1D Carbon Nanostructures Research Articles

Exploring New Carbon Allotropes and Nanographenes on Surfaces

The quest for planar sp2-hybridized carbon allotropes other than graphene has stimulated substantial research efforts because of their predicted unique mechanical, electronic, and transport properties. However, the syntheses of these nonbenzenoid networks remain challenging due to the lack of reliable protocols for generating nonhexagonal rings. We have developed various on-surface synthesis strategies by which straight polymer chains are linked to form the nonbenzenoid carbon networks. In this way, we synthesized biphenylene network, a new carbon allotrope with 4-6-8-membered rings, which is metallic already at very small dimensions. Similarly, we generated phagraphene nanoribbons, which are based on 5-6-7-membered rings.Acenes are another interesting class of carbon materials that have fascinated chemists and physicists due to their potential for use in organic electronic applications. We show the synthesis of tridecacene (13ac) and pentadecacene (15ac), the longest acenes known to date, via multistep single-molecule manipulation of suitable precursor molecules on Au(111). We find antiferromagnetic open-shell ground state electron configurations for both acenes. 15ac shows a low-bias spin-excitation feature, indicating a singlet-triplet gap of around 124 meV. Investigation of 15ac complexes with up to 6 gold atoms suggest considerable multiradical contributions to the electronic ground state of 15ac.Altering the electronic and magnetic properties of carbon-based nanomaterials can also be achieved by doping with heteroatoms. We present an access to a variety of nitrogen-containing 0D and 1D carbon nanostructures including planar and curved cycloarenes with different cavities as well as N-doped graphene nanoribbons.

Nanoimprint Lithography for Next-Generation Carbon Nanotube-Based Devices.

This research reports the development of 3D carbon nanostructures that can provide unique capabilities for manufacturing carbon nanotube (CNT) electronic components, electrochemical probes, biosensors, and tissue scaffolds. The shaped CNT arrays were grown on patterned catalytic substrate by chemical vapor deposition (CVD) method. The new fabrication process for catalyst patterning based on combination of nanoimprint lithography (NIL), magnetron sputtering, and reactive etching techniques was studied. The optimal process parameters for each technique were evaluated. The catalyst was made by deposition of Fe and Co nanoparticles over an alumina support layer on a Si/SiO2 substrate. The metal particles were deposited using direct current (DC) magnetron sputtering technique, with a particle ranging from 6 nm to 12 nm and density from 70 to 1000 particles/micron. The Alumina layer was deposited by radio frequency (RF) and reactive pulsed DC sputtering, and the effect of sputtering parameters on surface roughness was studied. The pattern was developed by thermal NIL using Si master-molds with PMMA and NRX1025 polymers as thermal resists. Catalyst patterns of lines, dots, and holes ranging from 70 nm to 500 nm were produced and characterized by scanning electron microscopy (SEM) and atomic force microscopy (AFM). Vertically aligned CNTs were successfully grown on patterned catalyst and their quality was evaluated by SEM and micro-Raman. The results confirm that the new fabrication process has the ability to control the size and shape of CNT arrays with superior quality.

Density functional theory and quantum mechanics studies of 2D carbon nanostructures (graphene and graphene oxide) for Lenalidomide anticancer drug delivery

This research was carried out to examine nanomaterials for the delivery of a Lenalidomide (LND) anticancer agent. LND has primarily been used to treat cancer patients. To this point, the drug distribution of LND was evaluated in this study using two typical nanostructure models, graphene (G) and graphene oxide (GOx). To obtain the necessary findings of singular and interacting models, density functional theory (DFT), density functional tight binding theory (DFTB+), Monte Carlo (MC), and Molecular Dynamic (MD) calculations were conducted. For the studied model systems, stabilized structures and associated electronic features were assessed. Formation possibilities for both LND@G and LND@GOx complex models were discovered, and the associated complex interactions were studied using features of the quantum theory of atoms in the molecule (QTAIM). Variations in the levels of frontier molecular orbitals also suggested the interaction of LND with G and GOxstructures. As a result, the obtained results showed that the studied complex models of LND@G and LND@GOx were suitable for carrying out the desired drug delivery processes using acceptable nano-based surfaces as carriers.

