One-dimensional Carbon Nanostructures Research Articles

Unravelling the formation of carbyne nanocrystals from graphene nanoconstrictions through the hydrothermal treatment of agro-industrial waste molasses.

The delicate synthesis of one-dimensional (1D) carbon nanostructures from two-dimensional (2D) graphene moiré layers holds tremendous interest in materials science owing to its unique physiochemical properties exhibited during the formation of hybrid configurations with sp-sp2 hybridization. However, the controlled synthesis of such hybrid sp-sp2 configurations remains highly challenging. Therefore, we employed a simple hydrothermal technique using agro-industrial waste as the carbon source to synthesize 1D carbyne nanocrystals from the nanoconstricted zones of 2D graphene moiré layers. By employing suite of characterization techniques, we delineated the mechanism of carbyne nanocrystal formation, wherein the origin of carbyne nanochains was deciphered from graphene intermediates due to the presence of a hydrothermally cut nanoconstriction regime engendered over well-oriented graphene moiré patterns. The autogenous hydrothermal pressurization of agro-industrial waste under controlled conditions led to the generation of epoxy-rich graphene intermediates, which concomitantly gave rise to carbyne nanocrystal formation in oriented moiré layers with nanogaps. The unique growth of carbyne nanocrystals over a few layers of holey graphene exhibits excellent paramagnetic properties, the predominant localization of electrons and interfacial polarization effects. Further, we extended the application of the as-synthesized carbyne product (Cp) for real-time electrochemical-based toxic metal (As3+) sensing in groundwater samples (from riverbanks), which depicted superior sensitivity (0.22 mA μM-1) even at extremely lower concentrations (0.0001 μM), corroborating the impedance spectroscopy analysis.

Simulation-aided studies on the superior thermoelectric performance of printable PBDTT-FTTE/SWCNT composites

Quasi one-dimensional (1D) carbon nanostructures hybridized with π-conjugated polymeric systems are vastly explored for their unique heat/carrier transport beneficial for thermoelectric (TE) applications. We present the TE response of all-organic composites fabricated with poly[4,8-bis(5-(2-ethylyhexyl)thiophene-2-yl)benzo[1,2-b; 4,5-b']dithiophene-2,6-diyl-alt-(4-(2-ethylhexyl)3-fluorothieno[3,4-b']thiophene-)-2-carboxylate-2-6-diyl)] (PBDTT-FTTE) and single-walled carbon nanotube (SWCNT). SWCNTs form strong π-π interfacial interactions with the polymer, and their TE performance is improved through p-doping with ferric chloride (FeCl3). Investigation of the electrical conductivity (σ) and Seebeck coefficient (α) reveals a characteristic mechanism arising from low-energy carrier filtering and Fermi-level pinning. DIGIMAT-MF© material modeling platform simulates σ and thermal conductivity (κ) and indicates a CNT aspect ratio distribution in the system. The doped composite with 55 wt% SWCNT exhibits the maximum ZT value of 0.044 at 303 K using the simulated κ value. A flexible TE generator (TEG) consisting of 21 legs is dispenser printed that produces ∼32.7 nW power output with a 65 K temperature gradient across 15 kΩ load resistance. COMSOL Multiphysics® simulation is used to optimize TEG design for maximum extractable output power.

Carbon Nanostructures-Transition Metal Oxide Hybrid As Bifunctional Electrocatalyst

