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In a wide range of technical applications, the need for strong yet lightweight materials has significantly increased. Allotropes of carbon are combinations of several elements that exist as crystals. The production of components using 3D printing commonly employs a variety of infill patterns to speed up printing with the use of less material. The proposed study entails employing the chosen 3D printing methods to analyze tensile specimens made from carbon allotropes. On 3D printed parts, the von-Mises stress has been predicted using a finite element simulation. As part of the simulation process, parts are prepared in solid modeling software and then put under tensile loads in ANSYS to determine the desired results. Three distinct materials namely carbon nanotubes (CNT), graphene, and carbon fiber polylactic acid composite (CF+PLA), and two infill patterns namely honeycomb and rectilinear have been investigated and compared, where it showed that CNT material with honeycomb infill pattern shows better results than graphene and CF+PLA. Additionally, the outcomes of simulation results are compared with CF+PLA specimen created with Creality Ender 3 fused deposition modeling (FDM) printer. The CF+PLA specimen was fabricated according to ASTM D638 having different process parameters. The findings revealed that the tensile strength of carbon allotropes with a honeycomb pattern is increased by 20% when compared to materials made of commercial CF+PLA with a rectilinear pattern. This improvement in strength is attributable to the lower void content and higher layer-to-layer bonding during this process which can improve the components for the aerospace and defense sectors. [ABSTRACT FROM AUTHOR]

Novel superhard tetragonal carbon allotropes C5, C6, and C7, characterized by the presence of sp3- and sp2-like carbon sites, have been predicted from crystal chemistry and extensively studied by quantum density functional theory (DFT) calculations. All new allotropes were found to be cohesive, with crystal densities and cohesive energies decreasing along the C5-C6-C7 series due to the greater openness of the structures resulting from the presence of C=C ethene and C=C=C propadiene subunits, and they were mechanically stable, with positive sets of elastic constants. The Vickers hardness evaluated by different models qualifies all allotropes as superhard, with Hv values ranging from 90 GPa for C5 to 79 GPa for C7. Phonon band structures confirm that the new allotropes are also dynamically stable. The electronic band structures reveal their metallic-like behavior due to the presence of sp2-hybridized carbon. [ABSTRACT FROM AUTHOR]

In this study, we present our findings from analyzing data contained in approximately 265,000 journal and patent publications in the field of carbon nanotube (CNT)-related research spanning the last two decades (2003 to 2023). The purpose of this study is to identify and extract prominent trends and establish connections, such as those between materials and applications. Using a natural language processing (NLP)-based analysis, we have identified over 80 emerging concepts across three major categories (applications, materials, and properties) in the field of CNTs, which is presented in a "Trend Landscape" map. While early research efforts appeared to focus on synthesis techniques (including the now well-established and dominant technique of chemical vapor deposition (CVD)), in recent years the field has been driven by an increase in interest in CNT composites, especially involving other nanoscale materials such as MXene and metal–organic frameworks (MOFs). High growth applications include the use of CNTs in energy storage and conversion technologies such as fuel cells, next-generation batteries, and nanogenerators, and in sensors including wearable human motion sensors. Investment data suggests commercial interest in development and use of CNTs in a variety of industry types, such as semiconductors, energy, and to a smaller extent the biomedical industry. The intent of this report is to serve as a useful guide to researchers to aid in further exploration of the field of CNT based materials and applications. [ABSTRACT FROM AUTHOR]

In this study, four new tetragonal sp3 carbon allotropes with high dynamic and mechanical stabilities (I41/acd-C112, I4/mcm-C128, I4/mcm-C112, and I41/amd-C64) were predicted using first-principles calculations. The I41/acd-C112, I4/mcm-C128, I4/mcm-C112, and I41/amd-C64 allotropes exhibited semiconductor behavior, as confirmed by their wide band gaps (calculated to be 3.80, 3.22, 3.56, and 3.51 eV, respectively) and superhardness, as evidenced through hardness and ideal strength calculations.

In this work, we investigate the electronic and magnetic properties of single-layer pentahexoctite, a two-dimensional carbon allotrope patterned by pentagons, hexagons, and octagons. Using density functional theory (DFT) calculations incorporating on-site and intersite Coulomb interactions, we find that type-II Dirac Fermions are formed by a nearly flat band intersecting with a dispersive band at the Fermi level. We further examine the physical origin of nearly flat bands of pentahexoctite. Constructing ab initio tight-binding Hamiltonian based on Wannier functions, we reveal that nearly flat bands of pentahexoctite originate from quantum-mechanical destructive interference. Remarkably, our DFT calculations including extended Hubbard interactions show that hole doping induces a ferrimagnetic phase transition driven by the enhanced density of states in the nearly flat band. This finding highlights that monolayer pentahexoctite is a promising candidate for pristine all-carbon magnetic materials to serve as a platform for future magnetic and spintronic devices. [ABSTRACT FROM AUTHOR]

This work investigates the structural, mechanical, and electrical properties of the superhard semiconductor carbon BC14 under pressure, based on density functional theory (DFT). BC14 formed by sp3 hybridization still maintains good mechanical stability and dynamic stability under 100 GPa pressure. The relative enthalpy of BC14 increases gradually at a slower rate and is always much lower than that of BC12, C96, T-carbon, TY-carbon, and Y-carbon. The elastic constant, elastic modulus, and ratio of bulk modulus (B) to shear modulus (G) increase with pressure, while the hardness exhibits a decreasing tendency. BC14 is anisotropic in elastic mechanics, and its Young's modulus (E) is isotropic in the (111) direction. Increasing pressure leads to the anisotropy of elastic modulus becoming stronger. From 0 GPa to 100 GPa, the band gap increases from 5.56 eV to 6.07 eV, and inherits indirect characteristics. No obvious effect of pressure is observed with regard to the number of diffraction peaks in the XRD pattern, but the diffraction peaks are slightly shifted. [ABSTRACT FROM AUTHOR]

