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Background: Alzheimer’s disease is an irreversible, progressive brain disorder manifested with symptoms like loss of memory (known as dementia), personality changes, loss of cognition, impaired movement, confusion, deteriorated planning and thought process. Neurodegeneration in Alzheimer’s disease is the result of deposition of protein beta-amyloid that forms plaques and another protein called tau, forming tangles that prevent proper functioning of nerve cells in the brain. Methods: The goal of the review was to comprehensively study the utilization of nanotechnology and the role that carbon nanotubes can play as a drug delivery system for amelioration of Alzheimer’s disease. Results: Nanotechnology is one of the most researched domains of modern science. It contributes significantly to therapeutics by facilitating drug therapy to reach the target sites, which are otherwise difficult to reach with conventional drug delivery systems. Carbon nanotubes are the allotropes of carbon in which several carbon atoms bind with each other to form a cylindrical or a tube-like structure. The carbon nanotubes possess several unique qualities, which confer them with a high potential of being utilized as an efficient drug delivery system. They offer high drug loading and can readily cross the toughest biological barriers like the BBB. Carbon nanotubes also facilitate the passage of drugs to the brain via the olfactory route, which further helps in restoring normal autophagy, thus preventing the elimination of autophagic chemicals. They can carry a vast range of cargos, including drugs, antigens, genetic materials, and biological macromolecules. Conclusion: Carbon nanotubes are a highly promising drug delivery system for anti-Alzheimer’s drugs. They have the potential of overcoming the various biological barriers like the BBB. However, more extensive research is required so as to set up a firm base for the development of advanced commercial products based on carbon nanotubes for the treatment of Alzheimer’s disease.

The exploration of the synthesis methods of sp2 and sp3 carbon nanomaterials under ambient conditions is very meaningful towards their industrial applications. The existing bottom-up synthesis methods usually need high temperature or high pressure conditions. We report a facile and environmentally-friendly approach enabling the synthesis of almost all types of known carbon nanostructures at room temperature and under atmosphere pressure. They include both sp3-structured n-diamond (not cubic diamond) nanocrystals and sp2-structured graphene, defective multiwalled carbon nanotubes, defective carbon nano-onions as well as graphene polyhedra. The reaction of ethanol and potassium hydroxide at ambient conditions yields n-diamond nanocrystals. To synthesize the sp2 carbon nanomaterials, the assistance of the ultrasonic shock at the early stage of crystallization is necessary to ensure the formation of the carbon ring nucleation seeds. The synthetic yields of n-diamond nanocrystals, graphene polyhedra, defective carbon nano-onions, and graphene are estimated to be 0.37%, 0.30%, 0.04%, and 0.01% (carbon mass ratio), respectively, and all of them have good crystallinity. These results improve our understanding of the low-temperature crystal growth process of the carbon nanostructures.

As the known allotropes of carbon have expanded, increasing interest has been shown in one-dimensional carbyne. One approach to studying carbyne has been to synthesize linear carbon chains (LCCs) w...

The scarcity of nonrenewable resource motivated inclination towards the environmental-friendly novel materials and development of waste natural filler-based hybrid composite is encouraged to fulfill the material demand. Epoxy resins-based composites are high-performing thermosetting polymers and have outstanding blending properties, good machinability, and low cost. Due to these advantages, thermoset plastic is largely used in a broad range of engineering applications; however, thermomechanical properties of neat epoxy are low. Thus, to enhance the thermomechanical properties of epoxy, it is interfaced materials such as graphite, graphene nanoplatelet, boron, carbon fiber, aluminium, silver, etc. Among various substances, graphene has been deliberated as an acceptable novel filler because of its exceptional properties. In addition to inorganic filler inclusion, natural filler/fiber like hemp, sisal, flax, bamboo, jute, etc. can be utilized in a higher percentage as biodegradable material. The present article assisted to improve thermomechanical properties of neat epoxy. This work identifies and addresses (i) processes used for graphene modification; (ii) treatment utilized for enhancing the binding properties of natural filler; (iii) various natural filler extraction process employed; (iv) neat epoxy modification; and (v) influence of different dimensions of fillers.

Carbon nanotubes (CNTs), the one-dimensional allotropes of carbon, have attracted noteworthy research interest since their discovery in 1991 owing to their large aspect ratio, low mass density, and unique chemical, physical, and electronic properties that provide exciting possibilities for nanoscale applications. Nonetheless, two major issues should be considered when working with this sort of nanomaterial: their strong agglomerating tendency, since they are typically present as bundles or ropes of nanotubes, and the metallic impurities and carbonaceous fragments that go along with the CNTs. The successful utilization of CNTs in a wide variety of applications—in particular, in the field of polymer composites—depends on their uniform dispersion and the development of a strong chemical interaction with the polymeric matrix. To achieve these aims, chemical functionalization of their sidewalls and tips is required. In this article, a brief overview of the different approaches for CNT modification using polymers is provided, focusing on the covalent functionalization via “grafting to” or “grafting from” strategies. The characteristics and advantages of each approach are thoroughly discussed, including a few typical and recent examples. Moreover, applications of polymer-grafted CNTs as biosensors, membranes, energy storage substances, and EMI shielding are briefly described. Finally, future viewpoints in this vibrant research area are proposed.

Graphene is a proficient anode material for super capacitors. A few reasons can be credited to the current enthusiasm for graphene as a special morphology carbon material with potential for electrochemical vitality stockpiling applications. Graphene has predominant electrical conductivity than graphite and different allotropes of carbon due to its high surface region and substance resilience. In this work, Graphene Oxide was blended by adjusted Hummer's strategy and it was decreased to graphene utilizing hydrazine hydrate. Graphene-Calcium titanate composites were set up by arrangement blending technique. Moreover, its morphology and properties were portrayed by X-beam diffraction (XRD), filtering electron magnifying instrument (SEM), Fourier change infrared spectroscopy (FT-IR), and electro-synthetic estimations. The as-arranged nano composites were tried for its super capacitance property by cyclic voltammetric (CV) explore in 2 M KOH electrolyte. CV was performed at an expected scope of 0.6 to – 0.6 V at 100 mV/s examine rate, and results show a great capacitive conduct of the nano composites.