The keen to replace coal and petroleum-based energy with renewable and environment friendly resources has persuaded the research in energy conversion and storage devices like metal-air batteries, fuel cell and electrolyzers. Oxygen electrochemistry that includes oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) are sluggish reactions. RuO2/IrO2 and Pt-C are promising candidates in terms of the catalytic performance for OER and ORR, respectively. However, stability and the cost hinder its usage for large scale commercial applications. Therefore, rational designing of electrocatalyst that can overcome these sluggish reactions accounting their economic factor is important. Moreover, designing bifunctional catalyst remains a challenging issue till now. Carbon based materials have been extensively known for ORR whereas transition metal oxides show promising OER. 1 2 In this regard, we have synthesized a hybrid consisting of one-dimensional carbon nanostructures supported on Co-Ni oxide that shows efficient OER and ORR activity with low overpotential (OER), E1/2 (ORR), excellent stability and durability. The low Tafel slope for both OER and ORR reveals favorable reaction kinetics. Importantly, the hybrid offers ∆E (Ej=10 -E½) of 0.80 V that shows the promising bifunctional behavior. The overall study indicates that the hybrid catalyst is as potential candidate for OER/ORR and hence, expected to serve the energy storage device like metal-air batteries. References (1) Devi, H. R.; Nandan, R.; Nanda, K. K. Mechanistic Investigation into Efficient Water Oxidation by Co-Ni-Based Hybrid Oxide-Hydroxide Flowers. ACS Appl. Mater. Interfaces 2020, 12 (12), 13888–13895.(2) Nandan, R.; Devi, H. R.; Kumar, R.; Singh, A. K.; Srivastava, C.; Nanda, K. K. Inner Sphere Electron Transfer Promotion on Homogeneously Dispersed Fe-N XCenters for Energy-Efficient Oxygen Reduction Reaction. ACS Appl. Mater. Interfaces 2020, 12 (32), 36026–36039.

Molecular Dynamics Simulation of Chiral Carbon Nanothread Bundles for Nanofiber Applications

Carbon nanofibers as constructed from various one-dimensional carbon nanostructure, such as sp3 diamond nanowire, sp2 carbon nanotubes, and carbyne, have received enormous interest from both scientific and engineering communities. The newly synthesized nanostructure carbon nanothreads (C_NTH) show superior properties and make them ideal building blocks for high-performance carbon nanofibers. This work systematically investigates the torsional properties of C_NTH bundles through high-throughput large-scale molecular dynamics simulations. Our results show that the torsional behavior of C_NTH bundles depends strongly on the loading direction. By adjusting the enantiomer ratios, we can effectively tune the mechanical properties of the bundle structure, including the strain energy density, elastic limit, and torsional rigidity. Benefiting from their rich structural varieties, this work suggests that carbon nanothreads are promising candidates for the next-generation high-performance carbon nanofiber.

Role of Nitrogen on the Mechanical Properties of the Novel Carbon Nitride Nanothreads

Carbon nanothread (C-NTH) is a new ultrathin one-dimensional sp3 carbon nanostructure, which exhibits promising applications in novel carbon nanofibers and nanocomposites. Recently, researchers have successfully developed a new alternative structure - ultrathin carbon nitride nanothread (CN-NTH). In this work, we investigate the mechanical properties of CN-NTHs through large-scale molecular dynamics simulations. Comparing with their C-NTH counterparts, CN-NTHs are found to exhibit a higher tensile and bending stiffness. In particular, because of the bond redistribution, the CN-NTHs in the polymer I group and tube (3,0) group are found to possess a higher failure strain than their C-NTH counterparts. However, the CN-NTH in the polytwistane group has a smaller failure strain compared with the pristine C-NTH. According to the atomic configurations, the presence of nitrogen atoms always leads to stress/strain concentrations for the nanothreads under tensile deformation. This study provides a comprehensive understanding of the mechanical properties of CN-NTHs, which should shed light on their potential applications such as fibers or reinforcements for nanocomposites.