Novel superhard tetragonal carbon allotropes C5, C6, and C7, characterized by the presence of sp3- and sp2-like carbon sites, have been predicted from crystal chemistry and extensively studied by quantum density functional theory (DFT) calculations. All new allotropes were found to be cohesive, with crystal densities and cohesive energies decreasing along the C5-C6-C7 series due to the greater openness of the structures resulting from the presence of C=C ethene and C=C=C propadiene subunits, and they were mechanically stable, with positive sets of elastic constants. The Vickers hardness evaluated by different models qualifies all allotropes as superhard, with Hv values ranging from 90 GPa for C5 to 79 GPa for C7. Phonon band structures confirm that the new allotropes are also dynamically stable. The electronic band structures reveal their metallic-like behavior due to the presence of sp2-hybridized carbon.

Malwina Sosnowska,1 Marta Kutwin,1 Piotr Koczoń,2 André Chwalibog,3 Ewa Sawosz1 1Department of Nanobiotechnology, Institute of Biology, Warsaw University of Life Sciences, Warsaw, Poland; 2Department of Chemistry, Institute of Food Sciences, Warsaw University of Life Sciences, Warsaw, Poland; 3Department of Veterinary and Animal Sciences, University of Copenhagen, Frederiksberg, DenmarkCorrespondence: André Chwalibog, Department of Veterinary and Animal Sciences, University of Copenhagen, Frederiksberg, Denmark, Tel +45 40963573, Email ach@sund.ku.dkBackground: The various growth factors change the phenotype of neoplastic cells from sedentary (epithelial) to invasive (mesenchymal), which weaken intercellular connections and promote chemotaxis. It can be assumed that the use of anti-inflammatory polyhydroxyfull nanofilms will restore the sedentary phenotype of neoplastic cells in the primary site of the tumor and, consequently, increase the effectiveness of the therapy.Methods: The studies were carried out on liver cancer cells HepG2, C3A and SNU-449, and non-cancer hepatic cell line THLE-3. Transforming growth factor (TGF), epidermal growth factor and tumor necrosis factor were used to induce the epithelial–mesenchymal transition. C60(OH)40 nanofilm was used to induce the mesenchymal–epithelial transition. Obtaining an invasive phenotype was confirmed on the basis of changes in the morphology using inverted light microscopy. RT-PCR was used to confirm mesenchymal or epithelial phenotype based on e-cadherin, snail, vimentin expression or others. Water colloids at a concentration of 100 mg/L were used to create nanofilms of fullerene, fullerenol, diamond and graphene oxide. The ELISA test for the determination of TGF expression and growth factor antibody array were used to select the most anti-inflammatory carbon nanofilm. Mitochondrial activity and proliferation of cells were measured by XTT and BrdU tests.Results: Cells lost their natural morphology of cells growing in clusters and resembled fibroblast cells after adding a cocktail of factors. Among the four allotropic forms of carbon tested, only the C60(OH)40 nanofilm inhibited the secretion of TGF in all the cell lines used and inhibited the secretion of other factors, including insulin-like growth factor system. Nanofilm C60(OH)40 was non-toxic to liver cells and inhibited the TGF-β 1/Smad pathway of invasive cells treated with the growth factor cocktail.Conclusion: The introduction of an anti-inflammatory, nontoxic component that can induce the mesenchymal–epithelial transition of cancer cells may represent a future adjuvant therapy after tumor resection.Graphical Abstract: Keywords: carbon allotropes, epithelial phenotype, growth factors, hepatocellular carcinoma, mesenchymal phenotype, metastasis

ABSTRACT3D printing has become a powerful technique in electrochemistry for fabricating electrodes, thanks to readily available conductive nanocomposite filaments, such as those based on carbon fillers (i.e., carbon nanotubes (CNTs) or carbon black (CB)) within an insulating polymeric matrix like polylactic acid (PLA). Inspired by inorganic heterostructures that enhance the functional characteristics of nanomaterials, we fabricated hetero-layered 3D printed devices based on carbon allotropes using a layer-by-layer assembly approach. The heterolayers were customised through the alternate integration of different carbon allotrope filaments via a multi-material 3D printing technique, allowing for a time-effective method to enhance electrochemical performance. As a first demonstration of applicability, CNT/PLA and CB/PLA filaments were utilised to construct ordered hetero-layered carbon-based electrodes. This contrasts with conventional methods where various carbon species are mixed in the same composite-based filament used for building electrochemical devices. Multi-material 3D-printed carbon electrodes exhibit improved electrochemical performance in energy conversion (e.g., hydrogen evolution reaction or HER) and sensing applications (e.g., ascorbic acid detection) compared to single-material electrodes. This work paves the way for manufacturing advanced 3D-printed heterolayered electrodes with enhanced electrochemical activity through multi-material 3D printing technology.

The applications of carbon allotrope-reinforced Ti-based composites have witnessed enormous expansion in recent times owing to their light weight and competitive properties. However, a consistent controversy still exists on the process of in-situ TiC formation (during powder preparation, reinforcement dispersion and synthesis), its site within the composite and particularly the role it plays on the properties of the bulk composite. Although some authors have opined that the presence of TiC in the bulk composite enhances its overall properties, others hold a contrary opinion. Hence, this current study is aimed at reviewing the positions of the previous studies on this seemingly controversial subject up to date; with a view to broadening the available knowledge base on this crucial area of interest. [ABSTRACT FROM AUTHOR]

The inherent qualities of carbon nanosheets that come from their underlying molecular structure have drawn an enormous amount of interest from researchers. Molecular descriptors are commonly used graph-theoretic metrics to analyze the physicochemical properties of a molecule based on its molecular structure. Our current research validates the use of molecular descriptors in studying three recently developed carbon allotropes: pentagraphene, phagraphene, and phographene. These allotropes have significant thermal, dynamic, and mechanical stabilities that are comparable to graphene. General analytical expressions for both degree and neighborhood degree sum-based indices of these nanosheets are derived through the utilization of graph theoretical methods. Following a filtering process of the significant indices, regression models that accurately predict atomic density, specific heat capacity and total π-electron energy of carbon allotropes are developed. Additionally, Shannon entropy is introduced as an information index, which can be utilized for predictive studies in the future and as a tool for comparing structural complexity by incorporating topological index in its definition.

