Carbon Nanoscrolls Research Articles

Molecular simulation of adsorption and separation of N2 and CF4 on carbon and boron nitride nanostructures

Grand canonical ensemble Monte Carlo (GCMC) molecular simulations were performed to study CF4 adsorption on carbon nanotubes, boron nitride (BN) nanotubes, carbon nanoscrolls, and BN nanoscrolls. At 298 K and 2 MPa, (15,15) BN nanotubes exhibited 4.57 mmol/g and 98 v/v in excess weight and volume adsorption for CF4, respectively, which is a 50 % and 44 % increase over (15,15) carbon nanotubes at 3.04 mmol/g and 68 v/v. BN nanoscrolls with a 1.3 nm interlayer spacing showed even higher adsorption at 13.63 mmol/g and 145 v/v, a 33 % increase over carbon nanoscrolls with a 10.23 mmol/g and 108 v/v. Utilizing Ideal Adsorbed Solution Theory (IAST), we predicted that (14,14) BN nanotubes would have a CF4 adsorption capacity of 4.27 mmol/g and a selectivity of 6.4 at 298 K and 4 MPa for equimolar CF4/N2 mixtures, surpassing (14,14) carbon nanotubes at 3.01 mmol/g and 4.5. BN nanoscrolls with a 1.2 nm spacing showed a 13.35 mmol/g and 8.1 adsorption capacity and selectivity for CF4, respectively, which is superior to carbon nanoscrolls at 9.33 mmol/g and 5.1. These results outperform other porous materials, indicating that BN nanoscrolls are highly promising for CF4 capture.

Switching Behavior of the Composite Low Dimensional Structural Hybrids of Carbon After UV Exposure

Low dimensional multi structural components of carbon are of great interest currently owing to their applications in developing flexible plastic electronics. In this work, we discuss emergence of different structural hybrids of carbon from as-prepared HiPCO SWCNTs subjecting them to oxidative acid purification and covalent functionalization process. Transmission electron microscopy (TEM) investigations reveal single wall carbon nanotubes (SWCNTs) serve as a building block to obtain multi wall carbon nanotubes (MWCNTs), graphene sheets (GS), carbon nano scrolls (CNS) structures which coexist in the sample. These structures when grafted with polymer binder and spray coated on Si substrate provide highly sustainable thin film coatings that are stable even in adverse space conditions [1]. These CNT and CNS based composite coatings are promising candidates for stray light control space applications exhibiting a low reflectance of the order of 2-3% in the visible spectral range [1]. Electrical switching behaviour of these films were investigated by capturing current(time) (I(t)) response, displaying promising switching character with distinct ON-OFF cycle. These coatings offer opportunities for the development of facile, cost-effective carbon-based devices without going into the nontrivial task of separating different the structures.

Electrical nature of randomly oriented low-dimensional structural hybrids of carbon.

Low-dimensional carbon materials are of great interest and have tremendous potential for application in flexible plastic electronics. However, the development of devices based on carbon structural hybrids is often hindered due to the high recombination rate of photoexcited charges, low absorbance, and other factors. This work discusses the emergence of multi-component structural forms of carbon from single-wall carbon nanotubes (SWCNTs) and demonstrates the electrical nature of the film containing these heterogeneous low-dimensional structural derivatives that are amalgamated in a polyurethane matrix. SWCNTs serve as a building block to give rise to multi-structural compounds, including multi-wall carbon nanotubes (MWCNTs), graphene sheets (GSs), carbon nanoscrolls (CNS), 'Y' and 'T' junctions, twisted CNTs and carbon nano-onion (CNO)-like structures, after performing oxidative purification and covalent functionalization processes. These one- and two-dimensional (1D and 2D) components with different individual electrical characteristics when integrated in a polyurethane binder and spin-coated on a SiO2/Si substrate exhibit an overall semiconducting behaviour. Current (I)-voltage (V) characteristics reveal thermally driven photo-excited charges that are mainly responsible for the observed current trend of the film. Herein, we explore a facile cost-effective strategy to fabricate stable thin film coatings comprising a random network of functionalized structural derivatives of carbon and polymer conjugates and investigate the overall electrical nature to envisage incorporating these nanomaterials in future plastic electronics.