Continuous modelling of single layer 2D carbon nanostructures based on a modified Cauchy–Born rule

AbstractGraphene is the thinnest known structure. It consists of a single layer of carbon atoms and has unique mechanical properties. The carbon atoms form bonds with neighbouring atoms that can be described by interatomic potentials. A simulation of molecular mechanical processes can be performed by applying the formalism of the finite element method to the interatomic potentials. Neglecting local effects, a continuum formulation is an efficient alternative to a discrete model. The continuum formulation requires a connection between the discrete atomic lattice and the continuum. One way of doing this is to use the Cauchy–Born rule. This paper reviews the extensions of the Cauchy–Born rule, in particular, the exponential Cauchy–Born rule, and adds an alternative approach. It is shown that all contributions dealing with the exponential Cauchy–Born rule inevitably lead to shell models with Kirchhoff–Love kinematics. The approach presented here instead uses a shell model with Reissner–Mindlin kinematics, which has the major advantage of a much simpler mesh generation and a simpler application of the boundary condition.

Tunable growth of one-dimensional graphitic materials: graphene nanoribbons, carbon nanotubes, and nanoribbon/nanotube junctions

Graphene nanoribbons (GNRs) and carbon nanotubes (CNTs), two representative one-dimensional (1D) graphitic materials, have attracted tremendous research interests due to their promising applications for future high-performance nanoelectronics. Although various methods have been developed for fabrication of GNRs or CNTs, a unified method allowing controllable synthesis of both of them, as well as their heterojunctions, which could largely benefit their nano-electronic applications, is still lacking. Here, we report on a generic growth of 1D carbon using nanoparticles catalyzed chemical vapor deposition (CVD) on atomically flat hexagonal boron nitride (h-BN) substrates. Relative ratio of the yielded GNRs and CNTs is able to be arbitrarily tuned by varying the growth temperature or feeding gas pressures. The tunability of the generic growth is quantitatively explained by a competing nucleation theory: nucleation into either GNRs or CNTs by the catalysts is determined by the free energy of their formation, which is controlled by the growth conditions. Under the guidance of the theory, we further realized growth of GNR/CNT intramolecular junctions through changing H2 partial pressure during a single growth process. Our study provides not only a universal and controllable method for growing 1D carbon nanostructures, but also a deep understanding of their growth mechanism, which would largely benefit future carbon-based electronics and optoelectronics.

Thermal Transport Study in a Strained Carbon Nanotube and Graphene Junction Using Phonon Wavepacket Analysis

This study investigates single-mode phonon scattering from a junction structure consisting of a (6,6) single-walled carbon nanotube (SWCNT) and graphene, subject to mechanical deformation, using phonon wavepacket analysis. Results show that longitudinal acoustic (LA) and transverse acoustic (TA) phonons at low frequencies are transmitted more effectively through the SWCNT–graphene junction when the junction is deformed. As low-frequency phonons in LA and TA modes are major energy carriers, it is expected that thermal transport across the SWCNT–graphene junction will be more efficient when the junction is deformed. Interfacial thermal resistance across the SWCNT-graphene junction was calculated using reverse nonequilibrium molecular dynamics (RNEMD). The RNEMD results show that the interfacial thermal resistance decreases when the structure is elongated, deforming the junction between the SWCNT and graphene. However, there was no notable difference in the transmission of twisting (TW) and flexural (FO) phonons when the junction was deformed. The study also showed that the transmission of phonon energy through the SWCNT–graphene junction has a slight dependence on the group velocity of phonons, with phonons having higher group velocities transmitting the junction more effectively. The findings of this research will play a significant role in advancing the development of futuristic electronics by providing a tool for developing 3D carbon nanostructures with high thermal performance under mechanical deformation.

Electronic properties and carrier mobilities of nanocarbons formed by non-benzoidal building blocks.