Background: The various growth factors change the phenotype of neoplastic cells from sedentary (epithelial) to invasive (mesenchymal), which weaken intercellular connections and promote chemotaxis. It can be assumed that the use of anti-inflammatory polyhydroxyfull nanofilms will restore the sedentary phenotype of neoplastic cells in the primary site of the tumor and, consequently, increase the effectiveness of the therapy.Methods: The studies were carried out on liver cancer cells HepG2, C3A and SNU-449, and non-cancer hepatic cell line THLE-3. Transforming growth factor (TGF), epidermal growth factor and tumor necrosis factor were used to induce the epithelial–mesenchymal transition. C60(OH)40 nanofilm was used to induce the mesenchymal–epithelial transition. Obtaining an invasive phenotype was confirmed on the basis of changes in the morphology using inverted light microscopy. RT-PCR was used to confirm mesenchymal or epithelial phenotype based on e-cadherin, snail, vimentin expression or others. Water colloids at a concentration of 100 mg/L were used to create nanofilms of fullerene, fullerenol, diamond and graphene oxide. The ELISA test for the determination of TGF expression and growth factor antibody array were used to select the most anti-inflammatory carbon nanofilm. Mitochondrial activity and proliferation of cells were measured by XTT and BrdU tests.Results: Cells lost their natural morphology of cells growing in clusters and resembled fibroblast cells after adding a cocktail of factors. Among the four allotropic forms of carbon tested, only the C60(OH)40 nanofilm inhibited the secretion of TGF in all the cell lines used and inhibited the secretion of other factors, including insulin-like growth factor system. Nanofilm C60(OH)40 was non-toxic to liver cells and inhibited the TGF-β 1/Smad pathway of invasive cells treated with the growth factor cocktail.Conclusion: The introduction of an anti-inflammatory, nontoxic component that can induce the mesenchymal–epithelial transition of cancer cells may represent a future adjuvant therapy after tumor resection. [ABSTRACT FROM AUTHOR]

Hexagonal carbon allotropes C6, C9, and C12 with qtz, sta and lon topologies, respectively, were predicted on the basis of crystal chemistry and first principles (DFT) calculations. The new allotropes are mechanically (elastic properties) and dynamically (phonons) stable phases and are characterized by ultra-high Vickers hardness, exceptionally high for qtz C6 and C12, close to the previously studied qtz C3. The electronic band structures of all new allotropes show semi-conducting to insulating behavior. lon C12 can be considered as novel "superlonsdaleite." [ABSTRACT FROM AUTHOR]

All-carbon nano-heterostructure photodetectors based on different carbon allotropes demonstrate excellent photoelectric performance due to their ultrahigh carrier mobility, excellent optoelectronic properties, and strong interfacial coupling effects. However, the further improvement of device performance is still limited by the interfacial charge transfer and the large dark current of graphene. Herein, asymmetric all-carbon nano-heterostructures have been designed as active channels to fabricate C60/graphene/single-walled carbon nanotube (SWCNT) heterojunction photodetectors. With an optimal C60 thickness of 35 nm, the asymmetric C60/graphene/SWCNT photodetector exhibits excellent broadband photoelectric response from the visible to NIR range (405–1064 nm) with a high responsivity of 4568 A W–1 @ 940 nm, an ultrahigh detectivity of 3.56 × 1014 Jones @ 940 nm, and a fast response time of 2.57 ms. Importantly, the interfacial charge transfer mechanism has been for the first time investigated by combining Raman shift statistics, absorption spectra, and fluorescence lifetime with photoluminescence spectra at room temperature. Our results demonstrate that the asymmetric channel structure effectively promotes the separation and transfer efficiency of photogenerated carriers, thus enhancing the photoelectric performance of photodetectors. This work not only gives a method to characterize the interfacial charge transfer in carbon-based heterostructures but also provides a strategy to design and fabricate high-performance all-carbon nano-heterostructure photodetectors. [ABSTRACT FROM AUTHOR]

Al and its alloys are studied extensively for hydrogen generation through water splitting. Alloying Al with metal activators such as bismuth, indium, gallium, etc., leads to the formation of micro galvanic cells during hydrolysis reaction, resulting in an improved hydrogen generation rate. Activation of Al by adding carbon-based materials such as graphite, carbon nanotubes (CNTs), graphene, etc., can instantaneously generate hydrogen at room temperature. When carbon particles are desorbed from the Al matrix during hydrolysis, new Al is exposed, resulting in an increased reaction rate. In Al-Graphite composites which form core-shell structures, H 2 O molecules penetrate through the graphite layers and break down the core-shell structure during hydrolysis, and the new Al surfaces are exposed to water. It was found that Al with nano bismuth and graphene nanosheets showed better hydrogen generation rate and hydrogen yield. Graphene nanosheets control the agglomeration of Al and enhance the specific surface area for hydrolysis. During the hydrolysis of Al-CNTs composites, CNTs act as a cathode, resulting in galvanic corrosion between CNTs and the Al matrix. CNTs can also effectively control the agglomeration of Al during ball milling. Spark plasma sintered Al–Bi-CNT composites showed an enhanced hydrogen generation rate during hydrolysis. This paper presents an overview of hydrogen generation by hydrolysis of Al and its alloys, emphasising the addition of carbon-based materials such as graphite, graphene, CNTs, etc. • Activation methods to promote Al hydrolysis for hydrogen generation are discussed. • Hydrolysis of Al alloys with the addition of carbon-based materials are presented. • Carbon-based materials effectively control the agglomeration during milling. • Various hydrolysis reaction mechanisms are discussed in detail. • Using biomass-derived carbon as an additive to Al alloys could be a future research focus. [ABSTRACT FROM AUTHOR]