Reversible actuation of α-borophene nanoscrolls.

In this work, we proposed and investigated the structural and electronic properties of boron-based nanoscrolls (armchair and zigzag) using the DFTB+ method. We also investigated the electroactuation process (injecting and removing charges). A giant electroactuation was observed, but the results show relevant differences between the borophene and carbon nanoscrolls. The molecular dynamics simulations showed that the scrolls are thermally and structurally stable for a large range of temperatures (up to 600 K), and the electroactuation process can be easily tuned and can be entirely reversible for some configurations.

Synergistic actuation performance of artificial fern muscle with a double nanocarbon structure

Electrochemically powered carbon nanotube (CNT) yarn muscles are of increasing interest because of their advantageous features as artificial muscles. They are light, and have high electrical properties, mechanical strength, and chemical stability. Twist-based CNT yarn muscles show superior actuation performance: 30 times the work capacity and 85 times the power density of natural muscles. Despite achieving these high performances, there is still potential for performance improvement because their twisted structure is not fully utilized. In particular, designing a cross-sectional structure that allows ions to freely enter and exit the twisted structure of the yarn muscle is necessary. Here, we propose highly enhanced artificial muscles with high chemical stability that consist of only nanocarbon materials of carbon nanoscroll (CNS) and twisted CNT yarns. The CNS/CNT yarn muscles (CCYM) can improve the ion accessibility and utilization of the twist structure. The maximum contractile stroke, work capacity, power density, and energy conversion efficiency of the CCYM were 20.11%, 2.26 J g−1, 0.53 W g−1, and 3.39%, which are 1.4-, 1.4-, 4.8, and 4.3 times that of the pristine CNT yarn muscles, respectively. The effects of CNS on CCYM were confirmed by experimental and theoretical analyses. Additionally, in a solid electrolyte, which opens up new application possibilities, the CCYM demonstrates high actuation performance (16.38%) with very low input energy.

Formation and stability of nanoscrolls composed of graphene and hexagonal boron nitride nanoribbons: insights from molecular dynamics simulations.

Nanoscrolls are tube-shaped structures formed when a sheet or ribbon of material is rolled into a cylinder, creating a hollow tube with a diameter on the nanoscale, similar to the papyrus. Carbon nanoscrolls have unique properties that make them useful in various applications, such as energy storage, catalysis, and drug delivery. In this study, we employed classical molecular dynamics simulations to investigate the formation and stability of nanoscrolls composed of graphene and hexagonal boron nitride (hBN) nanoribbons. Using a carbon nanotube (CNT) as a template to trigger their collapsing, we found that graphene/graphene, graphene/hBN, and hBN/hBN could form CNT-wrapped nanoscrolls at ultrafast speeds. We also confirmed that these nanoscrolls are thermally stable and discussed the other products formed from the interaction of these complexes and their temperature dependence. Gr/Gr and hBN/Gr nanoscrolls exhibit similar interlayer distances, while hBN/hBN nanoscrolls have wider interlayer distances than the other two composite nanoscrolls. These features suggest that hBN/hBN composite nanoscrolls could more efficiently capture small molecules because of their greater interlayer spacing. We conducted molecular dynamics simulations using the Forcite package in the Biovia Materials Studio software, which employs the Universal and Dreiding force fields. We considered an NVT ensemble with a fixed time step of 1.0 fs for a duration of 500 ps. The velocity Verlet algorithm was adopted to integrate the equations of motion of the entire system. We employed the Nosé-Hoover-Langevin thermostat to control the system temperature. The simulations were carried out without periodic boundary conditions, so there was no pressure coupling.