An anti-bacterial material coating can help to break the spread of bacteria and viruses via metallic surfaces of biomedical devices, communication devices, food packages, research laboratories and public infrastructures like shopping malls, transports, toilets, etc. In addition, anti-bacterial material coatings owing to adequate tribomechanical and anti-corrosion properties can also help to resolve a major engineering problem of biofouling on marine installations and watercrafts’ surfaces. In recent times, the use of anti-bacterial nanocomposites coatings is emerging rapidly for various engineering applications. Here, metal matrix nanocomposites (MMNCs) are acquiring a significant role in the upcoming field of anti-bacterial material applications owing to high tribo-mechanical and anti-corrosion properties. The bio-responsive mechanism of MMNC coatings to perform anti-bacterial activities can protect the surfaces in biological environments. The nanofillers in the metal matrix plays a key role during anti-bacterial activities to kill the microbials. The composition of nanofillers can be inorganic, organic and hybrid, including advance nano tropes (i.e., allotropes of carbon and BNNT), which can be reinforced in metal matrix. This review study is addressing a problem of bacterial colonization on the surfaces that causing microbial growth based novel engineering problems and suggesting a facile and low-cost solution through an anti-bacterial MMNC coating.

Carbon nano-onions (CNOs), as one of the allotropes of carbon, have attracted great attention because of their excellent performance in many fields, especially in capacitors. Developing soft-chemistry synthesis methods is critically of importance, while the forming mechanism in this area is not clear. In this paper, we present a critical review of CNOs regarding the structure, especially interlayer spacing, and synthesis processes, elaborating the recent progress on soft-chemistry methods. Hansen solubility parameter theory is applied to predict and regulate the solubility of CNOs. This article would be inspirational and give new insights into understanding the formation and properties of CNOs.

Graphene is just single layer of carbon atom compactly bound in hexagonal honeycomb lattice. Graphene is the component of different allotropes of carbon like CNT, graphite, diamond, charcoal and fullerene. In graphene the bonding orbital is Sp2 hybridized using only three out of the four valence electrons of carbon. The well-known 3-D graphitic crystal is formed by stacking graphene layers on top of one another. Its prominent physical, electronic as well as mechanical properties originate from the two-dimensional (2D) electronic confinement within the one-atom-thick layer. Graphene was fabricated by electrochemical exfoliation method in an aqueous medium. The electrolytic bath contains 0.1 M ferrous sulfate (FeSO4). Two high purity graphite rods, placed parallel to each other with a separation of 2.0 cm, were inserted as electrodes into solution of water and a consistent potential about 15–20 V was applied between the two graphite rods. Different characterization methods were used to evaluate the presence of graphene. The exfoliated graphene (EG) showed a diffraction peak at 2θ = 26.4°with (0 0 2) plane with intensity much less than that of graphite. The absorption peak of graphene appeared at 267 nm which is recognized to π-π* transition of C-O bonds due to the exfoliation and the intercalation on graphene. The photoluminescence (PL) peak was observed at 418 nm. The surface morphology shows the wrinkled paper-like appearance which is the characteristic of graphene.

The allotropes of carbon have been the focus of attention in recent years. In this work, we reported a molecular allotrope of carbon, C60-endohedral: (C=C=C=C)@C60. The smallest vibrational frequency is 226.0 cm-1, which confirms that (C=C=C=C)@C60 is a minimum on the potential energy hypersurface. Its geometry, NMR diagram, IR spectrum, heat of formation, and bonding interactions have been predicted using the density functional theory (DFT) method at the B3LYP/6-311G(d) level of theory. Since there must be a large family of the fullerene-endohedral allotropes of carbon, the research studies on these allotropes of carbon will open an avenue for allotropes of carbon.

This research aims to scrutinize the impact of graphene additive on the consolidation behavior, microstructure and physical-mechanical qualifications of TiC-based materials. For this purpose, two specimens, namely monolithic TiC and TiC-5 wt% graphene, were produced using the spark plasma sintering (SPS) method at 1900 °C. An external pressure of 40 MPa was applied during the sintering, and the ceramics were held at the maximum temperature for 10 min. The characteristics of SPSed samples were studied using scanning electron microscopy (SEM) and X-ray diffraction (XRD). Although adding graphene had no notable effect on the sinterability of TiC, it led to an increment in the flexural strength of graphene-doped sample. The microstructural assessment revealed the positive influence of graphene additive on obtaining a finer microstructure. The phase analysis confirmed the appearance of a non-stoichiometric hexagonal TiCx and different allotropes of carbon in the samples. Finally, the highest values for Vickers hardness (~3130 HV0.1Kg) and flexural strength (~530 MPa) were attained for the monolithic TiC and graphene-reinforced samples, respectively.

In this study, the hydrogen storage performance of commercial AZ31-Mg alloys combined with various allotropes of carbon was investigated and the microstructural modifications with respect to plastic deformation and high energy milling techniques investigated, with the aim of obtaining enhanced hydrogen storage efficiency. The hydrogen storage performance of alloys prepared with different weight ratios of carbonaceous materials as a catalyst was monitored in order to explore the effective improvement in hydrogen storage performance through microstructural modification. Additionally, the effects of different processing methods such as equal channel angular pressing (ECAP) and high energy ball milling (HEBM) were also observed. AZ31 Mg based composites with various carbon additives were produced through gravity resistance casting and their micrographic structures examined through optical Microscopy (OM), X-ray diffraction (XRD) and scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS). The average particle size distributions of the sample powders were also measured. The rate of hydrogenation kinetics was calculated by a Sievert's type apparatus. Significant enhancement of the hydrogenation performance was obtained with the addition of carbonaceous materials. Overall, the hydrogen storage performance after ECAP deformation of the AZ31-3CB (carbon Black) composite showed a gain in the maximum capacity of 6.72 ± 0.05 wt%. Similar, after milling of the AZ31-3G (Graphene) composite materials, a maximum potential capacity of 6.83 ± 0.04 wt% was attained within 792 ± 144.34 s, with desorption of the entire H2 content in 143.2 ± 26.09 s. The obtained results revealed significant improvement in the hydrogen storage capacity of AZ31-Mg alloys with the addition of carbon materials and with respect to plastic deformation and milling techniques.

