Nanocones Research Articles

Theoretical examination of oxygen reduction reaction (ORR) on carbon nanocone (CNC) for fuel cells

Recently, various studies were performed to propose and discover acceptable catalysts for oxygen reduction reaction (ORR) in various fuel cells. Here, performance of boron-doped carbon nanocone (CNC) as catalyst to ORR via theoretical methods is examined. The ORR paths through ER and LH mechanisms were studied. Results showed that onset-potential and over-potential on ORR of boron–CNC were 0.73 and 0.50 V, respectively. The calculated exchange current density and transfer coefficient of B–CNC were ca. 6.5 $$\times $$ 10 $$^{-6}$$ A cm $$^{-2}$$ and 0.52, respectively. Results demonstrate that boron-doped CNC is a high-potential catalyst to ORR.

Evaluating Adsorption of Proline Amino Acid on the Surface of Fullerene (C60) and Carbon Nanocone by Density Functional Theory

Determination of proline is of great importance and investigating the interaction of this amino acid with nanostructures play a key role in the construction of novel appropriate sensors for proline measurement. In this regard, proline adsorption on the surface of fullerene and carbon nanocone was studied by density functional theory. For this purpose, the structures of fullerene, nanocone, proline and proline-adsorbent complexes at two different configurations were optimized geometrically. Then, IR and Frontier molecular orbital calculations were done in the temperature range of 298.15-398.15 K at 10˚ intervals. The obtained adsorption energies, adsorption enthalpy changes, Gibbs free energy variations and thermodynamic equilibrium constants showed that the adsorption of proline on the surface of nanocone is exothermic, spontaneous, one sided and experimentally feasible. In this sense, proline adsorption on the fullerene is endothermic, non-spontaneous, balanced and experimentally impossible. The achieved specific heat capacity values reveal that carbon nanocone can be used in the development of thermal sensors for the determination of proline. The effect of temperature on the adsorption process was also checked out and the results indicate that 298.15 is the optimum temperature for the studied procedure. Some HOMO-LUMO parameters such as energy gap, electrophilicity, maximum charge capacity, chemical hardness and chemical potential were also evaluated. Accordingly, the findings demonstrate that carbon nanocone can be utilized in the electrochemical determination of proline.

Synthesis and (some) applications of carbon-nanotube-supported pyrolytic carbon nanocones

Graphene-based cones with nanosized apex can be obtained by means of a high temperature pyrolytic carbon depositionprocess using methane and hydrogen as gaseous feedstock and single carbon nanotubes as deposition substrates. Aside thecones, micrometer-sized carbon beads or fibre segments are deposited meanwhile which are a key morphological componentfor allowing handling and mounting the carbon cones and then using them for various applications. Based on both theliterature dealing with pyrolytic carbon deposition processes and experimental observations, a peculiar depositionmechanism is proposed, involving the transient formation of pitch-like liquid phase droplets which deposit onto theindividual carbon nanotubes. In this picture, it is believed that a key parameter is the diameter ratio for the droplets and thenanotubes, respectively. The cone concentric texture and perfect nanotexture are shown by high resolution transmissionelectron microscopy, which allows interesting mechanical and conducting properties to be predicted. Correspondingly,applications of the carbon nanocones as electron emitters for cold-field electron sources on the one hand, and as probes forvarious modes of near-field microscopy on the other hand, have been tested.

Adsorption of Tetranitrocarbazole on the Surface of Six Carbon-Based Nanostructures: A Density Functional Theory Investigation

In this study, the interaction of Tetranitrocarbazole (TNC) with six various carbon-based nanostructures including carbon nanotubes, graphene, carbon nanocones and three fullerenes (C20, C24 and C60) was investigated by Density functional theory (DFT). The calculated adsorption energies, Gibbs free energy changes, enthalpy variations and thermodynamic equilibrium constants revealed that the adsorption of TNC is exothermic process, spontaneous, one-sided, non-equilibrium and experimentally feasible on the surface of all of the studied nano-adsorbents except carbon nanotube. The increasing of N–O and C–NO2 bond lengths after reacting with nano-substituents proved that the energetic and explosive properties of TNC has defused significantly. The computed density values substantiated the detonation pressure and explosive velocity of TNC have improved after adsorbing on the surface of C20.Some frontier molecular orbital parameters such as band gap, chemical hardness, electrophilicity, chemical potential and charge capacity were also studied and the results showed that C20 is an ideal candidate for being used as a sensing material in the construction of TNC conductometric sensor. Graphenecould also be utilized as an electroactive sensing material in the development of TNC selective potentiometric electrodes.

