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Coal as a carbon source for carbon nanotube synthesis
... There are three techniques that have been developed to produce CNTs: discharge, laser ablation, and chemical vapor deposition (CVD) (See & Harris, 2007;Purohit et al., 2014;Taylor et al., 2021). The basic elements for the formation of carbon nanotubes are: catalysts, a source of carbon, and enough energy (Moothi et al., 2012). Catalysts play a key role in the CVD synthesis of CNTs and therefore improving the desired characteristics of catalyst will improve the obtained CNTs quality as well as the process yield (Saifuddin et al., 2013;Chen et al., 2021;Saleh, 2021). ...
... Carbon nanostructures are commonly synthesized using transition metal nanoparticles as catalysts, such as Fe, Ni, Co, and Mo (Thess et al., 1996). Fossilbased hydrocarbon and plant-based hydrocarbon are the main carbon sources for the synthesis of CNTs (Moothi et al., 2012;Shah & Tali, 2016). The energy source may be electricity from an arc discharge, heat from a furnace (~900°C) for CVD, or the high-intensity light from a laser ablation (Guray, 2016). ...
This may be attributed to the facts that nanotechnology has shown an excellent ability to control the release pattern of active ingredients of pesticides, so that it can achieve long-term functions more effectively, thus overcoming the problems of agricultural runoff and residual pesticide accumulation. In addition, Nanopesticides have shown greater solubility and stability of active ingredients, which can effectively control pests (Akhtar et al.,2020). In this study, the insecticidal relative toxicity of carbon nanotubes (CNTs) synthesized from seeds of Iraqi date palm Phoenix dactylifera L. using a chemical vapor deposition (CVD) method was investigated. These Nanoparticles were evaluated against adult and larvae of the Khapra beetle, Trogoderma granarium. The results indicated that CNTs (25, 50 and 100 ppm) caused mortality of the Khapra beetle under laboratory conditions. Additionally, the germination percentage of wheat, Triticum aestivum L. grains, has not been affected by the carbon nanotube treatments at 25-100 ppm. This study demonstrates the potential of CNTs as a technology for population control of T. granarium because of their toxicity to larvae and adults.
... According to Williams et al. [99], coal as an electrode material would reduce raw material costs tenfold. Anthracite has been employed in the arc discharge method with copper catalysis to produce branching CNTs (BCNTs) with a purity of approximately 70% [100,101]. Because only a tiny number of BCNTs were created in tests using high-purity graphite powder as the carbon source rather than coal powder, it is assumed that coal plays a substantial role in this process. ...
Growing energy consumption and worries about climate change and greenhouse gas emissions have motivated a quest for sustainable and renewable energy sources. Because it is renewable, carbon-neutral, and ecologically beneficial, bioenergy has emerged as an appealing alternative to traditional fossil fuels. Microstructural maneuvering is a promising strategy for increasing the efficiency and efficacy of bioenergy production from carbon-based products and biomasses. Carbon-based products in bioenergy production offer various benefits over traditional fossil fuels. They are renewable and sustainable energy sources that can minimize our reliance on finite and dwindling fossil fuels. Second, they have a reduced carbon footprint and release fewer greenhouse emissions, which can aid in climate change mitigation. They can increase energy availability and security, particularly in rural and distant locations with limited access to traditional energy infrastructure. Further, crops, industrial waste, and municipal garbage are all plentiful and diverse sources of biomass that may be utilized to produce bioenergy. Microstructural maneuvering may be employed to optimize the conversion of various biomasses into energy by manipulating their physical and chemical characteristics. Pre-treatment procedures can improve biomass accessibility and reactivity by breaking down complicated structures and eliminating contaminants. Enzymatic and microbial conversion may also be optimized by choosing suitable enzymes and microorganisms in controlling features like specificity, stability, and activity. Therefore, this chapter explores various possibilities for generating bioenergy from carbon-based precursors and biomasses.
... The exploration of synthesizing soft and environmentally friendly carbon materials, such as nanocarbon derived from coal and coke, stands as a promising research avenue. This is attributed to its potential to yield high-quality materials at a low cost, along with advantages like environmental friendliness, mild processing conditions, and scalability [12][13][14][15]. ...