Linear carbon chains (LCCs) are a one-dimensional sp1-hybridized allotrope of carbon. LCCs are extremely unstable: The longer the LCCs, the less stable the materials. Thus, it is a big challenge to synthesize long LCCs. Although the research on the short LCCs, e.g., polyynes, can be traced back to the 18th, LCCs are still not well-known compared to other allotropes of carbon, e.g., fullerenes, carbon nanotubes and graphene. Therefore, introducing recent progress on LCCs is of great significance to draw more attention in the community of nanocarbons as well as nanomaterials in general. Theoretically, various excellent properties have been predicted. Experimentally, LCCs with different length in many kinds of forms have been successfully synthesized. In this review, we summarized recent studies of polyynic LCCs from both theoretical and experimental aspects. Also, perspectives are highlighted to point out the further investigations of the materials.

Samples of thermally reduced graphene oxide are studied using differential cross sections for photoelectron inelastic energy losses. We compare different procedures for recovering cross sections from the photoelectron energy spectra resulting from multiple inelastic scattering. It is shown that the cross section for inelastic energy losses (which uniquely characterizes allotropes of carbon) in the sample containing the minimal amount of carbon oxides corresponds the best to pyrolytic graphite.

Current discoveries as well as research findings on various types of carbon nanostructures have inspired research into their utilization in a number of fields. These carbon nanostructures offer uses in pharmacy, medicine and different therapies. One such unique carbon nanostructure includes carbon nanotubes (CNTs), which are one-dimensional allotropes of carbon nanostructure that can have a length-to-diameter ratio greater than 1,000,000. After their discovery, CNTs have drawn extensive research attention due to their excellent material properties. Their physical, chemical and electronic properties are excellent and their composites provide great possibilities for enormous nanometer applications. The current study provides a systematic review based on prior literature review and data gathered from various sources. The various research studies from many research labs and organizations were systematically retrieved, collected, compiled and written. The entire collection and compilation of this review concluded the use of CNT approaches and their efficacy and safety for the treatment of various diseases such as brain tumors or cancer via nanotechnology-based drug delivery, phototherapy, gene therapy, antiviral therapy, antifungal therapy, antibacterial therapy and other biomedical applications. The current review covers diverse applications of CNTs in designing a range of targeted drug delivery systems and application for various therapies. It concludes with a discussion on how CNTs based medicines can expand in the future.

As the main load-bearing structure in the human body, bone and cartilage are susceptible to damage in sports and other activities. The repair and regeneration of bone and articular cartilage have been extensively studied in the past decades. Traditional approaches have been widely applied in clinical practice, but the effect varies from person to person and may cause side effects. With the rapid development of tissue engineering and regenerative medicine, various biomaterials show great potential in the regeneration of bone and cartilage. Carbon-based nanomaterials are solid materials with different structures and properties composed of allotropes of carbon, which are classified into zero-, one-, and two-dimensional ones. This Review systemically summarizes the different types of carbon-based nanomaterials, including zero-dimensional (fullerene, carbon dots, nanodiamonds), one-dimensional (carbon nanotubes), and two-dimensional (graphenic materials) as well as their applications in bone, cartilage, and osteochondral regeneration. Current limitations and future perspectives of carbon-based nanomaterials are also discussed.

Doping and its consequences on the electronic features, optoelectronic features, and magnetism of graphynes (GYs) are reviewed in this work. First, synthetic strategies that consider numerous chemically and dimensionally different structures are discussed. Simultaneous or subsequent doping with heteroatoms, controlling dimensions, applying strain, and applying external electric fields can serve as effective ways to modulate the band structure of these new sp2/sp allotropes of carbon. The fundamental band gap is crucially dependent on morphology, with low dimensional GYs displaying a broader band gap than their bulk counterparts. Accurately chosen precursors and synthesis conditions ensure complete control of the morphological, electronic, and physicochemical properties of resulting GY sheets as well as the distribution of dopants deposited on GY surfaces. The uniform and quantitative inclusion of non-metallic (B, Cl, N, O, or P) and metallic (Fe, Co, or Ni) elements into graphyne derivatives were theoretically and experimentally studied, which improved their electronic and magnetic properties as row systems or in heterojunction. The effect of heteroatoms associated with metallic impurities on the magnetic properties of GYs was investigated. Finally, the flexibility of doped GYs’ electronic and magnetic features recommends them for new electronic and optoelectronic applications.