The most recent data on experimentally undiscovered carbon allotropes, predicted by the Density Function Theory (DFT), are reviewed. Classic carbon allotropes, graphenes, carbon nanotubes, fullerenes and their hybrids are being studied using DFT and related methods, resulting a host of potentially existing forms based on 5‐, 6‐, 7‐member cycles and their distinct combinations. Also known are cyclocarbons and large carbon clusters, nanobelts and nanoribbons, liquid, metallic, semiconductive and superhard carbons, which could exist under high or low pressures. These carbon allotropes can contain C atoms in the same hybridization state or be as their mixture, for example sp2+sp3. For several carbon allotropes, possible synthesis methods, properties and applications are proposed. [ABSTRACT FROM AUTHOR]

A novel approach is proposed for the description of possible reconstructive solid‐state transformations, which is based on the analysis of topological properties of atomic periodic nets and relations between their subnets and supernets. The concept of a region of solid‐state reaction that is the free space confined by a tile of the net tiling is introduced. These regions (tiles) form the reaction zone around a given atom A thus unambiguously determining the neighboring atoms that can interact with A during the transformation. The reaction zone is independent of the geometry of the crystal structure and is determined only by topological properties of the tiles. The proposed approach enables one to drastically decrease the number of trial structures when modeling phase transitions in solid state or generating new crystal substances. All crystal structures which are topologically similar to a given structure can be found by the analysis of its topological vicinity in the configuration space. Our approach predicts amorphization of the phase after the transition as well as possible single‐crystal‐to‐single‐crystal transformations. This approach is applied to generate 72 new carbon allotropes from the initial experimentally determined crystalline carbon structures and to reveal four allotropes, whose hardness is close to diamond. Using the tiling model it is shown that three of them are structurally similar to other superhard carbon allotropes, M‐carbon and W‐carbon. [ABSTRACT FROM AUTHOR]

Emerging technology and modernization have become a worldwide threat to human life in all aspects. Worldwide, all countries are in the race to develop the most advanced electronic devices and gadgets as they reflect the country's superiority and economic development. Specialists have forecasted that during and after the pandemic, the addiction toward modern gadgets have increased by 40% among the people irrespective of age. A few researchers have reported that the world economy is dependent on and dominated by countries manufacturing semiconductors, mobiles, electronic chips, and so on. People started sensing that modern devices are like a boon, as their lives seem to be more connected and comfortable with all their needs and wants being fulfilled at their doorsteps. But this boon is slowly whirling as a severe threat to human lives. Due to this rapid usage of electronic devices, electromagnetic interference (EMI) is drastically growing, which is considered a global warning issue for commercial and biological systems. So advanced countries have decided to make EMI shielding a compulsory entity to be implemented in all advanced electronic devices. Though traditional materials like metals and carbon allotropes have excellent shielding properties, they cannot cope with today's mass production of modern devices. Thus, researchers had to find a suitable substitute material that should possess properties such as sustainability and biocompatibility to overcome problems faced by the conventional materials. Thus, polymers have come into the world of EMI shielding applications. Polyvinylidene fluoride (PVDF), a non‐conductive polymer from the family of Fluorocarbons, is creating history in the field of EMI shielding applications. PVDF astonished researchers with its versatile features, such as light weight, flexibility, and easy processibility with excellent dielectric and piezoelectric properties. Though they are poor in electrically conductive properties, incorporating metals, carbon allotropes, and metal oxides as fillers make them superior to the existing conventional materials. Thus, the main objective of this review article is to highlight the uniqueness of PVDF as an advanced polymer for EMI shielding applications. It has been noted that PVDF is more suitable for EMI shielding in X, K, and Ku band frequencies. But overall, we noticed that the performance of PVDF has a great impact by incorporating a combination of metal and carbon allotrope enhances the shielding effectiveness up to 65 dB in the Ku‐band (Kurz‐under) frequency band range of (12–18 GHz). [ABSTRACT FROM AUTHOR]

In this work, initial stage of diamond growth at 300℃ by hot filament chemical vapor deposition (HFCVD) was studied using a single layer graphene membrane for transmission electron microscopy (TEM) observations. The graphene membrane was exposed to a temperature of 300℃, 60 mm below the hot filament, for 1 s, 10 s, 30 s, 120 s, and 30 min at 20 Torr with a gas mixture of 1% CH4–99% H2. Under this condition, only the gas phase is stable at 300℃. As the exposure time increases, the average size of nanocarbon particles also increases. The growth of nanoparticles at 300℃, where only the gas phase is stable, indicates that the growth occurred by non-classical crystallization, where the building blocks are nanoparticles. At 1 and 10 s, only i-carbon nanoparticles were captured, whereas the hexagonal diamond and n-diamond ones were additionally captured at 30 and 120 s. A cubic diamond nanoparticle was captured only at 30 min. The structural stability of nanocarbon changes depending on the size, in the order of amorphous, i-carbon, hexagonal diamond, n-diamond, and cubic diamond, as the size increases. Observed n-diamond nanoparticles have a core-shell structure surrounded by an i-carbon layer. I-carbon nanoparticles larger than ~ 10 nm had a polycrystalline structure, whereas hexagonal diamond and n-diamond nanoparticles had a single crystal structure. A lattice of the i-carbon layer in contact with n-diamond nanoparticles was partially oriented in the same direction as that of the n-diamond nanoparticles. [ABSTRACT FROM AUTHOR]

