1D tubular morphology, abundant nanoholes and nitrogen doping, the NHGNSs exhibit a high specific capacitance of 126 F/g at 1 A/g in ionic liquid electrolyte and excellent rate capability with 81% of the capacitance retained at 20 A/g. Furthermore, the fabricated symmetric supercapacitors based on NHGNSs achieve both high energy density of 53.5 Wh/kg at 875 W/kg and high power density of 17.5 kW/kg at 43.4 Wh/kg. The simple synthetic process and superior electrochemical performance suggest the great potential of NHGNSs for supercapacitor application.

Structure original of temperature depended superlow friction behavior of diamond like carbon

As one kind of traditional and widely used solid lubricant, diamond like carbon films have been approved to have temperature dependent ultra-low friction behaviors. However, the mechanism of this observation is not fully clarified. By using high resolution transmission electron microscopy, Raman spectrum and tribometer, we monitored the nanostructure transformation of wear debris and friction coefficient evolution from 25 °C to 200 °C. High temperature promotes graphitization and enhances the formation of graphene nanoscrolls (GNSs), which results in decrease of friction coefficient. For example, at 150 °C, more spherical shape graphene nanoscrolls appear in debris and a balance between graphitization and nanoscrolls crimping is established, which leads to the lowest friction coefficient at 0.012. However, when the temperature is too high (200 °C), such a balance is destroyed and the nanoscrolls tend to be disordered with sharp edges, which causes the failing of superlow friction state. The results demonstrated that temperature could change the fine structure of graphene nanoscrolls, which ultimately determines the tribological behavior of DLC film. Moreover, the structure evolution of graphene nanoscrolls should be the compulsory result of competition between the thermodynamic formation of graphene layers and the dynamics of nanoscrolls crimping.

Superlubricity of carbon nanostructural films enhanced by graphene nanoscrolls

Recently, macroscopic superlubricity has been realized by forming spherical geometries at a sliding interface to cause nanoscopic point contact. Here, we showed macroscopic superlubricity (~0.005) enhanced by graphene nanoscrolls, which were formed at the sliding interface of a tribological pair composed of graphite-like and fullerene-like hydrogenated carbon films.