Deactivation of catalysts due to rapid blocking of active surfaces and pores is a major problem for methane cracking. The removal of the template using different calcination methods contributes to the different characteristics of catalyst support. Therefore, silica supports were prepared with the sol–gel method, where sodium silicate and chitosan are a silica source and a template, respectively. Calcination using a microwave muffle furnace (MWF) was preferred over the conventional electric muffle furnace at the heating rates of 2 and 17 °C/min (CEF2 and CEF17, respectively) in order to remove the chitosan template. A nickel nitrate precursor was loaded onto the obtained silica supports by the incipient wetness impregnation method. The properties of the silica support and the Ni/SiO2 catalysts were characterized by means of N2-sorption, X-ray diffraction, scanning electron microscopy–energy-dispersive X-ray, field emission transmission electron microscopy, and H2 temperature-programmed reduction. The catalytic activity was evaluated using a fixed-bed reactor at 550 °C with a CH4/N2 ratio of 1:4 in the feed. The amount and the allotropes of carbon deposited on the spent catalysts were investigated using thermogravimetric/differential thermal analysis. The results showed that the SiO2-MWF support had a higher surface area and a larger pore volume of a mesoporous structure with larger interparticle channels than that of the SiO2-CEF supports. This leads to the higher dispersion of Ni metal particles over and inside the interparticle channels of the SiO2-MWF support. This provided a higher metal–support interaction, resulting in lower rates of methane conversion and carbon deposition on the catalyst surface than those of Ni/SiO2-CEF catalysts. However, it displayed a lower bed pressure. It was found that the carbon fibers deposited on all the catalysts were multiwalled carbon nanotubes (MWCNTs). Additionally, the base-growth mechanism of MWCNTs was only exhibited by the Ni/SiO2-MWF catalyst.

2-dimensional allotropes of carbon have lately attracted significant research interests owing to their unique electronic and structural properties. Such sp and sp2 bonded atomic systems, i.e. graphdiyne and graphene are well represented in the forefront of theoretical and experimental chemistry. However, no stable sp3 bonded 2-dimensional all-carbon atomic structure has been identified yet. To this end, using state-of-the-art theoretical calculations, we considered cyclobutane motifs, and investigated whether a sp3 bonded 2-dimensional carbon allotrope could be achieved by assembling ladderane chains. Energetic and dynamic stability studies yielded two such promising structures: one with 4-coordinated carbon atoms and a relatively more stable structure with a combination of 3 and 4-coordinated carbon atoms; both having puckered geometries and partially sp3 C-C bonds. However thermal stability investigations indicated only the lower energy configuration could be stable at ambient temperature and pressure. The higher energy structure was found to be metastable and was observed to suffer phase-transitions towards the lower energy structure or other stable 2-dimensional allotropes of carbon under exposure to ambient conditions. Investigation of electronic properties of these proposed materials revealed them to be direct-gap semiconductors with small bandgaps, and their tunability by applying external strain implied wide scope of applications.

Objectives: Carbon nanotubes (CNTs) are allotropes of carbon with a length-to-diameter ratio greater than 106 with the potential uses as medical diagnostic or therapeutic agents. In vitro studies have revealed that gadolinium (Gd) nanoparticle-catalyzed single-walled carbon nanotubes (SWCNTs) possess superparamagnetic properties, which enable them to be used as contrast agents in magnetic resonance imaging (MRI). Our study synthesized Gd-CNT for use as MRI contrast agents. Methods: To reduce the toxicity and solubility of CNTs, it was functionalized, and after loading with Gd was coated with polyethylene glycols (PEG). We then synthesized different concentrations of Gdn3+@CNTs-PEG and Gadovist® to be evaluated as MRI contrast agents. Results: The analysis showed that the Gd concentration in Gadovist® was 12.18% higher than synthesized Gdn3+@CNTs-PEG, but the mean signal intensity of the Gdn3+@CNTs-PEG was approximately 3.3% times higher than Gadovist®. Conclusions: Our findings indicate that synthesized Gdn3+@CNTs-PEG has the potential to be used as an MRI contrast agent in vitro, but in vivo assessment is necessary to determine the bio-distribution, kinetic, and signal enhancement characteristics.

Functional materials based on the crystalline allotropes of carbon have garnered tremendous interest from researchers in chemistry, physics, and material science for a long time. This paper reviews studies carried out on carbon black and graphite derivatives, their properties, and manufacturing applications. Graphite derivatives such as graphene, graphene oxide, reduced graphene oxide, expanded graphite, and graphene quantum dots are reviewed, along with a discussion of their synthesis and advantages. Generally, carbon black and graphite derivatives are incorporated into the polymeric material to enhance the performance of the end material. Recently, much attention has turned to the structural and electronic properties of carbon-based polymeric materials. Hence, at present, graphite-based polymeric material is the hottest topic in physics and materials science due to excellent electric and thermal conductivity, optical, mechanical properties, etc. The most common and widely used filler for rubber in the industry is carbon black due to its excellent physico-mechanical properties, thermal stability, oil resistance, etc. Therefore, carbon black and graphite derivatives incorporated composites of natural rubber have been reviewed in detail, along with a discussion of the current limitations and challenges of these exciting materials.

In the present study, the thermomechanical effects of adding a newly proposed nanoparticle within a polymer matrix such as polyethylene are being investigated. The nanoparticle is formed by a typical single-walled carbon nanotube (SWCNT) and two equivalent giant carbon fullerenes that are attached with the nanotube edges through covalent bonds. In this way, a bone-shaped nanofiber is developed that may offer enhanced thermomechanical characteristics when used as a polymer filler, due to each unique shape and chemical nature. The investigation is based on molecular dynamics simulations of the tensile stress–strain response of polymer nanocomposites under a variety of temperatures. The thermomechanical behavior of the bone-shaped nanofiber-reinforced polyethylene is compared with that of an equivalent nanocomposite filled with ordinary capped single-walled carbon nanotubes, in order to reach some coherent fundamental conclusions. The study focuses on the evaluation of some basic, temperature-dependent properties of the nanocomposite reinforced with these innovative bone-shaped allotropes of carbon.

Aluminium alloys and its composites are the most important engineering materials, which have been broadly utilized in Automobile and Aviation industries due to its properties like low density and good structural rigidity. Graphene is having the allotropes of carbon which are used as filler and perfect reinforcement for traditional materials used for structural applications.. This research is carried out to analyse the Al 6061 matrix micro composites with different reinforcement content of Graphene (0.25, 0.50, 0.80 weight %). The Ball M illing process is carried out to achieve uniform dispersion of the graphene and the mixtures were prepared by powder metallurgy (PM ). The prepared compacts are sintered by using the box furnace and microwave sintering. Hardness and green density are investigated for different types of sintering and Graphene weight fraction. Experimental results will give the dimension for the preparation of Al – Graphene composites considering the hardness and green density.