Development of humidity sensor using modified curved MWCNT based thin film with DFT calculations

One-dimensional carbon nanostructures e.g. Carbon nanotubes (CNTs) possess outstanding physical properties owing to their unique structure and atomic arrangement. High electrical conductivity, highly exposed surface area and stability of these carbon nanostructures introduce them as the leading choice of nanomaterials for a number of electrical and industrial applications like humidity and gas sensing. The conductance or capacitance of CNTs varies greatly with the adsorption-desorption of molecules such as hydroxyl (OH−) ions. In this paper, we report the preparation of carbon nanotubes based thin film using a CVD technique which has been characterized by using Scanning Electron Microscopy (SEM), UV–vis microscopy and X-ray diffraction technique. The characterized film was investigated as a humidity sensor. In the experimental part, the variations in the impedance of film were observed by Impedance Analyzer 6440 B on varying the humidity levels. In the theoretical part, we have simulated the CNTs using Ab initio density functional theory (DFT) calculations to investigate the formation of endohedral complexes among CNTs and OH− groups. The binding energy, dipole moment, electronegativity and HOMO-LUMO gaps were monitored by increasing the hydroxyl group levels, which results in its better use in developing a robust and cost-effective humidity sensor.

Structural parameters, electronic properties, and band gaps of a single walled carbon nanotube: A pz orbital tight binding study

Single walled carbon nanotube (SWCNT), an emerging one-dimensional carbon nanostructure, have several unique attributes and amazing properties that offers a great potential for interconnects, nanoelectronic and optoelectronic devices. For the first time, the pz orbital tight binding study on structural parameters, electronic properties, and band gaps of a SWCNT have been presented and analyzed in this paper. The analytical values of different parameters regarding the overall unit cell and molecular structure of a SWCNT have been verified using the simulation approach, therefore, proved the validation of both the simulation as well as analytical values. It has been observed that the total number of unit cells, carbon atoms, and hexagons within the overall unit cell and molecular structure of a SWCNT at different chirality values and lengths obtained using the simulation matches with the analytical values. Further, the metallic and semiconducting properties of a SWCNT can be investigated with the help of different simulated electronic band structures obtained for different chirality combinations. First, it has been found that all armchair SWCNTs are metallic with a very small constant band gap of 10.88 meV whereas the zigzag SWCNTs show metallic as well as semiconductor behavior with zero and larger than zero band gap values. Second, it has been observed that the total number of subbands in each electronic band structure of a SWCNT (both armchair and zigzag) is chirality dependent and equal to the total number of carbon atoms present in their overall unit cell structure. Furthermore, the reported band gap values have been compared with the already published calculation as well as experimental values which show excellent agreement between them. Finally, it has been observed that the metallic SWCNTs are best suited for interconnects and the semiconducting SWCNTs are best suited for novel channel materials of a field effect transistor.

Carbon hollow nanobubbles on porous carbon nanofibers: An ideal host for high-performance sodium-sulfur batteries and hydrogen storage

One-dimensional (1D) carbon nanostructures have been intensively investigated because of their intriguing features and great potential for practical application in various fields. This paper reports the controllable fabrication of carbon hollow nanobubbles on porous carbon nanofibers (CHNBs@PCNFs) through a general electrospinning strategy, with metal azides serving as both a bubbling and a porogen reagent. The strong repulsive forces resulting from the intense release of N2 from the decomposition of metal azides upon carbonization leads to the uniform formation of porous carbon nanofibers (PCNFs), which could be facile tuned by heating rates and the amount of the bubbling reagent, simultaneously constructed with carbon hollow nanobubbles (CHNBs) on the surface. Density functional theory calculations reveal the strong interactions between terminal Na atoms in sodium polysulfides and N and O atoms doped into CHNBs@PCNFs, which could effectively alleviate the shuttle effect of Na-S batteries via adsorbing and trapping polysulfides. With strong adsorption capability of sodium polysulfides and high electrical conductivity, these CHNBs@PCNFs are demonstrated to be an ideal sulfur host in room-temperature sodium-sulfur batteries, which delivers a high reversible capacity of 256 mA h g−1 (specific energy density 384 W h kg−1) with a low decay rate of 0.044% per cycle at 2 C-rate. When CHNBs@PCNFs used as functional supports for MgH2 nanoparticles, a significantly enhanced hydrogen storage performance was achieved. The present work represents a critically important step in advancing the electrospinning technique for generating 1D carbon nanostructures in a facile and universal manner.