Exotic 1D and 2D carbon nanostructures have been grown in the laboratory in the last few years by means of surface-assisted chemical routes. In these processes, the strategical choice of a molecular precursor plays a dominant role in the determination of the synthesized nanocarbon. Further variations of these techniques are able to produce non-benzoidal carbon quantum-dots (QDs). Considering this experimental scenario as motivation, we propose a series of nanoribbon systems based on concatenating recently synthesized carbon QDs containing pentagonal, hexagonal, and heptagonal rings. We use density functional theory (DFT) simulations to reveal their properties can range from metallic to semiconducting depending on the concatenation hierarchy used to form the nanoribbons. This DFT implementation is based on a LCAO approach to describe valence wavefunctions and most of the simulations employ the PBE-GGA functional. Since this functional is known to underestimate band gaps, we also use the B3LYP functional in a plane-wave DFT approach for a selected case for comparison purposes. These systems show a different gap versus width relationship compared to conventional graphene nanoribbons setups and a particular set of carrier mobility values. We further discuss the interplay between the QD's frontier states and the electronic properties of the nanoribbons in light of their structural details.

Temperature-modulated synthesis of vertically oriented atomic bilayer graphene nanowalls grown on stainless steel by inductively coupled plasma chemical vapour deposition

It is now clear that growing flat graphene nanostructures from the gas phase on planar substrates is possible. One of the keys to success —particularly in producing a very large specific surface in a reduced space— is the use of 3D carbon nanostructures (i.e., vertical graphene nanowalls, VGNWs) over a planar substrate as a growth template for the deposition of electrochemically active materials (as, for example, transition metal oxides (TMO)). Vertical graphene nanowalls, also known as petal-like, vertical graphene flakes or vertical graphene, can achieve a very large specific surface area of 1100 m2/g, which is comparable to or greater than that of carbon nanotubes —the reference material for its use in high-performance supercapacitors or in other energy-related applications requiring a large active surface area. Vertical graphene nanowalls also exhibit high vertical and in-plane electrical conductivity when grown on metal electrodes, which benefits their use in electrochemical applications. Here, we focus on the growth of VGNWs on flexible stainless-steel substrates (SS310), in principle suitable for applications to electrodes of electrochemical systems (batteries, supercapacitors, catalysts), by inductively coupled plasma chemical vapour deposition (ICP-CVD), from methane as a carbon precursor, in a wide range of temperatures (575 to 900 °C). We will discuss the effect of growth temperature on morphological and structural characteristics of VGNWs based on the results of Raman spectroscopy and field emission scanning electron microscopy (FE-SEM) analysis. Because the nanostructures of graphene nanowalls reported to date are, for the most part, based on multi-layered graphene, here we seek to highlight the effect of temperature on the number of atomic layers of VGNW. In the 700–750 °C range, and under the plasma conditions explored, vertical graphene nanowalls are bilayer, which is foreseen to directly affect the magnitude of the VGNW specific surface.

Design of Hierarchical Oxide‐Carbon Nanostructures for Trifunctional Electrocatalytic Applications

AbstractThe rational design of efficient trifunctional catalysts for oxygen evolution reaction (OER), oxygen reduction reaction (ORR), and hydrogen evolution reaction (HER) is of significant importance for metal–air batteries and electrolyzers. Herein, a hierarchical carbon architecture that comprises of 1D tubes and 2D sheets supported on Ni–Co oxide is synthesized. The 1D–2D carbon nanostructures further support homogeneously dispersed Co/Ni–Nx centers, NiCo and its oxide nanoparticles that are beneficial for ORR, HER, and OER, respectively. The hierarchical nanostructures offer highly exposed surface that enables the maximum utility of active sites for different reactions and also provide a single platform that can be used as OER–ORR and OER‐HER bifunctional catalyst for metal– air batteries and electrolyzers, respectively. The catalyst displays a low ΔE (EJ(OER) = 10 − E½(ORR)) of 0.846 V for bifunctional OER–ORR and low potential of 1.54 V at 10 mA cm−2 for overall water splitting with appreciable durability for 40 h. Overall, the nanostructures exhibit remarkable activity and are durable for OER, ORR, and HER. Moreover, the study offers a pathway to expand the functionality of the non‐noble electrocatalyst and simultaneously offers a platform to prove that preferential active sites exist for different reactions.

A Quantitative Chemical Method for Determining the Surface Concentration of Stone-Wales Defects for 1D and 2D Carbon Nanomaterials.