Nitrogen-rich hierarchical porous carbon nanoscrolls with atomically dispersed Co sites for the enhanced oxygen reduction reaction and lithium-ion batteries

Hierarchical porous Co–N–C nanoscrolls are synthesized through a pyrolysis-induced gas diffusion strategy.

Magnetoconductance modulations due to interlayer tunneling in radial superlattices.

Radial superlattices are nanostructured materials obtained by rolling up thin solid films into spiral-like tubular structures. The formation of these "high-order" superlattices from two-dimensional crystals or ultrathin films is expected to result in a transition of transport characteristics from two-dimensional to one-dimensional. Here, we show that a transport hallmark of radial superlattices is the appearance of magnetoconductance modulations in the presence of externally applied axial magnetic fields. This phenomenon critically relies on electronic interlayer tunneling processes that activate an unconventional Aharonov-Bohm-like effect. Using a combination of density functional theory calculations and low-energy continuum models, we determine the electronic states of a paradigmatic single-material radial superlattice - a two-winding carbon nanoscroll - and indeed show momentum-dependent oscillations of the magnetic states in the axial configuration, which we demonstrate to be entirely due to hopping between the two windings of the spiral-shaped scroll.

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).

Structure and Thermodynamics of Silicon Oxycarbide Polymer-Derived Ceramics with and without Mixed-Bonding.

Silicon oxycarbides synthesized through a conventional polymeric route show characteristic nanodomains that consist of sp2 hybridized carbon, tetrahedrally coordinated SiO4, and tetrahedrally coordinated silicon with carbon substitution for oxygen, called “mixed bonds.” Here we synthesize two preceramic polymers possessing both phenyl substituents as unique organic groups. In one precursor, the phenyl group is directly bonded to silicon, resulting in a SiOC polymer-derived ceramic (PDC) with mixed bonding. In the other precursor, the phenyl group is bonded to the silicon through Si-O-C bridges, which results in a SiOC PDC without mixed bonding. Radial breathing-like mode bands in the Raman spectra reveal that SiOC PDCs contain carbon nanoscrolls with spiral-like rolled-up geometry and open edges at the ends of their structure. Calorimetric measurements of the heat of dissolution in a molten salt solvent show that the SiOC PDCs with mixed bonding have negative enthalpies of formation with respect to crystalline components (silicon carbide, cristobalite, and graphite) and are more thermodynamically stable than those without. The heats of formation from crystalline SiO2, SiC, and C of SiOC PDCs without mixed bonding are close to zero and depend on the pyrolysis temperature. Solid state MAS NMR confirms the presence or absence of mixed bonding and further shows that, without mixed bonding, terminal hydroxyls are bound to some of the Si-O tetrahedra. This study indicates that mixed bonding, along with additional factors, such as the presence of terminal hydroxyl groups, contributes to the thermodynamic stability of SiOC PDCs.

Feature-Rich Geometric and Electronic Properties of Carbon Nanoscrolls.

How to form carbon nanoscrolls with non-uniform curvatures is worthy of a detailed investigation. The first-principles method is suitable for studying the combined effects due to the finite-size confinement, the edge-dependent interactions, the interlayer atomic interactions, the mechanical strains, and the magnetic configurations. The complex mechanisms can induce unusual essential properties, e.g., the optimal structures, magnetism, band gaps and energy dispersions. To reach a stable spiral profile, the requirements on the critical nanoribbon width and overlapping length will be thoroughly explored by evaluating the width-dependent scrolling energies. A comparison of formation energy between armchair and zigzag nanoscrolls is useful in understanding the experimental characterizations. The spin-up and spin-down distributions near the zigzag edges are examined for their magnetic environments. This accounts for the conservation or destruction of spin degeneracy. The various curved surfaces on a relaxed nanoscroll will create complicated multi-orbital hybridizations so that the low-lying energy dispersions and energy gaps are expected to be very sensitive to ribbon width, especially for those of armchair systems. Finally, the planar, curved, folded, and scrolled graphene nanoribbons are compared with one another to illustrate the geometry-induced diversity.