The choice of precursor and simple synthesis techniques have decisive roles in the viable production and commercialization of carbon products. The intense demand for developing high-purity carbon nanomaterials through inexpensive techniques has promoted the usage of fossil derivatives as a feasible source of carbon. In this study, Vietnamese-coal-derived porous carbon (PC) was used to fabricate coal-derived porous carbon nanomaterials (CDPCs) using the modified Hummers method. The resulting porous carbon nanomaterials achieved a nanoscale structure with an average pore size ranging from 3 to 10 nm. The findings indicate that CDPC exhibits well-developed micropores and mesopores. The presence of macropores and mesopores not only facilitates the complete immersion of the material in the electrolyte but also effectively shortens the ion diffusion pathways. CDPC boasts a high carbon content, constituting 80.88% by weight. Electrochemical impedance spectroscopy (EIS) Nyquist plot of electrodes made from CDPC showed good conductivity value with low charge-transfer resistance. This electrode worked well and stably with capacitance retention of 74.7% after 1000 cycles. The CDPC specific capacitance reached 236 F/g under a current density of 0.1 A using the constant current discharge method and then decreased as the current density increased. Based on the results of the electrochemical properties of the materials, the energy storage capacity of the CDPC material was good and stable. This investigation presents an eco-friendly methodology for the judicious utilization of coal in energy storage applications, specifically as electrodes for supercapacitors and anodes for Li-ion batteries.
... The perception of coal as a traditional industry has shifted, expanding its applications into non-conventional domains such as activated carbon [10][11][12] and activated carbon fibers [13,14]. Recent advancements have diversified coal's applications, transforming it into a valuable carbon-rich precursor for various nanomaterials, including graphene quantum dots (GQDs), graphene oxide, nanodiamonds, carbon nanotubes (CNTs), and more [15][16][17][18][19][20][21]. Zhang et al. [16] enhanced Li + conductivity and storage capacity by producing GQDs using high-crystallinity Taixi anthracite power with excellent thermal stability. ...
Anthracite stands as a valuable precursor for carbon materials, owing to its high carbon content. However, producing activated carbon from anthracite presents significant challenges due to its elevated ash content (23–40 wt%) and crystalline nature. The high ash content not only fails to contribute to the activation process but also obstructs pore formation on the carbon surface. To address these challenges, this study explores the preparation of activated carbon from anthracite using KOH activation. This method demonstrates remarkable efficacy in enhancing reactivity beyond the inherent physical properties of anthracite. In contrast to physical activation, the utilization of KOH as a chemical agent substantially enhances the specific surface area, resulting in a production yield of 62% and a specific surface area that reaches up to 1596 m2/g at a KOH/anthracite weight ratio of 4.0. Moreover, rinsing the activated sample with tap water achieves an ash removal rate of about 37.9%, surpassing twice the rate achieved through acid pretreatment (67.0%). A noteworthy observation from this study is the substantial reduction in the content of major ash components, such as silicon (Si) and aluminum (Al), both of which are prominent constituents in anthracite ash. Following KOH activation, their levels decrease by approximately 54% to 65%, respectively. These findings highlight the potential of utilizing available anthracite, even with elevated ash content, as a superior carbon material. Fundamentally, the KOH activation method serves a dual purpose: it effectively reduces ash content and promotes pore creation within a highly alkaline environment. This dual advantage positions the method as a promising approach for the production of top-tier activated carbon.
... The continuously increased commercial uses of engineered carbon-based nanomaterials include technical, medical, environmental, and agricultural applications (Zaytseva & Neumann, 2016). Coal can be an abundant and cheap natural precursor utilized for the synthesis of carbon-based nanomaterials (Moothi et al., 2012), which can be applied in the energy and environmental sectors. ...