A quantitative method is proposed to determine Stone–Wales defects for 1D and 2D carbon nanostructures. The technique is based on the diene synthesis reaction (Diels–Alder reaction). The proposed method was used to determine Stone–Wales defects in the few-layer graphene (FLG) nanostructures synthesized by the self-propagating high-temperature synthesis (SHS) process in reduced graphene oxide (rGO) synthesized based on the method of Hammers and in the single-walled carbon nanotubes (SWCNT) TUBAL trademark, Russia. Our research has shown that the structure of FLG is free of Stone–Wales defects, while the surface concentration of Stone–Wales defects in TUBAL carbon nanotubes is 1.1 × 10−5 mol/m2 and 3.6 × 10−5 mol/m2 for rGO.

Preparation and Electrocatalytic Activity of a Cobalt Mixed Nitrogen 3D Carbon Nanostructure @ Carbon Felt toward an All-Vanadium Redox Flow Battery

All-vanadium redox flow batteries (VRFBs), with good operation flexibility and scalability, have been regarded as one of the most competitive substitutes for large-scale energy storage. However, because of the low electrochemical activities of traditional electrodes such as carbon felt and graphite felt, they will impede the interfacial charge transfer processes and decrease the efficiencies of VRFBs. In this work, Co-MOF (ZIF-67) was prepared as a precursor, and a cobalt mixed nitrogen 3D carbon nanostructure and carbon felt (Co-CN@CF) was prepared by chemical reaction and used in VRFBs as electrodes. With the unique structure and high efficiency catalyst on the carbon felt, the Co-CN@CF exhibited excellent electrochemical activity toward the VO2+/VO2+ redox couple in the VRFB, with an average cell voltage efficiency (VE) of 86% and an energy efficiency (EE) of 82% at 80 mA cm−2, which was increased by more than 10% compared with the traditional carbon felt. VRFBs with a Co-CN@CF electrode also showed much better long-term stability (over 1000 cycles) compared with the battery with a pristine CF electrode.

HFIP-functionalized 3D carbon nanostructure as chemiresistive nerve agents sensors under visible light

A new generation of reliable, sustainable and low power consumption sensors of chemical warfare agents (CWAs) is critically needed for homeland and manufacturing areas security. Due to large active surface, fast charge carriers mobility and function-ability, carbon nanostructure is an attractive detector to dimethyl methylphosphonate (DMMP), imitation of nerve agents. Herein, 3D carbon nanostructure is constructed via in-situ growth of carbon nanofibers (CNFs) on electrospun CNFs (ECNFs), then activated with hexafluoroisopropanol (HFIP) to detect DMMP via H-bonding. To guarantee long-term stability, a designed holder that allows using pieces from sensing materials is used. Interestingly, 3D CNFs/ECNFs-HFIP exhibits a response of 25.5–1 ppm DMMP at room temperature (RT) under light irradiation, and maintains 88% of it in a humid environment, proving stability and humid independence. Compared with that in the dark and of ECNFs and ECNFs-HFIP, it is determined that the grafted HFIP and grown CNFs on ECNFs improve the DMMP detection. The fabric structure of 3D CNFs/ECNFs-HFIP provides a fast charge carriers pathway, quickening the response (2.4 s) and recovery (4.7 s) times. Overall the proposed strategies, the HFIP functionalized 3D carbon has a tremendous enticing to consider as an advanced CWAs sensing material.

Layered nanoreactor assisted to produce B-doped and P-doped 3D carbon nanostructures for supercapacitor electrodes

In the use of the electric double layer capacitors (EDLCs) with carbon electrode materials, what remains an important technological challenge is that existing carbon electrodes suffer from low energy density and low volumetric capacitance, the today's need for making energy storage architectures. The incorporation of the n-type and/or p-type dopant elements in carbon structure may result in an enhancement in the capacitance. Accordingly, the idea to use the layered nanoreactors was applied to produce phosphorous-doped and boron-doped porous carbon nanostructures with high specific capacitance (CS) values when used in supercapacitor electrodes. So that, the best P-doped and B-doped carbon electrodes show the CS values of 322 and 275 F/g, respectively, at a current density of 1 A/g in the three-electrode system. A symmetric supercapacitor device made using the best doped carbon material (CG-P) showed a CS value of 163.2 F/g at a current density of 0.1 A/g. Herein, this work shows that the high values of CS for carbon materials are due to high accessible surface area, excellent pore size distribution, the presence and uniform dispersion of the dopant agents in carbon structures.