The many allotropes of carbon are of fundamental interest as thermoelectrics. Some can have very large Seebeck coefficients α (sometimes, the symbol S is used for thermoelectric power; it is the thermoelectric voltage, Vth, generated per K). The Seebeck coefficient tells us how large a voltage is generated, if one side of the sample is heated and the other side is cooled (“thermoelectric generator”). For example, single-walled carbon nanotubes (SWNTs) can have Seebeck coefficients as high as 60 μV/K and graphene up to 100 μV/K when subject to a gate voltage. Sometimes, large electrical conductivities σ can also be obtained with these two carbon materials (in aggregate mats) of the order: σ ~ 105 S/m depending on the morphology and doping.

For any given graph G , we say W ⊆ V G is a resolving set or resolves the graph G if every vertex of G is uniquely determined by its vector of distances to the vertices in W . The metric dimension of G is the minimum cardinality of all the resolving sets. The study of metric dimension of chemical structures is increasing in recent times and it has application about the topology of such structures. The carbon atoms can bond together in various ways, called allotropes of carbon, one of which is crystal cubic carbon structure CCC n . The aim of this article is to find the metric dimension of CCC n .

Carbon nanotubes (CNTs) are one of the most significant allotropes of carbon. They are made of sp2-hybridized carbon with a hollow cylindrical tube structure. Based on the number of concentric cylinders, they may be single-walled CNTs, double-walled CNTs, or multiwalled CNTs. Based on their configuration, CNTs are of three types: chiral, zigzag, and armchair. CNTs have outstanding physical properties such as high tensile strength, high electrical conductivity, and thermal, chemical, and mechanical stability. These physical properties can be increased by the functionalization and formation of composite materials. Large numbers of CNT composites have been documented in the literature with a wide range of applications. CNTs and their composite materials can be analyzed using different microscopic techniques such as scanning electron microscopy, atomic force microscopy, transmission electron microscopy with energy-dispersive X-ray analysis (EDAX), and EDAX mapping. In addition, Raman spectroscopy is one of the most powerful tools for characterizing CNTs and their composite materials. CNTs and their composite materials have a wide range of applications in the fields of composite materials, nanoelectronics, drug delivery, pharmaceuticals, electrocatalysis, sensing, fuel cells, supercapacitors, hydrogen storage, water purification, and so on. Without doubt, CNTs and their composite materials have outstanding properties with significant applications in almost every branch of science and technology.

Since the last 30 years, incredible amount of research has been performed toward finding novel, smart, and cost-effective materials for device applications. Carbon among other materials is one of the most versatile elements present in nature that can produce different allotropes due to the existence of its variable hybridizations. Moreover, graphene is being considered as the mother of other carbon allotropes as they are the structurally derived allotropes of different dimensionalities such as fullerene, graphene quantum dots (0-D), carbon nanotubes, nanohorns, nanofibers, graphene nanoribbon (1-D), graphene (2-D), graphite and diamond (3-D) and are being implemented for various device applications. The synthesis methodologies of these allotropes including arc discharge, laser ablation, and chemical vapor deposition (CVD) techniques are discussed in this chapter to produce 0-D, 1-D, and 2-D carbon allotropes. CVD is considered as the most reliable technique for bulk production of highly crystalline graphene and its derivatives, single-crystalline diamonds, CNTs, and aligned CNTs on certain pre-treated substrates which are beneficial for device applications. Further, solid-state synthesis approaches such as ball milling and annealing have been adopted to generate CNTs, while graphene and offshoots have been synthesized by employing wet milling, top-down, and bottom-up processes. Also, it is noteworthy to mention that the bottom-up processes have been proven to be more effective compared to the top-down approaches for device fabrications. Furthermore, allotropes of carbon are known to be functionalized with metal-based nanoparticles, biomolecules, etc. to generate smart materials in order to obtain high-performance devices.

Graphite, with many industrial applications, is one of the widely sought-after allotropes of carbon. The sp2 hybridized and thermodynamically stable form of carbon forms a layered structure with strong in-plane carbon bonds and weak inter-layer van der Waals bonding. Graphite is also a high-temperature ceramic, and shaping them into complex geometries is challenging, given its limited sintering behavior even at high temperatures. Although the geometric design of the graphite structure in many of the applications could dictate its precision performance, conventional synthesis methods for formulating complex geometric graphite shapes are limited due to the intrinsic brittleness and difficulties of high-temperature processing. Here, we report the development of colloidal graphite ink from commercial graphite powders with reproducible rheological behavior that allows the fabrication of any complex architectures with tunable geometry and directionality via 3D printing at room temperature. The method is enabled via using small amounts of clay, another layered material, as an additive, allowing the proper design of the graphene ink and subsequent binding of graphite platelets during printing. Sheared layers of clay are easily able to flow, adapt, and interface with graphite layers forming strong binding between the layers and between particles that make the larger structures. The direct ink printing of complex 3D architectures of graphite without further heat treatments could lead to easy shape engineering and related applications of graphite at various length scales, including complex graphite molds or crucibles. The 3D printed complex graphitic structures exhibit excellent thermal, electrical, and mechanical properties, and the clay additive does not seem to alter these properties due to the excellent inter-layer dispersion and mixing within the graphite material., 19 pages, 4 figures