Functionalized diamond nanothreads from benzene derivatives.

Diamond nanothreads (DNTs) are fully sp3-bonded one-dimensional carbon nanostructures, synthesized recently through compression of crystalline benzene. They possess outstanding mechanical strength, suitable for the development of novel nanostructured reinforced materials. In this article, we use density functional theory calculations to investigate the feasibility and physical properties of functionalized DNTs. We show that the stacking and covalent bonding of benzene derivative molecules (toluene, aniline, phenol and fluorobenzene) may lead to stable configurations analogous to benzene-derived DNTs, with functional groups (-CH3, -NH2, -OH, -F) covalently attached to the surface. The same principle was also applied to pyridine, an aromatic heterocyclic compound, resulting in DNTs containing N heteroatoms within the sp3 C-C chain. We show that the mechanical properties remain practically unaltered compared to the original material, and that the electronic properties can be tuned upon functionalization. The presence of polar functional groups on DNT surfaces are expected to affect their compatibility with other materials and solvents, enabling the development of novel processes and technological applications using DNTs.

The morphological effect on electronic structure and electrical transport properties of one-dimensional carbon nanostructures

This work reveals a relationship of morphological structure, electronic structure and electrical transport properties in carbon nanomaterials.

First-principles calculation of the mechanical properties of diamond nanothreads

The synthesis of novel one-dimensional carbon nanostructures named diamond nanothreads (DNT) has been recently reported, and subsequent studies employing molecular dynamics (MD) simulations demonstrated that they possess remarkable mechanical properties. In this paper we present the results of Density Functional Theory calculations of the mechanical properties for several DNT configurations, confirming that they indeed exhibit a high ideal strength (as high as 15.7 nN or 2.6 × 107 N m/kg) and stiffness (as high as 168 nN or 2.8 × 108 N m/kg), similarly to other carbon nanostructures. We compare these results with previously reported and additional MD calculations, and show that traditional interatomic potentials predict these properties with deviations up to ∼50%. A detailed analysis of the dependence of atomic structure on strain shows the reasons for these discrepancies. We also show that the most known DNT configuration (the (3,0) sp3-nanotube) exhibits a negative radial Poisson ratio.

In Situ Synthesis and Characterization of Ge Embedded Electrospun Carbon Nanostructures as High Performance Anode Material for Lithium-Ion Batteries.

While active materials based on germanium (Ge) are considered as a promising alternative anodic electrode due to their relatively high reversible capacity and excellent lithium-ion diffusivity, the quite unstable structural/electrochemical stability and severe volume expansion or pulverization problems of Ge electrodes remain a considerable challenge in lithium ion batteries (LIBs). Here, we present the development of Ge embedded in one-dimensional carbon nanostructures (Ge/CNs) synthesized by the modified in situ electrospinning technique using a mixed electrospun solution consisting of a Ge precursor as an active material source and polyacrylonitrile (PAN) as a carbon source. The as-prepared Ge/CNs exhibit superior lithium ion behavior properties, i.e., highly reversible specific capacity, rate performance, Li ion diffusion coefficient, and superior cyclic stability (capacity retention: 85% at 200 mA g(-1)) during Li alloying/dealloying processes. These properties are due to the high electrical conductivity and unique structures containing well-embedded Ge nanoparticles (NPs) and a one-dimensional carbon nanostructure as a buffer medium, which is related to the volume expansion of Ge NPs. Thus, it is expected that the Ge/CNs can be utilized as a promising alternative anodic material in LIBs.