Mechanistic modeling of spontaneous penetration of carbon nanocones into membrane vesicles.

Carbon nanocones (CNCs) are promising drug delivery systems that can be functionalized with a variety of biomolecules (such as proteins, peptides, or antibodies), which allow for site-specific, targeted payload delivery to particular cells and organs. However, considerable uncertainty exists with respect to the toxicity of CNCs on their conical shape, and the underlying mechanism that leads to the penetration of CNCs (especially the truncated ones) in and through the cell membrane is not yet well understood. Using a coarse-grained dissipative particle dynamics method, we systematically investigate the spontaneous penetration of untruncated and truncated CNCs into membrane vesicles. For untruncated CNCs, the simulation results show that both pristine and oxidized ones can spontaneously penetrate across or be attached to the vesicle surface without membrane rupture, indicating low or insignificant toxicity. However, for truncated CNCs, we find that both the apex angle and aspect ratio can influence the CNC-membrane interactions and CNC-induced toxicity: a higher apex angle (and/or a lower aspect ratio) yields a higher toxicity of truncated CNCs. Further free energy analysis reveals that the lowest free energy path during the penetration is associated with CNC's orientation and rotation. For a truncated CNC with a low aspect ratio and high apex angle, it tends to rotate itself to a preferred standing-up fashion inside the vesicle membrane, posing an enhanced toxicity of CNCs. These findings may provide useful guidelines for designing effective CNC vehicles for drug delivery.

DFT Study of Catalytic CO2Hydrogenation over Pt-Decorated Carbon Nanocones: H2Dissociation Combined with the Spillover Mechanism

In this work, we investigate the catalytic role of platinum-decorated defective CNC (Pt/dCNC) in CO2 hydrogenation to formic acid (FA) by a density functional theory (DFT) approach. The reaction follows the equation CO2(g) + H2(g) → HCOOH(g). Combining highly reactive Pt atoms with defective CNC provides Pt/dCNC, a reactive monodispersed atomic catalyst for CO2 hydrogenation. We propose our new mechanism of CO2 hydrogenation over the Pt/dCNC catalyst involving a H2 dissociation and H spillover sequence that is energetically favorable. The rate-determining step is formic acid desorption that requires an energy barrier of 1.11 eV. Furthermore, our findings show that the rate of FA production is dependent on H2 concentration. Altogether, the theoretical results support the concept of the spillover mechanism, playing a key role in promoting CO2 hydrogenation via a formate intermediate. These results improve our understanding of the mechanism involving H2 dissociation with the H spillover process and the catal...

On topological indices of carbon nanocones and nanotori

AbstractLet G be a graph with n vertices and d i is the degree of its ith vertex (d i is the degree of v i). In this article, we compute the redefined first Zagreb index, redefined second Zagreb index, redefined third Zagreb index, augmented Zagreb index of graphs carbon nanocones CNC k[n], and nanotori [C4C6C8(p,q)]. Also, compute the multiplicative redefined first Zagreb index, multiplicative redefined second Zagreb index, multiplicative redefined third Zagreb index, multiplicative augmented Zagreb index of carbon nanocones CNC k[n], and nanotori [C4C6C8(p,q)].

Computational aspects of line graph of carbon nanocones

Graph theory plays substantial role in mathematics, chemistry, QSAR and physical sciences. The basic layout of the graph theoretic model is a molecular structure in which vertices of the graph correspond to atoms, and edges correspond to chemical bonds. The study of this graph model provides information about the chemical structure. A line graph has many useful applications in physical chemistry. M-polynomial is rich in producing closed forms of many degree-based topological indices which correlates chemical properties of the material under investigation. This polynomial is used in computing closed formulas of many degree-based topological invariants of the molecular structures. The molecular graph of carbon nanocones has a conical structure with a cycle of length k at its core and n layers of hexagons placed at the conical surface around its centre. In this study, we transformed the molecular structure of carbon nanocones into graph theoretic model and produced its line graph. Thereafter, we determined closed formulas for M-polynomials of line graphs of nanocones. We also recovered important topological degree-based indices of the line graph of nanocones. Moreover, we provide different graphs of topological indices and their relations with the parameters of the line graph of nanocones. These graphs depict the actual dependencies of the topological indices on the parameters of the carbon nanocones.