The exploration of new two-dimensional (2D) allotropes of carbon has attracted great research attention after graphene, but experiment-feasible graphene allotropes with novel properties are still rare. Here, we predict a new allotrope of graphene, named Me-graphene, composed of both sp2- and sp3-hybridized carbon by topological assembly of C-(C3H2)4 molecules. With a transitional ratio of sp2- and sp3-hybridized carbon atoms (12 : 1) between those of graphene (1 : 0) and penta-graphene (2 : 1), Me-graphene has transition properties between those of graphene and penta-graphene, such as energy, band gap, and Poisson's ratio. Unusually, Me-graphene exhibits a near zero Poisson's ratio of from −0.002 to 0.009 in the xy-plane (or called “anepirretic”), different from that of graphene (0.169) and penta-graphene (−0.068). More importantly, the near zero Poisson's ratio behavior remains in a large strain range, being less than ±0.02 for strain from −15% to +3%. Me-graphene possesses an indirect band gap of 2.04 eV, as a transition of graphene (semimetal) and penta-graphene (wide band gap), and turns into a direct-bandgap semiconductor with an enlarged band gap of 2.62 eV under compressive strain. It possesses high hole mobility of 1.60 × 105 cm2 V−1 s−1 at 300 K. Me-Graphene has potential applications in electronic, photoelectric and high-speed mechatronic devices. The transitional properties related to the ratio of sp2- and sp3-hybridized carbon atoms are inspiring for searching for new graphene allotropes with combinational properties.

With an sp2-hybridized carbon atom structure, graphene is recognized as a nonlinear absorption (NLA) material, which has motivated scientists to explore new allotropes of carbon. Different from graphene, graphdiyne (GDY) consists of sp- and sp2-hybridized carbon atoms. An sp-hybridized carbon-carbon triple bond structure will bring in novel nonlinear optical properties, which are different from other allotropes of carbon. In this study, we investigated the broadband NLA properties (ultraviolet-infrared waveband) of GDY nanosheets, exfoliated using a liquid-phase exfoliation (LPE) method. The short ultraviolet cut-off wavelength (around 200 nm-220 nm) forebodes the potential application of GDY as an ultraviolet optical material. The outstanding NLA resulting in an ultraviolet waveband attests that the GDY nanosheets are veritable ultraviolet NLA materials, which have potential applications in ultraviolet optics. Our study broadens the application scopes of nanomaterials.

Graphite and diamond are two well-known allotropes of carbon with distinct physical properties due to different atomic connectivity. Graphite has a layered structure in which the honeycomb carbon sheets can easily glide, while atoms in diamond are strongly bonded in all three dimensions. The transition from graphite to diamond has been a central subject in physical science. One way to turn graphite into diamond is to apply the high pressure and high temperature (HPHT) conditions. However, atomistic mechanism of this transition is still under debate. From a series of large-scale molecular dynamics (MD) simulations, we report a mechanism that the diamond nuclei originate at the graphite grain boundaries and propagate in two preferred directions. In addition to the widely accepted [001] direction, we found that the growth along [120] direction of graphite is even faster. In this scenario, cubic diamond (CD) is the kinetically favorable product, while hexagonal diamond (HD) would appear as minor amounts of twinning structures in two main directions. Following the crystallographic orientation relationship, the coherent interface t-(100)gr//(11-1)cd + [010]gr//[1-10]cd was also confirmed by high-resolution transmission electron microscopy (HR-TEM) experiment. The proposed phase transition mechanism does not only reconcile the longstanding debate regarding the role of HD in graphite-diamond transition, but also yields the atomistic insight into microstructure engineering via controlled solid phase transition., Comment: 35 pages, 5 figures

Graphite and diamond are well-known allotropes of carbon. Since the latter is far more valuable than the earlier, the transformation of graphitic structures to diamond has been subjected to a large number of studies. The industrial production of diamond crystallites is currently achievable by applying either a combination of enormous external pressure and heat on graphite or graphite–catalyst systems, or detonation of explosive carbonaceous materials. In comparison with graphite, the conversion of carbon nanostructures into diamond can be more favorable due to the effect of the surface tension brought about by the nanometer-sized curvature of carbon nanomaterials. A more facile synthesis of diamond is based on the molten salt preparation of core–shell carbon nanostructures in molten salts using either graphite or CO2 as the feed materials, and subsequent heat treatment of the fabricated nanostructured materials at atmospheric pressures, far less severe conditions than conventional processes. This chapter reviews some of the main features of these processes.

Cancer is the second leading cause of death globally. Lung cancer and breast cancer are the most common types of cancer in men and women, respectively. Many strategies are used to target cancer such as surgery, chemotherapy, radiotherapy and immunotherapy. Immunotherapy is the latest addition to these strategies, but they also suffer from hypersensitive and allergic reactions. Lately nanoparticles have gained enormous interest in the nanomedicine due to their unique properties at the nanoscale level. These can be modified easily by biomolecules. Carbon is the extraordinary and most sought of material in the nano world. The beauty of the carbon to form covalent linkage with different orbital hybridization forms various nanoallotropes of carbon having different hybridization between C-C. Carbon is the basis of life on earth. Thus, these carbon nanomaterials are biocompatible. Earlier only diamond and graphite were the two known allotropes of carbon. But the discovery of fullerene (C60) in 1985 has opened a new avenue for the discovery of carbon nanoallotropes. Soon this was followed by the discovery of carbon nanotubes (CNTs) by Iijima.

We describe in detail the different steps involved in the construction of a carbon nanotube (CNT) field-effect transistor (CNTFET) based on a network of single-walled CNTs (SWCNTs), which can selectively detect toxic gases. Due to the absorption feature of the allotropes of carbon, they can be used to make different devices. Absorbing materials by CNTs can change its electrical properties, which can be used in manufacturing the chemical sensors. One specific type of electrochemical SWCNT sensors is the so-called CNTFETs. The operation principle of these sensors is based on the changes in the I–V curves of nanotubes as a result of adsorption of specific molecules on their surface.