Growth of hybrid carbon nanostructures on iron-decorated ZnO nanorods

A novel carbon-based nanostructured material, which includes carbon nanotubes (CNTs), porous carbon, nanostructured ZnO and Fe nanoparticles, has been synthetized using catalytic chemical vapour deposition (CVD) of acetylene on vertically aligned ZnO nanorods (NRs). The deposition of Fe before the CVD process induces the presence of dense CNTs in addition to the variety of nanostructures already observed on the process done on the bare NRs, which range from amorphous graphitic carbon up to nanostructured dendritic carbon films, where the NRs are partially or completely etched. The combination of scanning electron microscopy and in situ photoemission spectroscopy indicate that Fe enhances the ZnO etching, and that the CNT synthesis is favoured by the reduced Fe mobility due to the strong interaction between Fe and the NRs, and to the presence of many defects, formed during the CVD process. Our results demonstrate that the resulting new hybrid shows a higher sensitivity to ammonia gas at ambient conditions (∼60 ppb) than the carbon nanostructures obtained without the aid of Fe, the bare ZnO NRs, or other one-dimensional carbon nanostructures, making this system of potential interest for environmental ammonia monitoring. Finally, in view of the possible application in nanoscale optoelectronics, the photoexcited carrier behaviour in these hybrid systems has been characterized by time-resolved reflectivity measurements.

Reverse Kebab Structure Formed inside Carbon Nanofibers via Nanochannel Flow

The morphology of polymers inside a confined space has raised great interest in recent years. However, polymer crystallization within a one-dimensional carbon nanostructure is challenging due to the difficulty of polar solvents carrying polymers to enter a nonpolar graphitic nanotube in bulk solution at normal temperature and pressure. Here we describe a method whereby nylon-11 was crystallized and periodically distributed on the individual graphitic nanocone structure within hollow carbon nanofibers (CNF). Differential scanning calorimetry and X-ray diffraction indicate that the nylon polymer is in the crystalline phase. A mechanism is suggested for the initiation of nanochannel flow in a bulk solvent as a prerequisite condition to achieve interior polymer crystallization. Selective etching of polymer crystals on the outer wall of CNF indicates that both surface tension and viscosity affect the flow within the CNF. This approach provides an opportunity for the interior functionalization of carbon nanotubes and nanofibers for applications in the biomedical, energy, and related fields.

Examining Carbon Nanofibers: Properties, growth, and applications

One-dimensional carbon ?nanostructures have been known and fabricated for more than a hundred years and were originally referred to as filamentous carbon,carbon filaments, or carbon whiskers. However, it was only during the 1990s and 2000s with the demonstration of carbon nanotubes (CNTs)and the introduction of catalytic plasma-enhanced chemical vapor deposition (PECVD) that one-dimensional carbon nanostructures emerged as a promising solution for a large variety of applications. In this article, carbon nanofibers (CNFs), a particular type of one-dimensional carbon with unique properties, are described, their growth is discussed, and their main applications are presented.

Direct growth of carbon nanofibers on carbon-based substrates as integrated gas diffusion and catalyst layer for polymer electrolyte fuel cells

One-dimensional carbon nanostructures are considered promising for application as catalyst support in polymer electrolyte fuel cells, replacing the most widely used carbon black, due to their physico-chemical properties and high surface area. Different morphologies of carbon nanofibers, by varying the graphene layers orientation with respect to the fibre axis, exhibit different amount of available open edges that can act as anchorage site for catalyst nanoparticles. CNF are grown on graphite paper by a controlled plasma enhanced chemical vapour deposition and then used as substrates for Pt electrodeposition. The CNF direct growth on carbon paper allows having single layer electrodes with both diffusive and catalytic layer function. Moreover, the replacement of conventional ink deposition methods with electrodeposition for platinum dispersion, allows greatly reducing the catalyst load, increasing at the same time its utilization and performance. The innovative electrodes are characterized by field emission gun scanning electron microscopy and X-ray photoelectron spectroscopy to assess the morphological properties, and by cyclic voltammetry in H2SO4 and H2SO4 + CH3OH to determine the electrocatalytic activity and long term stability. The comparison with an electrode made of conventionally deposited Pt catalyst by ink method on commercial carbon black shows better performance for the developed Pt/CNF electrodes.