Described are the first two molecular designs of the triply periodic Schwarz P surface using merely the Schläfli t{3,7} pattern of sp2‐hybridized carbon atoms. Each atom is exactly part of one heptagon and two hexagon rings so that two heptagons do not share the same edge or vertex. Such pattern, called hyperbolic soccer ball obeys the isolated‐heptagon rule with the minimum possible number of hexagons between heptagons similar to the isolation of pentagons from hexagons in the C60 fullerene. Both of the designed P surfaces are unbalanced, that is, they have two unequal sides, and belong to space groups P432 of the cubic system, and P4/ncc of the tetragonal system, respectively. Unit cells have a multiple of 24 heptagons similar to the only one previously known in literature Schwarzite with the hyperbolic soccer ball pattern—the D surface of Vanderbilt and Tersoff. The geometry of the periodic structures and unit cell parameters were fully optimized by DFT calculations using CASTEP software with PBE and PBESOL functionals under generalized gradient approximation. The effect of P and D surface dilution by hexagons on the calculated density, elastic and electronic properties is discussed. [ABSTRACT FROM AUTHOR]

The right part of the Fe3C–100% C diagram has a certain incompleteness and fragmentation of the phase structure, which is associated with the impossibility of obtaining and studying alloys containing more than 5.0% C using known metallurgical smelting technologies under normal conditions. In this paper, three groups of problems are considered in the study of the right side of the Fe3C–100% C diagram. The first group of problems includes the absence of a sufficiently voluminous line of iron carbides on the diagram: FeC, Fe2C (except for Fe3C), Fe3C2, Fe4C, Fe5C2, Fe6C, Fe7C3, Fe8C, Fe20C9, Fe23C6. From this group of carbides, in addition to cementite θ-Fe3C, only three significant types of carbides are objectively distinguished: ε-carbide Fe2C, Hegg carbide χ-Fe5C2 and Ekström–Adcock carbide æ–Fe7C3, located to the right of the cementite line in chemical composition and not displayed on the Fe3C–100% C state diagram as full phases or diagram components, which are considered by default to be metastable, transitional phases. The absence of these carbides on the Fe3C–100% C diagram is explained by the fact that they cannot be obtained by metallurgical methods through the iron-graphite alloying and, therefore, their complete physicochemical and metallographic study can not be carried out with the subsequent introduction of the corresponding phase equilibrium fields into the Fe3C–100% C state diagram. The second group of problems is the fact that the "liquid–vapor" phase equilibrium area of the Fe–100% C diagram is currently not scientifically convincing, has not been studied, and no attempts have been made to study it. The third group of problems is that carbon as the main component of Fe–100% C alloys is currently considered as a pure graphite chemical in general with a "crystalline hexagonal layered lattice". It has been established that the structure of graphite inclusions in gray and high-strength cast iron does not correspond to an ideal hexagonal layered graphite lattice, but to a turbostratic, chaotic one. It is also shown that when assessing the graphite crystallization, the cast iron melt should be considered as a single-phase system in the form of a carbon-iron polymer, the structural basic elements of which are fullerenes and carbon nanoparticles based on them. The use of carbon allotropes to explain the problems of graphite structure formation is considered. It is proposed to designate the existing graphite line on the Fe3C–100% C diagram as a line of atomic carbon—Catom. [ABSTRACT FROM AUTHOR]

Numerous studies have been performed on different aspects of the mechanical behavior of polymer nanocomposites; however, the results obtained still lack a comprehensive comparative analysis of the mechanical properties of composites containing nanofillers of different shapes and concentrations and subjected to different static and dynamic loads. Carbon nanofillers were shown to provide the most significant improvement in the elastic properties of polymer composites. In this paper, we present a comparative analysis of the mechanical properties of polystyrene-based nanocomposites filled with carbon allotropes of different shapes: spherical fullerene particles, filamentary multi-walled nanotubes, and graphene platelets, fabricated by the same technology. The influence of shape and concentration of dispersed carbon fillers on mechanical and viscoelastic properties of composites in different stress–strain states was evaluated based on the results of tensile and three-point bending tests, and ultrasonic and dynamic mechanical analysis. Comparison of the static and dynamic elastic properties of nanocomposites allowed us to analyze their variations with frequency. At low concentrations of 0.1 wt% and 0.5 wt% all nanofillers did not provide significant improvement of elastic characteristics of composites. More efficient reinforcement was observed at the concentration of 5 wt%. Among the filler types, some increase in composite rigidity was observed with the addition of filamentary particles. The introduction of the layered filler provided the most pronounced rise in the composite rigidity. The weak frequency dependence of the mechanical loss tangent, which is characteristic of amorphous thermoplastics, was demonstrated for all the samples. [ABSTRACT FROM AUTHOR]

The influence of surface charge on tribo-layer is a crucial parameter in improving the performance of triboelectric nanogenerators (TENG). Nevertheless, most researchers focus on the structure and design of TENG rather than increasing the surface charge density, which is the main parameter for energy harnessing in nanogenerators. Herein, we tweaked the surface charge density of polydimethylsiloxane (PDMS) via incorporating different types of carbon allotropes to shift the charge density (positive to negative and vice versa) for high output TENG. The PDMS/GO TENG device generated a voltage of 234 V; higher compared to that of bare PDMS and other nanocomposite films, which is attributed to the high surface charge of PDMS/GO confirmed via Kelvin probe force microscopic (KPFM) analysis. As a proof concept, we have demonstrated the use of PDMS/GO-based TENG device for self-powered humidity sensor. [Display omitted] [ABSTRACT FROM AUTHOR]