Carbon nanotubes (CNTs) are allotropes of carbon with hollow, long structures, having diameters on the nanometer scale. They can be described as rolled-up graphene layers. During the last years, they have been increasingly used in the fields of pharmacy and biomedicine. However, due to their high hydrophobicity, they cannot be easily handled in most solvents of biological interest. To this end, different surfactants have been used to improve their dispersion in aqueous media. In the present work, we investigated the adsorption behavior of two surfactants, sodium dodecyl sulfate (SDS) and sodium dodecyl benzene sulfonate (SDBS), at different concentrations on a CNT surface by classical molecular dynamics (MD) simulations. Our results are presented in terms of distance between surfactant molecules and CNT surfaces, radial distribution functions and interaction energies. In all the models simulated in this work, a strong interaction of both surfactants with the CNT surface is observed, as it is demonstrated by decreasing distances between the surfactants and the CNT during simulation time, the shape of their radial distribution functions, as well as favorable adsorption processes from an energetic point of view. 2014/UEM14 2.318 JCR (2020) Q3, 116/162 Chemistry, Physical 0.406 SJR (2020) 135/394 Chemical Engineering (miscellaneous) No data IDR 2019 UEM

Mesostructured silica, dendrimers, and allotropes of carbon were exhaustively used in biomedical, cosmetics, semiconductors, and food industry applications. Considering the huge prospect of nanomaterials, their potential hazards on exposure to humans and their related ecotoxicological effects needs to be summarized. Nanoparticles with size below 100 nm could pass into the lung and then to blood through inhalation, ingestion, and skin contact. As nanotechnology innovation is expected to achieve $ 2231 million by 2025, humans will be exposed ever increasingly in day-to-day life and in industries. In this review, the latest synthetic methodology of silica, dendrimers, and CNTs, their biological applications (in vitro and in vivo) related to toxicity were discussed. In terms of structured silica, the toxic and non-toxic effect induced by specific templates (cetylpyridinium bromide, cetyltrimethylammonium bromide, dipalmitoylphosphatidylcholine, C16L-tryptophan, C16-L-histidine, and C16-L-poline) that are used to generate mesoporous silica, silica nanoparticle sizes (25, 50, 60, 115, and 500 nm), and silane functionalization (NH2 and COOH) were discussed. The recent applications of different generations (G3, G4, G5, and G6) of amphiphilic Janus dendrimers were discussed along with toxicity effect of different charged dendrimers (cationic and anionic) and effect of PEGylation. Recent synthesis, advantages, and disadvantages of carbon nanotubes (CNTs) were presented for structures like single walled carbon nanotubes (SWCNTs) and multiwalled carbon nanotubes (MWCNTs). The influence of diameter of SWCNTs (linear and short), thickness (thin and thick), effect of oxidation, metal oxide species (TiO2, Fe, and Au), and biocompatible polymers (polyethylene glycol, bisphosphonate, and alendronate) were shown in relation to molecular pathways in animal cells.

Graphene is one of the allotropes of carbon which possesses fascinating properties such as high surface area, planar structure, high chemical stability, greater electron mobility, and conductivity. Because of its fascinating properties, it has been considered as a promising supporting material to synthesize different functional materials for various applications. However, it has been used widely in metal oxide semiconductor photocatalysis for solar energy conversion and environmental remediation applications. Introduction of graphene as solid support along with semiconductor metal oxide photocatalysts greatly enhances the rate of photocatalytic reactions due to its high electron mobility and conductivity. During photocatalysis, the photogenerated electrons are rapidly migrated to graphene support from metal oxide photocatalysts owing to the conduction band work function matching of both metal oxides and graphene. In this chapter, we discuss and summarize the significant advances of grapheme-supported mixed metal oxides in different photocatalytic applications especially photocatalytic degradation of organic pollutants and H2 production.

The Aluminium metal components have proved their suitability in the field of aerospace industry, naval, sports, and other structural applications by their advantageous properties. Aluminum as base material has disadvantageous properties like high wear rate, less hardness which limits its application for distinguished applications. Carbon has unique characteristic of high strength and hardness due to four valance electrons (Tetra Valant) available for bonding. Diamond and Graphite are the two allotropes of carbon. Graphene is an allotropic form of carbon derived from graphite which exhibits high tensile strength, better co-efficient of friction and easily derivable material. Reinforcement of Graphene with Aluminium 6061improves the properties of base material and makes it more suitable for special applications. Surface hardness is one of the important properties required for applications where more wear is observed. Shock waves produced by blasting the membranes with high pressure and make them hit the surface of the specimen enhances the hardness of the material by strain hardening [1]. This paper focuses on discussion about the enhancement of surface hardness of Al6061t0 composed with various percentage of Graphene Hydroxyl.

Carbon is a unique chemical element whose different forms or allotropes are inexhaustible in number. It has been in use since antiquity and now, the possibility of manipulating the lattice structure of its crystalline allotropes, offers it unlimited advanced applications. This review aims at demonstrating certain aspects of engineering material in different applications. Various structures of some identified allotropes carbon, respective properties and uses of the allotropes were reviewed. Amorphous carbon materials find application mainly as fuels and sometimes as parent materials for synthesis of more useful chemicals. Their limited application was ascribed to their unstable irregular patterned structure which cannot be manipulated easily to meet further needs. Structurally, carbon exists in the sp3 and sp2 hybridized state in the crystal lattice of its crystalline allotropes. Due to the salient features of its allotropes, carbon finds application in energy generation and storage, optics, electronics, opto-electronics, electro-catalysis, corrosion control, bio-sensing (diagnostics), sensing, agriculture, water treatment, making of composite materials with unique properties and more. There is no limit to the application of carbon. It was recommended that renewable and sustainable alternative precursors for synthesis of carbon nanomaterials with crystal growth control be sought for.

In recent years, two-dimensional (2D) nanomaterials have received tremendous attention due to their unique structure and extraordinary properties. Graphene, silicene, germanene and stanene- the 2D allotropes of carbon, silicon, germanium and tin have been reported in last few years and their properties have been studied elaborately. Plumbene, the 2D allotrope of lead, is recently reported. It is analogous to graphene, silicene, germanene and stanene in single-layered and hexagonal arrangement of atomic structure. In this paper, molecular dynamics simulations have been carried out to study the effect of sample size, temperature and strain velocity on the mechanical properties of plumbene. The results show superior mechanical properties of the single layer plumbene sheet which is several times higher than bulk lead making it a suitable candidate for using as reinforcement to develop high strength nanocomposites.