Nitrogen-Doped Hierarchical Porous Carbon Nanowhisker Ensembles on Carbon Nanofiber for High-Performance Supercapacitors

Controlled synthesis of carbon nanomaterials with particular shape, composition, architecture, and doping is very important, yet still a great challenge, for enhancing supercapacitor performance with high energy and power densities and long lifetime. Herein, we demonstrate an interesting process combining surfactantless and templateless wet chemical and post-high-temperature carbonization strategies for obtaining a new class of nitrogen-doped hierarchical porous carbon nanowhisker ensembles supported on carbon nanofibers (NHCNs) with tunable micropores and a nitrogen-doping level for high-performance supercapacitors. Under the optimal pore size and nitrogen doping controlled by carbonization at different temperatures, the NHCNs (NHCNs-750) carbonized at 750 °C shows an optimal specific capacitance of 210.1 F g–1 at 5 mV s–1, which is much higher than other one-dimensional carbon nanostructures (e.g., pure carbon nanofibers (2.6 F g–1) and carbon nanotubes (10.6 F g–1) at 5 mVs–1). NHCNs-750 also showed go...

Synthesis of one-dimensional carbon nanostructures and their application as anode materials in lithium ion batteries

An efficient synthesis of carbon nanofibers by pyrolysis of as-prepared polypyrrole nanowires was reported. Under the subsequent KOH activation, a significant morphology variation was detected and the obtained sample took on a ribbon-like structure. The morphology and structure of the carbon nanofibers and carbon nanoribbons were characterized. When the as-prepared one-dimensional carbon nanostructures were used as anode materials in lithium ion batteries, both of them exhibited superior cyclical stability and good rate properties. After 50 cycles, the reversible capacity of carbon nanofibers electrode maintained 530 mA·h/g. Concerning carbon nanoribbons, the reversible capacity is always larger than 850 mA·h/g and the reversible capacity retention after 23 cycles is 86%.

Controlled synthesis of carbon nanostructures using aligned ZnO nanorods as templates

By combining in situ X-ray photoemission spectroscopy, ex situ high resolution transmission electron microscopy, scanning electron microscopy, and Raman spectroscopy, we show that chemical vapor deposition (CVD) on vertically aligned ZnO nanorods can synthesize different carbon nanostructures (CNs), whose morphology is driven by the ZnO nanorods and whose dimensions and structures change as a function of the process temperature. The CNs range from amorphous carbon cups, completely covering the nanorods, to high density one-dimensional carbon nano-dendrites (CNDs), which start to appear like short hairs on the ZnO nanorods. The nanorods are partially etched when the process is done at 630–800°C, while they are completely etched at temperatures higher than 800°C. In the latter case, CNDs emerge from a porous carbon sponge formed at the substrate interface but they are preferentially aligned along the location of the pristine ZnO nanorods. When used as a chemiresisitor the CND–ZnO structures have a higher sensitivity to ammonia compared to chemiresistors made by bare ZnO nanorods, to other one-dimensional CNs, like carbon nanotubes or other metal/metal-oxides hybrid CNs.

Role of Carbon Nanotubes in Dye-Sensitized TiO2-Based Solar Cells

Incorporation of low-dimensional carbon nanostructures such as carbon nanotubes (CNTs) and graphene sheets into the semiconductor electrodes is a common approach to improve the charge collection and photovoltaic performance of dye-sensitized solar cells. In this work, we clarify the role of CNTs in the semiconductor electrodes by investigating and comparing the electronic process in the dye-sensitized TiO2-based photovoltaic devices. The results show that the formed CNT–TiO2 Schottky junction plays a crucial role in the photovoltaic characteristics. According to the thermionic emission theory, the variation of the photocurrent over the voltage of the cells strongly depends on the height of the Schottky barrier. When the output voltage is low, the intrinsic one-dimensional carbon nanostructures can facilitate electron transport. With the voltage of the cell increasing, the energy dissipation on the Schottky junction increases dramatically and CNTs gradually lose the role of electron transport channels. At ...