Comparing quantum, molecular and continuum models for graphene at large deformations

In this paper, the validity and accuracy of three interatomic potentials and the continuum shell model of Ghaffari and Sauer [1] are investigated. The mechanical behavior of single-layered graphene sheets (SLGSs) under uniaxial stretching, biaxial stretching and pure bending is studied for this comparison. The validity of the molecular and continuum models is assessed by direct comparison with density functional theory (DFT) data available in the literature. The molecular simulations are carried out employing the MM3, Tersoff and REBO + LJ potentials. The continuum formulation uses an anisotropic hyperelastic material model in the framework of the geometrically exact Kirchhoff-Love shell theory and isogeometric finite elements. Results from the continuum model are in good agreement with those from DFT. The results from the MM3 potential agree well up to the point of material instability, whereas those from the REBO + LJ and Tersoff potentials agree only for small deformations. Only the Tersoff potential is found to yield auxetic response in SLGSs under uniaxial stretch. Additionally, the transverse vibration frequencies of a pre-stretched graphene sheet and a carbon nanocone are obtained using the continuum model and molecular simulations with the MM3 potential. The variations of the frequencies from these approaches agree within an error of ≈5%.

Review on the interface engineering in the carbonaceous titania for the improved photocatalytic hydrogen production

Hydrogen is the prime source of energy with enormous attention in the current research development process as it is safe, clean, eco-friendly, and can be produced from renewable resources through simple catalytic reactions. Scalable production of hydrogen through photocatalysis has been achieved using carbon-modified semiconductors since 2009. In this direction, this review delivers comprehensive understandings into the interface and structural interactions between TiO2 and carbonaceous materials such as carbon, carbon nanotubes, graphene, activated carbon, graphitic carbon nitride, carbon quantum dots, etc., and their influences toward improving the hydrogen generation activity of these systems. Besides, recently developed carbonaceous materials such as 3-D graphene, carbon nanohorns, and carbon nanocones have also been discussed on their character in the photocatalytic water splitting procedure. In general, the observed improvements in this carbon-modified TiO2 attributed to the synergetic effects, which offer the active migration of charge carriers and reduced recombination rates in the photocatalyst. Finally, highlighting the future perspectives of the carbonaceous materials in photocatalytic applications are concluded.

Simultaneous Improvement of Absorption and Separation Efficiencies of Mo:BiVO4 Photoanodes via Nanopatterned SnO2/Au Hybrid Layers

BiVO4 has a thickness limitation because of carrier diffusion length; thus, the light-absorption efficiency is limited. To resolve this issue, we propose coating Mo:BiVO4 on nanopatterned electrodes fabricated via direct-printing technology, which is the most suitable patterning technology for energy-related fields in cases where cost effectiveness is important. We designed two types of nanoelectrodes: nanocone (NC) and reverse NC (RNC). Nanopatterned electrodes mitigate the problems of the short carrier-diffusion length, allowing a larger amount of Mo:BiVO4 to be coated. Also, the Au electrode acts as a back reflector, causing multiple light scattering. The nanopatterned electrode increases the carrier-separation efficiency and the light-absorption efficiency simultaneously owing to the larger amount of Mo:BiVO4 and multiple light scattering. The photocurrent densities of the Au/SnO2/Mo:BiVO4 NC electrode, a corresponding RNC electrode, and a flat electrode were 1.53, 1.35, and 0.44 mA/cm2, respectively, at 1.23 VRHE under 1-sun illumination.

Edge Distance-based Topological Indices of Strength-weighted Graphs and their Application to Coronoid Systems, Carbon Nanocones and SiO2 Nanostructures.