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.

Synthesis and Properties of Graphite Nitrate Cointercalation Compounds with Carboxylic Acid Esters

To expand the number of possible precursors of carbon nanoparticles, i.e., low-layer graphenes and nanoscrolls, binary and ternary graphite nitrate cointercalation compounds (GNCCs) with formic and acetic acid esters have been synthesized. X-ray powder diffraction data have demonstrated that the obtained GNCCs are stage II and IV intercalation compounds. It has been shown that the use of ethyl formate or an ethyl acetate/butyl acetate mixture as organic cointercalants leads to an increase in the height of the layer filled with intercalants as compared with graphite nitrate. Dispersions of carbon nanoparticles (low-layer graphenes and nanoscrolls) were obtained by sonication-assisted liquid-phase exfoliation of studied GNCCs in ethanol. The morphology of the obtained nanoparticles has been studied by transmission electron microscopy.

Emergence of carbon nanoscrolls from single walled carbon nanotubes: an oxidative route.

Carbon nanoscrolls (CNS), a one dimensional (1D) helical form of carbon, have received enormous attention recently due to their unique structure, superior properties and potential applications. In this work, radial merging of HiPCO single walled nanotube (SWNT) bundles and emergence of CNS are reported following a reflux action involving wet oxidation, HCl washing and annealing at 900 °C. We observe macroscopic quantities of graphene sheets (GS) in the post-treated sample and beautiful manifestation of curling and folding of the GS into CNS. Here, a simple solution based oxidative route for successful merging and exfoliation of SWNT bundles and subsequent formation of CNS are demonstrated and discussed in view of Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM) studies. Direct evidence of emergence of CNS from SWNTs via synthesis of GS through a simple oxidative method is reported for the first time.

Low reflectance of carbon nanotube and nanoscroll-based thin film coatings: a case study.

Research on carbon material-based thin films with low light reflectance has received significant attention for the development of high absorber coatings for stray light control applications. Herein, we report a method for the successful fabrication of stable thin films comprised of carbon nanotubes (CNTs) and nanoscrolls (CNS) on an aluminium (Al) substrate, which exhibited low reflectance of the order of 2–3% in the visible and near-infrared (NIR) spectral bands. Changes in the structural and chemical composition of pristine single-walled carbon nanotube (SWCNT) samples were analyzed after each processing step. Spectroscopy, microscopy and microstructural studies demonstrated emergence of CNS and multi-walled carbon nanotubes (MWCNTs) due to the sequential chemical processing of the sample. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) studies revealed the formation of CNS via curling and folding of graphene sheets. Microstructural investigations including SEM and atomic force microscopy (AFM) confirmed the presence of microcavities and pores on the surface of the film. These cavities and pores significantly contribute to the observed low reflectance value of CNTs, CNS compound films by trapping the incident light. Fundamental space environmental simulation tests (SEST) were performed on the coated films, that showed promising results with reflectance values almost unaltered in the visible and NIR spectral bands, demonstrating the durability of these films as potential candidates to be used in extreme space environmental conditions. This study describes the preparation, characterization, and testing of blended CNT and CNS coatings for low-light scattering applications.

N-Doped hierarchical porous carbon nanoscrolls towards efficient oxygen reduction reaction in Zn–air batteries via interior and exterior modifications

Etched EN-PCNS obtained using the combination of an in situ sacrificial template method and an NH3 etching method possesses a unique hierarchical porous morphology and controllable structure and composition, thus leading to an outstanding ORR performance in Zn–air batteries.