3D printing has become a powerful technique in electrochemistry for fabricating electrodes, thanks to readily available conductive nanocomposite filaments, such as those based on carbon fillers (i.e., carbon nanotubes (CNTs) or carbon black (CB)) within an insulating polymeric matrix like polylactic acid (PLA). Inspired by inorganic heterostructures that enhance the functional characteristics of nanomaterials, we fabricated hetero-layered 3D printed devices based on carbon allotropes using a layer-by-layer assembly approach. The heterolayers were customised through the alternate integration of different carbon allotrope filaments via a multi-material 3D printing technique, allowing for a time-effective method to enhance electrochemical performance. As a first demonstration of applicability, CNT/PLA and CB/PLA filaments were utilised to construct ordered hetero-layered carbon-based electrodes. This contrasts with conventional methods where various carbon species are mixed in the same composite-based filament used for building electrochemical devices. Multi-material 3D-printed carbon electrodes exhibit improved electrochemical performance in energy conversion (e.g., hydrogen evolution reaction or HER) and sensing applications (e.g., ascorbic acid detection) compared to single-material electrodes. This work paves the way for manufacturing advanced 3D-printed heterolayered electrodes with enhanced electrochemical activity through multi-material 3D printing technology. [ABSTRACT FROM AUTHOR]

Chemical graph theory assumes an imperative part in displaying and planning any chemical structure or chemical network. The molecular structure of a chemical molecule strongly relates to its properties. The graphs that make up the molecular structure are made up of units known as vertices, and the covalent bonds that connect them are known as edges. The topological indices of any chemical compound can be used to better understand the chemical structure and its biological characteristics. In this study, the degree‐based multiplicative topological indices of the crystalline structure of cubic carbon (CCS) for levels m = 3–10 are computed, CCS[m] being one of the precious carbon allotropes. [ABSTRACT FROM AUTHOR]

Low-dimensional materials with a negative Poisson's ratio (NPR) have attracted lots of attention for their potential applications in aerospace, defense, etc. Although graphene and monolayer h-BN have been reported to have NPR behavior under external strains, the mechanism is not clear, and the critical strains of the occurrence of a NPR are relatively larger. Here, we propose that the origination of the NPR phenomena in the 2D honeycomb structures can be explained by the variation of the zigzag chains under strains. Our calculations clarify that a NPR occurs along the armchair-chain direction rather than the zigzag-chain direction in these materials. Furthermore, a series of two-dimensional carbon networks including zigzag chains have demonstrated that there is NPR phenomena in them. In some of the networks, a NPR can be found under a small external strain. Our study not only deepens the understanding of the origin of NPR in honeycomb systems but also offers guidance to design auxetic nanostructures. [ABSTRACT FROM AUTHOR]

Magnetic metal-carbon nanocomposites (MMCN) are emerging as sustainable materials, consisting of magnetic metals or alloys and carbon-based materials like CNT, graphene (Gr), carbon fiber (CF), and activated carbon. These materials possess unique magnetic properties that depend on various factors, such as preparation conditions, metal content, and phase composition. Incorporating carbon-based materials into magnetic metals has been observed to enhance their magnetic properties, including magnetic strength and moment. Researchers employ a range of tests to characterize these materials, such as FTIR, XRD, FESEM, TEM, BET, and VSM. Carbon-based materials such as CNT, graphene, etc., have been used as filler materials to reinforce the metal matrix because of their sustainability, tendency to integrate, and low cost. Further, they enhance the tribological performance and mechanical strength, provide corrosion resistance and improve electrical and thermal properties. Additionally, the addition of filler magnetic material in single or hybrid form into the carbon matrix increases the scope of application of MMCN. These composites are widely used in the application of biomedical, semiconductors, tribology, fuel cells, etc. In the present study, a comprehensive review has been carried out to provide a view of the fabrication aspect of the MMNC and to understand the role of the reinforcement method used to fabricate the composites. Finally, it covers different uses of the MMCN, which can lead to an eco-friendly environment.

The use of natural resources and their derivatives is gaining massive courtesy because of the growing demand for green chemistry. The present perspective features the challenges and opportunities of using carbohydrate polymer-modified carbon allotropes (CPMCAs) as nanofillers in reinforced polymer-composite coatings. CPMCAs can be regarded as an eco-friendly as well as a cost-effective approach and they are flattering ideal substitutes for traditional toxic nanofibers. They are associated with many essential features such as high surface area, uniform distribution, self-healing properties, high durability, long-term protection, optimized hydrophilicity, etc. that make them ideal substitutes. The anticorrosive potential gets magnified in CPMCAs as carbon allotropes prevent the diffusion of corrosive species and carbohydrate polymers prevent their galvanic coupling with the metal/alloy surfaces. CPMCAs successfully fulfil the requirements of self-healing or self-repairing coatings and provide long-term protection and self-healing properties for long exposure. The inhibition action of CPMCAs and self-healing have also been described.

Anthropogenic activity in terms of urbanization, industrialization, and modern agricultural techniques challenges the natural environment in terms of compromise in air pollution and water quality, which lead to hazardous health impacts on human beings. In this context, it is very essential to monitor the air and water quality to a maximum possible extent with maximum accuracy, which is of utmost significance. A significant effect on human health due to pollutants makes their detection in water and air essential. Even though various techniques of monitoring these pollutants are available, proven advantages of electrochemical techniques attract more attention. Because of this, an attempt is made to review some of the latest advances in electrochemical sensing of environmental contaminants, which include heavy-metal ions and pesticides. Electrochemical sensing has been done by using sensors designed with various materials. However, sensors designed with carbon and its allotropes such as carbon nanotubes, graphene derivatives, carbon nanodots, active carbon, screenprinted carbon electrode, and others are reviewed. Even though these sensors are capable of being used in medical analysis, food safety, soil quality, drug detection, etc., the review paper highlights only applications related to environmental monitoring. This review is mainly meant to come up with an understanding of the present-day progress in electrochemical applications based on carbon and its allied materials towards environmental pollutants. This review highlights some of the synthesis techniques of graphene (an allotrope of carbon) and sensor designing along with their performance. This review has established the compatibility in the published literature that graphene and related materials play a significant role in electrochemical sensing of pollutants. [ABSTRACT FROM AUTHOR]