Modification of graphenylene nanostructure with transition metals (Fe, Sc and Ti) to promote hydrogen storage ability: A DFT-D3 study

Hydrogen, as a clean alternative to fossil fuels, has received much attention in recent years. But its utilizing requires to overcome storage problems. Here, we investigated the hydrogen adsorption behavior of graphenylene (GPY), a 2D carbon nanostructure, and Sc, Fe and Ti transition metal (TM) decorated GPY by spin-polarized DFT calculations. For TM-decoration of GPY, seven different sites and various distances from carbon sheet were investigated, carefully. Structural and electronic properties of the structures, adsorption energies, band gap values, and the most stable configurations were considered and discussed. Results showed that 6-membered ring (H2 site) is the best site for Sc, Fe, and Ti-decoration and corresponding Eads was −3.95, −2.66, and −3.65 eV, respectively. Also, pristine GPY and Sc and Ti-decorated GPY have not magnetic character, unlike Fe-GPY. As well, entrance of Sc, Fe and Ti atoms in H2 site of the GPY structure causes its band gap increases from 0.033 eV to of 0.491, 0.080, and 0.372 eV, respectively. Eads of the H2 molecule onto pristine GPY is low (−0.160 eV), and must be improved for practical hydrogen storage applications. Sc, Fe, and Ti-decoration improves it about 2.23, 5.69 and 3.63 times. Because of this improvement, we could store up to 20H2 molecules on TM-decorated GPY systems. These results indicate that TM-decorated GPY can be a suitable option for H2 storage applications in the future.

Nickel oxide-1D/2D carbon nanostructure hybrid as efficient field emitters

Nickel oxide-1D/2D carbon nanostructure hybrid as efficient field emitters

Influence of 1D and 2D carbon nanostructures in silica-based aerogels

Carbon nanostructures-silica aerogel composites were synthesized and characterized to assess the effect of carbon nanotubes (CNTs) or graphene oxide (GO) on the silica aerogel properties. The sol-gel chemistry was based on methyltrimethoxysilane (MTMS) and 3-aminopropyltrimethoxysilane (APTMS) as silica precursor system, with varying amounts of APTMS (0–20% mol of Si). APTMS significantly impacted the materials' physical properties. The chemistry and microstructure were investigated by FTIR, NMR, TEM, SEM, SAXS and BET. The addition of CNTs induced the growth of the silica matrix around them; thus, an elongated shape was observed in the silica structural units. APTMS and CNTs have a synergistic effect on the mechanical properties, increasing the Young's modulus up to 14 MPa. Small amounts of carbon materials (∼1 wt%) in the MTMS-matrix improved its thermal insulation property, particularly for temperatures above 50 °C. In terms of electrochemical properties, the carbon nanostructures lead to higher specific capacitances and a reduction in resistance. The characterizations here performed allowed a better understanding of the interactions between the silica and carbon phases. The possibility to obtain materials with tailored properties demonstrates their application potential in several areas, such as thermal insulation and energy storage.

Trace Metal Loading of B‐N‐Co‐doped Graphitic Carbon for Active and Stable Bifunctional Oxygen Reduction and Oxygen Evolution Electrocatalysts

AbstractUnderstanding the structure‐property relations of non‐precious metal heteroatom co‐doped carbon electrocatalysts exhibiting high activity as well as long‐term durability for both ORR and OER remains challenging but is indispensable for the development of bifunctional ORR/OER electrocatalysts. We propose B‐N‐co‐doped graphitic 2D carbon nanostructures impregnated with controlled amount of transition metals (M‐BCN; M=Co, Ni, Fe, Cu) as bifunctional ORR/OER electrocatalysts. Co‐BCN outperformed the Ni‐, Fe‐, Cu‐based BCN catalysts exhibiting potential values of 0.87 V and 1.62 V at −1 mA/cm2 and 10 mA/cm2 during ORR and OER, respectively. Importantly, Co‐BCN shows bifunctional cyclic stability (Δη; EOER−EORR=0.75 V) of up to 300 cycles in 1 M KOH for a duration of 20 h with total activity loss of only 10.2 % (ORR) and 6.2 % (OER), respectively. A low loading of the metal precursors was used to preserve porosity and to facilitate the formation of metal nanoparticles or M−NxB/C type species embedded in the graphitic carbon layers. The B‐N‐co‐doped graphitic layers also protect the embedded metal nanoparticles explaining the observed long‐term stability.