The edge-Wiener index is conceived in analogous to the traditional Wiener index and it is defined as the sum of distances between all pairs of edges of a graph G. In the recent years, it has received considerable attention for determining the variations of its computation. Motivated by the method of computation of the traditional Wiener index based on canonical metric representation, we present the techniques to compute the edge-Wiener and vertex-edge-Wiener indices of G by dissecting the original graph G into smaller strength-weighted quotient graphs with respect to Djoković-Winkler relation. These techniques have been applied to compute the exact analytic expressions for the edge-Wiener and vertex-edge-Wiener indices of coronoid systems, carbon nanocones and SiO2 nanostructures. In addition, we have reduced these techniques to the subdivision of partial cubes and applied to the circumcoronene series of benzenoid systems.

Mostar indices of carbon nanostructures and circumscribed donut benzenoid systems

AbstractOn the great success of bond‐additive topological indices such as Szeged, Padmakar‐Ivan, Zagreb, and irregularity measures, yet another index, the Mostar index, has been introduced recently as a quantitative refinement of the distance nonbalancedness and also a peripherality measure in molecular graphs and networks. In this direction, we introduce other variants of bond‐additive indices, such as edge‐Mostar and total‐Mostar indices. The present article explores a computational technique for Mostar, edge‐Mostar, and total‐Mostar indices with respect to the strength‐weighted parameters. As an application, these techniques are applied to compute the three indices for the family of coronoid and carbon nanocone structures.

Fabrication of nanocones by RIE on GaP

GaP(111)B substrate was etched through colloidal self-assembled randomly distributed 30nn Au nanoparticles by RIE. We looked into how GaP nanocones (NCs) formed with respect to the chamber pressure and etching duration, and the use of electron cyclotron resonance (ECR) RIE mode. The NCs were steep-walled in RIE, and those produced by ECR RIE were bell shaped. The NC length increased with etching duration for the same chamber pressure. The NCs were shorter and slightly steeper with decreased pressure for the same etching duration. The NCs that had the Au particles eradicated during the etching process became blunt and were gradually diminished.

Synthesis of a Carbon Nanocone by Cascade Annulation.

More than 50 years have passed since the first observation of graphitic cones in the pyrolysis of carbon. However, to date there has been no report in the literature on the synthesis of such carbon allotropes. Here we present the first synthesis of a carbon nanocone, which comprises a pentagon encircled by 30 hexagons, by means of a palladium-catalyzed cross-coupling reaction. In this synthetic approach, 15 C-C bonds were constructed from a cone-shaped aromatic scaffold, corannulene, and five naphthalene dicarboximide moieties through a cascade of [3 + 3] and [4 + 2] annulations. The conical geometry of the first synthetic carbon nanocone was confirmed by X-ray crystallography. The optical and electronic properties of this graphitic cone were elucidated by UV/vis and fluorescence spectroscopy and cyclic voltammetry.

A novel super-elastic carbon nanofiber with cup-stacked carbon nanocones and a screw dislocation

Carbon nanofibers (NFs) have been envisioned with broad promising applications, such as nanoscale actuators and energy storage medium. This work reports for the first-time super-elastic tensile characteristics of NFs constructed from a screw dislocation of carbon nanocones (NF–S). The NF–S exhibits three distinct elastic deformation stages under tensile, including an initial homogeneous deformation, delamination, and further stretch of covalent bonds. The delamination process endows the NF–S extraordinary tensile deformation capability, which is not accessible from its counterpart with a normal cup-stacked geometry. The failure of NF–S is governed by the inner edges of the nanocone due to the strain concentration, leading to a common failure force for NF–S with varying geometrical parameters. Strikingly, the delamination process is dominated by the inner radius and the apex angle of the nanocone. For a fixed apex angle, the yielding strain increases remarkably when the inner radius increases, which can exceed 1000%. It is also found that the screw dislocation allows the nanocones flattening and sliding during compression. This study provides a comprehensive understanding on the mechanical properties of NFs as constructed from carbon nanocones, which opens new avenues for novel applications, such as nanoscale actuators.

Reinforcement of alumina with carbon nano cones and characterization

Pure alumina powder is synthesized by solid state reaction method, wherein aluminium nitrate nano hydrate is annealed for 3 h at 1000 °C in muffle furnace. Carbon nano cones, as a reinforcer, are added to pure alumina in different weight proportions such as 0.5%, 2.5% and 4% and annealed at 1000 °C for 3 h in nitrogen atmosphere. The synthesized samples were characterized using XRD, SEM and DRS techniques to estimate crystallite size, interplanar distance and band gap. SEM reveals the surface morphologies of all samples and a rough estimate of crystallite sizes varying from few nm to 15 µm.