The energy crisis is at the top of global priorities. It left us with an option to progress with highly efficient materials for energy conversion, production, and storage systems. Carbon nano-allotropes have more accessible, and modifiable surface with excellent surface area, conductivity, catalytic activity, and other features. Biochar synthesized from renewable organic materials such as plants and animal waste, have beneficial physicochemical features (surface functionalities, porosity, adsorption capacity, etc.) and agronomic properties. They are influenced by several factors like the type of thermal treatment and feedstocks. Modification of biochar is an excellent option to obtain synergistic effects and sustainable materials. The current comprehensive review article will focus on biochar, selected nanocarbons (fullerene, carbon dots, nanotubes, nanodiamonds, graphene, and graphdiyne), and their hybrids for hydrogen evolution. Particular emphasis will be on biochar as these materials could be easily generated from different wastes. Biochar can have graphitized or non-graphitized carbon atoms. They can have carbon fragments resembling fullerene. This can be a potential low cost biocarbon alternative to graphene and fullerene and we are well aware of the importance of graphene and fullerene. Future projections in this paper may lead to an added foundation for "trash to treasure"/ "waste to wealth" and "waste to fuel" research and also contributes towards real-world applications in the clean fuel and sustainable energy sector. • Carbon-based materials for H 2 generation using different techniques. • Particular emphasis on the biochar production, structure, and its application in the H 2 generation. • Fulfilling the gap using both carbon nanoallotropes and biochar in the energy production sector. • A comparative study between biochar and other carbon allotropes in terms of H 2 production efficiency. • Biochar has bright, green future in the domain of hydrogen production. [ABSTRACT FROM AUTHOR]

Using carbon composites for efficient atmospheric water harvesting and solar thermal conversion presents a promising approach to the persistent issue of water shortage. Recent research has concentrated on the application of various carbon-based materials, including carbon nanotubes (CNTs), graphene, graphene oxide (GO), reduced graphene oxide (rGO), carbon black, and mesoporous carbon, for both moisture capture and photothermal purposes. Integrating these materials with hygroscopic salts, metal-organic frameworks (MOFs), polymer composites, or hydrogels has been proposed to enhance water adsorption and release. This review comprehensively summarises the diverse carbon-based materials utilised as effective solar-driven atmospheric water harvesters. Additionally, it offers a comparative analysis of the efficacy of different carbon-based moisture adsorbents and discusses the challenges and limitations associated with using carbon-based materials for moisture adsorption and solar-powered desorption in atmospheric water harvesting. The review also discusses potential future research paths in this field. [Display omitted] • 10 % of the world's freshwater resources (13,000 km3) are in the Earth's atmosphere. • Atmospheric water harvesting enables sustainable water production over a broad spectrum of relative humidity levels. • The carbon composites assist highly efficient AWH, through a dual role as water vapor and solar absorbers. • The carbon composites are paving the way for energy-efficient and self-sustaining water harvesting technologies. [ABSTRACT FROM AUTHOR]

[Display omitted] • Using the crystal structure prediction approach seven new carbon allotropes are proposed. • All the hardness of these seven novel carbon allotropes exceed 50 GPa and five are superhard materials. • They are five semiconductor materials has wide band gap and two are quasi-direct band gap semiconductor materials. Carbon materials are important semiconductor materials. For enriching the structure of carbon materials, the eight novel carbons with R -3 m phase are predicted by using Random methods based on Group and Graph theories. Among these allotropes, one (R -3 m/C−8(-|-)) was excluded through stability criterion, and the others new carbon structures meet all stability conditions, including thermal stability, dynamical stability, mechanical stability, and thermodynamic stability. According to two empirical hardness model criteria, all the hardness of seven novel carbon allotropes are above 50 GPa. Particularly, R -3 m/C , R -3 m/C−2(-|-) , R -3 m/C−3(-|-) , R -3 m/C−6(-|-) , and/R−3(- |-) m/C−7(-|-) belong to superhard materials. Electronic band structures of these materials are demonstrated by HSE06 hybrid functional, where R -3 m/C , R -3 m/C−2(-|-) , R -3 m/C−3(-|-) , R -3 m/C−4(-|-) , R -3 m/C−6(-|-) , and/R−3(- |-) m/C−7(-|-) are wide band gap semiconductors, while R -3 m/C , R -3 m/C−2(-|-) are quasi-direct band gap structures. The R -3 m/C−4(-|-) exhibits the greatest elastic anisotropy in elastic modulus. There materials with different crystalline phase structures are characterized by using X-ray diffraction spectroscopy. Here, the predicted new allotropes with excellent physical properties provide theoretical guidance for further development and expansion of carbon material applications. [ABSTRACT FROM AUTHOR]

• Four new tetragonal superhard carbon allotropes were uncovered. • The four carbon allotropes are wide direct band semiconductors. • The hardness values of the four structures were 81, 72, 71, and 58 GPa, respectively. In this study, four new tetragonal sp 3 carbon allotropes with high dynamic and mechanical stabilities (I 4 1 / acd -C112, I 4/ mcm -C128, I 4/ mcm -C112, and I 4 1 / amd -C64) were predicted using first-principles calculations. The I 4 1 / acd -C112, I 4/ mcm -C128, I 4/ mcm -C112, and I 4 1 / amd -C64 allotropes exhibited semiconductor behavior, as confirmed by their wide band gaps (calculated to be 3.80, 3.22, 3.56, and 3.51 eV, respectively) and superhardness, as evidenced through hardness and ideal strength calculations. [ABSTRACT FROM AUTHOR]