Preparation and photocatalytic N2/H2O to ammonia performance of cadmium sulfide/carbon nanoscrolls

Coal-based carbon nanoscrolls (CNS) were prepared through improved Hummers oxidation method using Xinjiang Wucaiwan coal as a carbon source, after removing impurities by acid treatment and graphitizing pretreatment. Then, the Cadmium sulfide (CdS) generated by the precipitation reaction of cadmium acetate and sodium sulfide was loaded on the coal-based CNS substrate in situ to prepare the composite photocatalyst CdS/CNS with different CdS content. The structure of the as-prepared CdS/CNS characterized, and the photocatalytic N2/H2O ammonia synthesis performance was studied. The results show that CNS is a kind of coal-based carbon nanomaterial evolved from graphene oxide (GO), yet it is more stable than GO and has a similar photoelectric property. Using it as a nano-catalyst substrate of the CdS can not only improve the agglomeration of CdS nanoparticles but also create structural defects in the composite catalyst that are favorable for photocatalytic reaction on the composite photocatalyst. It also provides more active sites for the photocatalytic reaction, and greatly increases the photoelectron transfer rate of the composite catalyst as well. Besides, CNS is a good catalyst carrier. The composite catalyst with CNS has a much better enhancement than pure CdS nanoparticles in both adsorption and activation of N2 and response to visible light. The 80%-CdS/CNS was used in the synthesis ammonia of photocatalysis N2/H2O. After 4 h reaction, the ammonia yield reached 1.337 mmol/L·g cat., which was about 3.29 times that of the ammonia synthesis using pure CdS under the same conditions.

Quantum Chemical Calculations of Carbon Nanoscroll Energy Rolled from Zigzag Graphene Nanoribbon

Using the semi-empirical quantum chemical PM3 method the energies of carbon nanoscrolls formed from flat zigzag graphene nanoribbons 46zGNR and 70zGNR are calculated. For this purpose a simple algorithm to define the Cartesian coordinates of the atoms of a carbon nanoscroll is proposed. The dependences of the energy of the nanoscrolls relative to the energy of the corresponding flat nanoribbon on the inner radius of nanoscroll obtained using both the quantum chemical calculations and the semi-classical analytical model shows the bistability of the system. This shows promise for nanoscroll-based nanoelectromechanical systems.

Structural configurations and Raman spectra of carbon nanoscrolls

Three types of carbon nanoscroll (CNS) structures that are formed when scrolling up graphene sheets are investigated using Raman spectroscopy and atomic force microscopy (AFM). The CNSs were produced from exfoliated monolayer graphene deposited on a Si chip by applying a droplet of isopropyl alcohol (IPA) solution. The three types of CNS are classified as single-elliptical-core, double-elliptical-core (both with large internal volumes) and collapsed ribbon-like, based on AFM surface profile measurements. We discuss the structure and formation of CNS with much larger hollow cores than is commonly assumed and relate this to the large effective 2D bending stiffness of graphene in the IPA solution. The large elliptical core structures show Raman spectra similar to those previously reported for CNS and indicate little interaction between the scrolled layers. The Raman spectra from ribbon-like structures show additional features that are similar to that of folded graphene. These new features can be related to layer breathing modes combined with some resonance enhancement at specific regions of the ribbon-like CNSs that are due to specific twist angles produced when the structure folds/collapses.

Friction properties of carbon nanoparticles (nanodiamond and nanoscroll) confined between DLC and a-SiO2 surfaces

Friction properties of carbon nanodiamond (CND) and nanoscroll (CNS formed from graphene patch wrapping around nanodiamond) were studied by nonequilibrium molecular dynamic simulation of sliding diamond-like carbon (DLC) over the nanoparticles supported by amorphous silica (a-SiO2) slabs. CNS reduces friction coefficient (COF) by 72% relative to CND and superlubricity (COF ≤ 0.01) is enabled by CNS, which agrees well with experimental observations. Due to the wrapping graphene patch, the DLC-CNS contact area is smaller than the DLC-CND contact area and the CNS motion is repressed. Contrary to the rolling motion of ball bearings at the macroscale, the repressed motion of nanoparticles reduces the system friction dissipation. These make CNS a more effective solid lubricant compared with CND.