Self-assembled synthetic hybrid materials are an important class of artificial materials with potential applications in various fields ranging from optoelectronics to medicine. The noncovalent interactions involved in the self-assembly process offer a facile way to create hybrid materials with unique and interesting properties. In this context, self-assembled hybrid materials based on carbon nanotubes (CNTs), graphene, and graphene derivatives such as graphene oxide (GO) and reduced graphene oxide (RGO) are of particular significance. These composites are solution processable, generally exhibit enhanced electrical, mechanical, and chemical properties, and find applications in the fields of light harvesting, energy storage, optoelectronics, sensors, etc. Herein, we present a brief summary of recent developments in the area of self-assembled functional hybrid materials comprising one-dimensional (1D) or two-dimensional (2D) carbon allotropes and synthetic π-systems such as aromatic molecules, gelators, and polymers. Functionalizing carbon allotropes with aromatic molecules is a promising way to realize hybrid materials with various applications. Carbon nanomaterials, such as two-dimensional graphene and one-dimensional carbon nanotubes, have already started to find uses in electronic and optoelectronic applications. Hybrid materials that combine these carbon nanostructures with small aromatic molecules or polymers can extend the range of applications further still. Ayyappanpillai Ajayaghosh from the CSIR-National Institute for Interdisciplinary Science and Technology and co-workers have reviewed the various approaches developed to combine these carbon allotropes with organic materials and thus create even more functional materials. They give an overview of the various solution-processed self-assembly methods used to create functional hybrid allotropes of carbon and their potential uses in novel light-harvesting systems, solar cells and organic field-effect transistors. Exploration of noncovalent interactions of such as H-bonding, p-stacking and van der Waals forces to the design of hybrid materials of 1D or 2D carbon allotropes and synthetic p-systems such as aromatic small molecules, gelators and polymers for various applications ranging from materials to biology are discussed.

Many studies have demonstrated the advantages of advanced materials in the field of wind turbine blades. Materials with certain desired properties like, low weight to reduce gravitational forces, high strength to withstand wind force and gravitational force of the blade, high fatigue resistance to withstand cyclic load, high stiffness to ensure stability of the optimal shape, are studied and reviewed in this paper. It is observed that Composites reinforced with Nano materials exhibit good mechanical properties, Carbon nanotubes are allotropes of carbon with a nanostructure that can have an aspect ratio greater than 1,000,000. These cylindrical carbon molecules have special properties that make them potentially useful in wind turbine blades. Carbon nano tubes can be reinforced with different types of resins to exhibit different properties, which is studied in this work and compared with existing materials used in wind turbine blades. Therefore, the objective of this study is to find a suitable material for wind turbine blade application.

Materials possessed with unexplored potential like, Graphene and other allotropes of Carbon has inexorably marched its way into the field of research. The distinct property of the Graphene includes elastic modulus (0.5 – 1 TPa), specific surface area (2630m 2 g −1 ), tensile strength 130 GPa and these properties are supreme compared to allotropes of carbon material such as Carbon Nano Tube (CNT), graphite etc. In order to make complete utilization of this astounding property, it is currently being used in the form of reinforcement to enhance the mechanical properties of the composites. The current study focuses on the addition of various combinations of Graphene and MWCNT in enhancing the mechanical and tribological performance of AA 2024 composites. The composite is processed through the ultrasonic liquid processor, ball milling followed vacuum hot press and hot extrusion. Raman analysis, SEM morphology of the reinforcements, micro hardness, X-ray diffraction analysis are done on developed composites. Further, dry frictional wear test was carried out using pin-on-disc tribometer to evaluate the effect of Graphene/CNT in the composites under various normal load and disc speed conditions. Thus obtained hardness, mass loss and friction coefficient values are compared to various combinations of reinforcements and AA 2024 alloy. Surface roughness values (Ra), Max peak (Rp) and Max valley (Rv) are found to be comparatively lower than the monolithic AA 2024 alloy.

In this paper, the synthesis of carbon nanowalls (CNWs) by the chemical vapor deposition method in the plasma of a radio frequency (RF) capacitive discharge is considered. The so-called “CNWs” are one of the allotropes of carbon, which are interesting from both the practical and theoretical points of view. Because of their large surface, CNWs are a perfect electrode material for electronic devices. CNWs were synthesized at relatively low values of RF power, and it was found that an increase in the discharge power caused a decrease in the height of CNWs and an increase in their thickness. The study of graphitization of the CNW structure showed that synthesized CNWs had a low number of defects in the structure. The obtained results could be useful for the low-cost production of CNWs by the plasma-enhanced chemical vapor deposition (PECVD) method.

A rigorous numerical optical band gap analysis is presented regarding the enhanced ultraviolet light transmission realized for barium-phosphate glasses melted with graphite, multi-wall carbon nanotubes, and nano-diamond powder. The study entails a comparative assessment wherein optimal ultraviolet transparencies were achieved. It is proposed that based on the principle of superposition, the optical absorption spectra of carbon-doped glasses may be considered as solid solutions of the host matrix and an optimal carbon-doped matrix with characteristic P O C bonds. 31P nuclear magnetic resonance (NMR) was employed for structural analysis to evaluate the relative content of the PO4 tetrahedra with two (Q2) and one (Q1) bridging oxygens. Further, the Q2/Q1 ratio from 31P NMR data was correlated with the Urbach energy. In the carbon-doped metaphosphate system, the widening of the band gap can be attributed to a decreased matrix polarizability, structurally promoted by decreased concentration of the non-bridging oxygens in agreement with the effects associated with decreased optical basicity of the matrix.