Predicting an ideal 2D carbon nanostructure with negative Poisson's ratio from first principles: implications for nanomechanical devices

The intrinsic negative Poisson’s ratio effect at the level of molecule in two-dimensional nanomaterials, especially in the perfect planar nanostructures with a single atom thickness, is really rare and has attracted a lot of research interests because of its unique mechanical properties in the nanoscale and extensive applications in mechanical nanodevices. In this work, a novel ideal planar carbon nanostructure (PCNS) framework with a single atom thickness composed by carbon and hydrogen atoms is proposed and studied by means of first-principles density functional calculation. The results showed that the PCNS is, simultaneously, of excellent thermodynamic, molecular dynamic and mechanical stabilities. In addition, the electronic structure, mechanical characters, and optical-electronic characteristics of PCNS are also explored. Excitedly, it is found that the PCNS has a significant negative Poisson's ratio effect in plane, and the maximum value of Poisson's ratio is as high as − 2.094. Meanwhile, the material has a wide range of elastic mechanics. Moreover, the PCNS presents an ideal UV absorption performance. It is hoped that this work could be a useful structural design strategy for the development of the ideal 2D carbon-based nanomechanical devices with the intrinsic negative Poisson’s ratio effect and other electronic functions. An ideal 2D carbon nanostructure with negative Poisson's ratio was designed and its properties were investigated from first principles calculation.

Fracture fingerprint of polycrystalline C3N nanosheets: Theoretical basis

Polycrystalline carbon nanosheets are composed of several randomly rotated monocrystalline regions facing each other in grain boundaries-the cause of stress concentration-that affects the mechanics of 2D carbon nanostructures. They have been widely used in different fields, particularly in electronic devices. Herein, heterogeneous graphitic carbon nitride (C3N) was considered as typical of polycrystalline carbon nanosheets for modelling its fracture behavior. The number of grains with random configuration, temperature, and crack length were systematically changed to track the mode and the intensity of failure of model nanosheets. Molecular dynamics simulations predictions unraveled the interatomic interaction in the C–C and C–N bonds. An increase in the number of grain boundaries from 3 to 25 as well as the length of crack led to more than 70% fall in the Young’s modulus of polycrystalline carbon platelets. Stress intensity factor decreased against temperature, but increased by crack length enlargement demonstrating higher fracture toughness of small cracks. This theoretical approach can be generalized to capture the unique fracture fingerprint of polycrystalline carbon structures of different types.

An electrochemical immunosensor coupling a bamboo-like carbon nanostructure substrate with toluidine blue-functionalized Cu(ii)-MOFs as signal probes for a C-reactive protein assay.

In this paper, a novel sandwich immunosensor based on a toluidine blue (Tb) loaded metal organic framework (Cu(ii)-HKUST-1/Tb) as the signal element and a nitrogen-doped 3D carbon nanostructure as the electrode substrate was constructed for the detection of C-reactive protein (CRP). Tb as an electrochemically active agent usually forms a polymer by aggregation in the solvent, causing a poor electrochemical response. Therefore, in order to overcome this obstacle, Cu(ii)-HKUST-1 with a porous nanostructure and large specific surface area as a carrier could adsorb a large number of Tb molecules on its surface to improve its electrochemical performance. In addition, the high electron transfer efficiency of the N-doped bamboo-like carbon nanotubes (CoFe/N-GCT) improves the sensitivity of the biosensor. Differential pulse voltammetry (DPV) was used to detect the current signal of Tb at −0.2 V. The current response increased with the increase in concentration of CRP, ranging from 0.5 to 200 ng mL−1. The detection limit is 166.7 pg mL−1 (S/N = 3). Moreover, the proposed biosensor can be applied in real serum sample detection. It has potential applications in the field of biomedicine assays.