Graphdiyne (GDY), an emerging type of carbon allotropes with unique sp−sp2 carbon atoms, is firstly explored for high selectivity direct electrochemical sensing of ultra‐trace level copper ions (Cu2+). It achieves a wide detection range of 0.25–380 μM and a trace level as low as 8 nM, among the best performance of reported carbon‐based sensors. It is found that GDY with unique C≡C possesses both chelating and reducing abilities to efficiently anchor and reduce Cu2+ to Cu+, eventually leading to ultrasensitive detection. [ABSTRACT FROM AUTHOR]

In this Comment, the content of the book by B.I. Kharisov, O.V. Kharissova, Carbon Allotropes: Metal-Complex Chemistry, Properties and Applications, published in 2019 by Springer Nature Publishing, has been characterized in detail. A great amount of information presented in this book is devoted to numerous varieties (allotropic modifications) of elemental carbon, each of which currently has not only purely academic, but also significant practical interest. This book is important for researchers working in the field of inorganic chemistry of carbon, as well as researchers in the field of chemistry of coordination compounds, which has traditionally been classified as inorganic chemistry since its inception. [ABSTRACT FROM AUTHOR]

Abstract Graphdiyne (GDY), an emerging type of carbon allotropes with unique sp−sp2 carbon atoms, is firstly explored for high selectivity direct electrochemical sensing of ultra‐trace level copper ions (Cu2+). It achieves a wide detection range of 0.25–380 μM and a trace level as low as 8 nM, among the best performance of reported carbon‐based sensors. It is found that GDY with unique C≡C possesses both chelating and reducing abilities to efficiently anchor and reduce Cu2+ to Cu+, eventually leading to ultrasensitive detection.

This study investigates the inclusion of different forms of carbon in CoCuMnOx solar selective coating via the low-energy consumption method “sol-gel technique”. The usage of carbon as an additive in CoCuMnOx was an attempt to enhance the spectral selectivity. Four allotropes of carbon (graphene nanoplatelets (GNP), carbon nanotubes (CNT), graphite, and charcoal) were embedded in the selective coating with different concentrations and then were deposited on smooth and roughened stainless-steel sheets. In an additional attempt to improve CoCuMnOx selectivity, three different coatings (silica, charcoal@silica, and CNT@silica) were individually applied on top of it. Each carbon allotrope showed distinct structural and optical properties of the coating. Using charcoal as an additive achieved a solar absorptance of 0.964 and a thermal emittance of 0.095, thus providing superior optical properties compared to the other allotropes. The characteristics of the coatings were detected by X-ray diffraction, Energy Dispersive X-Ray analysis, and Scanning Electron Microscope.

A metallic, covalently bonded carbon allotrope is predicted via first principles calculations. It is composed of an sp3 carbon framework that acts as a diamond anvil cell by constraining the distance between parallel cis‐polyacetylene chains. The distance between these sp2 carbon atoms renders the phase metallic, and yields two well‐nested nearly parallel bands that cross the Fermi level. Calculations show this phase is a conventional superconductor, with the motions of the sp2 carbons being key contributors to the electron–phonon coupling. The sp3 carbon atoms impart superior mechanical properties, with a predicted Vickers hardness of 48 GPa. This phase, metastable at ambient conditions, could be made by on‐surface polymerization of graphene nanoribbons, followed by pressurization of the resulting 2D sheets. A family of multifunctional materials with tunable superconducting and mechanical properties could be derived from this phase by varying the sp2 versus sp3 carbon content, and by doping. [ABSTRACT FROM AUTHOR]

Carbon dots (CDs) represent a relatively new type of carbon allotrope with a 0-D structure and with nanoparticle sizes < 10 nm. A large number of research articles have been published on the synthesis, characteristics, mechanisms and applications of this carbon allotrope. Many of these articles have also shown that CDs can be synthesized from "bottom-up" and "top-down" methods. The "top-down" methods are dominated by the breaking down of large carbon structures such as fullerene, graphene, carbon black and carbon nanotubes into the CDs. What is less known is that CDs also have the potential to be used as carbon substrates for the synthesis of larger carbon structures such as 1-D carbon nanotubes, 2-D or 3-D graphene-based nanosheets and 3-D porous carbon frameworks. Herein, we present a review of the synthesis strategies used to convert the 0-D carbons into these higher-dimensional carbons. The methods involve the use of catalysts or thermal procedures to generate the larger structures. The surface functional groups on the CDs, typically containing nitrogen and oxygen, appear to be important in the process of creating the larger carbon structures that typically are formed via the generation of covalent bonds. The CD building blocks can also 'aggregate' to form so called supra-CDs. The mechanism for the formation of the structures made from CDs, the physical properties of the CDs and their applications (for example in energy devices and as reagents for use in medicinal fields) will also be discussed. We hope that this review will serve to provide valuable insights into this area of CD research and a novel viewpoint on the exploration of CDs. [ABSTRACT FROM AUTHOR]

Although isolated nonhexagonal carbon rings in graphene are associated with strain relaxation and curvature, dense and ordered arrangements of four‐, five‐, and eight‐membered rings with strained carbon–carbon bonds can tile 2D planar layers. Using the Boltzmann transport equation formalism in combination with density functional theory calculations, how the presence of nonhexagonal rings impacts the thermal conductivity of three 2D carbon allotropes: T‐graphene (four and eight rings), biphenylene (four, six, and eight rings), and net‐graphene (four, six, and eight rings), is investigated. The phonon thermal conductivity (κph), which captures three‐phonon, four‐phonon, and phonon–electron interactions, is significantly lowered with respect to pristine graphene. In compensation, the electron thermal conductivity (κe), which captures electron–phonon interactions, is enhanced to record high values, such that the room‐temperature total thermal conductivity κtotal = κph + κe approaches the values of pristine graphene. 2D carbon allotropes could be of interest for applications requiring thermal energy transfer by a combination of diffusion of electrons and phonon vibrations. [ABSTRACT FROM AUTHOR]