Development of methods to investigate the mechanisms behind increased behavioral reactivity associated with an increased-starch diet

In recent years, the discovery of catalysts with high performance to oxidation of nitrogen monoxide (NO) is important. In present study, in first step the carbon nanocone (CNC) with Sn was doped and the surface of Sn-doped CNC via O2 molecule was activated. In second step, the NO oxidation on surface of Sn-CNC via Langmuir Hinshelwood (LH) and Eley Rideal (ER) mechanisms was investigated. Results show that O2-Sn-CNC can oxidize the NO molecule via Sn-CNC-O-O⁎ + NO → Sn-CNC-O-O⁎-NO → Sn-CNC-O⁎ + NO2 and Sn-CNC-O⁎ + NO → Sn-CNC + NO2 reactions. Results show that energy barrier of oxidation of NO molecule on surface of Sn-CNC via the ER mechanism (0.23 eV) is lower than LH mechanism (0.67 eV) ca 0.44 eV. Finally, calculated parameters reveal that activated Sn-CNC is acceptable catalyst with high performance to oxidation of NO molecule.

Two-dimensional oligoglycine tectomer adhesives for graphene oxide fiber functionalization

Amino-terminated oligoglycine two-dimensional (2D) peptide self-assemblies (known as tectomers) have a versatile surface chemistry that allows them to interact with a variety of nanomaterials and to act as supramolecular adhesives for surface functionalization. Here, we have exploited the strong hydrogen-bond based interaction between tectomers and graphene oxide (GO) to functionalize GO fiber surfaces with different carbon nanomaterials (carbon nanotubes, carbon nanohorns, carbon nanocones, and highly fluorescent nanodiamonds), metal (gold, platinum, iron) nanoparticles, acrylate-based polymer nanoparticles, fluorophores and drugs. The resulting ultrathin coatings exhibit remarkable water resistant properties. This tectomer-mediated fiber decoration strategy allows coating functionalities to be tailored by choosing the appropriate nanomaterials or other molecules. We show that this strategy can be extended to other fibers and fabrics, such as polyurethane/PEDOT:PSS, poly(methyl methacrylate) and polyester, making it very attractive for a variety of technological and smart textile applications.

Development of Acoustically Active Nanocones Using the Host-Guest Interaction as a New Histotripsy Agent.

Histotripsy is a noninvasive and nonthermal ultrasound ablation technique, which mechanically ablates the tissues using very short, focused, high-pressured ultrasound pulses to generate dense cavitating bubble cloud. Histotripsy requires large negative pressures (≥28 MPa) to generate cavitation in the target tissue, guided by real-time ultrasound imaging guidance. The high cavitation threshold and reliance on real-time image guidance are potential limitations of histotripsy, particularly for the treatment of multifocal or metastatic cancers. To address these potential limitations, we have recently developed nanoparticle-mediated histotripsy (NMH) where perfluorocarbon (PFC)-filled nanodroplets (NDs) with the size of ∼200 nm were used as cavitation nuclei for histotripsy, as they are able to significantly lower the cavitation threshold. However, although NDs were shown to be an effective histotripsy agent, they pose several issues. Their generation requires multistep synthesis, they lack long-term stability, and determination of PFC concentration in the treatment dose is not possible. In this study, PFC-filled nanocones (NCs) were developed as a new generation of histotripsy agents to address the mentioned limitations of NDs. The developed NCs represent an inclusion complex of methylated β-cyclodextrin as a water-soluble analog of β-cyclodextrin and perfluorohexane (PFH) as more effective PFC derivatives for histotripsy. Results showed that NCs are easy to produce, biocompatible, have a size <50 nm, and have a quantitative complexation that allows us to directly calculate the PFH amount in the used NC dose. Results further demonstrated that NCs embedded into tissue-mimicking phantoms generated histotripsy cavitation “bubble clouds” at a significantly lower transducer amplitude compared to control phantoms, demonstrating the ability of NCs to function as effective histotripsy agents for NMH.