Coal is a vital carbon-based raw material which is used in the production of various advanced nanomaterials. This particularly holds true for the relevant research and development trends in India. New more environmentally friendly processes are under development with respect to metallurgical coke making and quality enhancement of high-ash Indian coal. Compared with chemical and physical methods, beneficiation of high-ash coal and its combustion by-products with organic liquids (various natural oils) are much more superior in terms of costs, efficiency, and environmental implications. Nanodiamonds have emerged as a key platform for nanoscience and nanotechnology developments. Indian scientists have applied eco-friendly and cost-effective ultrasonic assisted wet-chemical method to low-quality NE Indian coal and the resulting nanodiamond particles could have a wide range of applications in the field of microelectronics, optoelectronics, and biosensing. Also, Indian scientists have been working on ultrasonic-assisted chemical synthesis of activated carbon from low-quality subbituminous coal and its preliminary evaluation towards supercapacitor applications. This article shows that coal is a versatile and valuable raw material which should be saved for future generations at all costs.
... From an environmental standpoint, the application of byproducts and wastes has been largely explored to produce new carbonaceous products [26][27][28][29][30][31][32][33][34][35]. Therefore, coal tar pitch (CTP), a byproduct of the coal tar distillation process, is an abundant source for the production of syngas and carbon nanomaterial due to its polycyclic aromatic hydrocarbons (PAH) composition [36,37]. ...
Thermal plasma-assisted processing is an effective process for the synthesis of gas (CO and H 2) and carbonaceous materials production from industrial waste. In this paper, a DC plasma torch designed with two vortices chambers has been developed, and its characteristics have been experimentally tested. The plasma torch operates with different plasma working gases, including steam. The results of coal tar pitch (CTP) processing will be presented as a possible ecological application. CTP is a waste from the steel industry mainly composed of polycyclic aromatic hydrocarbons. The experimental results will be discussed with thermodynamic calculations and numerical simulation of the heat and mass transfer in the DC plasma torch and the chemical reaction chamber. The simulations were carried out to clarify the regions of gas flow and temperatures for producing synthesis gas and carbon nanomaterial. The results enable one to predict the produced gas composition and carbon nanomaterial properties. The physicochemical properties of carbon nanomaterial and synthesis gas show high efficiency in converting CTP into high-value-added products.
... At present, carbon materials prepared by pyrolysis are usually directly converted from solid raw materials to solid residues. For example, Carbon nanotubes were synthesized from coal by Moothi et al. [15]. Wang et al. [16] prepared the three-dimensional laminated porous carbon materials from kiwi fruit. ...
The heavy bio-oil produced from biomass pyrolysis was used as carbon source to prepare porous biochar by one-step template method for methylene blue adsorption in wastewater. The effects of different templates and mass ratios on characteristic of porous biochar were studied. The methylene blue adsorption characteristics of porous biochar were investigated, and that of activated carbon was also discussed for comparison. The result showed calcium citrate was the most suitable template agent with the highest yield and the best microstructure of biochar. The specific surface area and micropore volume first increased and then decreased with the increasing mass ratio of template to bio-oil and carbonization temperature, reaching the maximum value of 922 m²/g and 0.182 cm³/g at 800 °C when the mass ratio was 2:1. The methylene blue adsorption capacity increased along with the increase of specific surface area and pH value. The adsorption capacity of porous biochar reached the maximum value of 411 mg/g at pH of 12, which was 28% higher than that of activated carbon. The adsorption process was consistent with Langmuir isothermal adsorption model and pseudo second-order kinetic model. This paper provides a new method to prepare effective adsorbent from heavy bio-oil for methylene blue removal.
... As well known, carbonization is usually carried out by thermal treatment under a vacuum or inert atmosphere at high temperatures of 600-900 • C to get rid of the non-carbon elements of hydrogen, oxygen, and nitrogen [13]. Carbon can be derived from a variety of precursors, such as the natural sources like coal, petroleum pitch, wood, and coconut husk for commercial activated carbon [14][15][16][17], a massive number of biomass precursors developed from plants and animals for the biomass char, the organic chemicals and polymers for diverse carbon nanomaterials [18]. Another thermochemical carbonization route is hydrothermal conversion of saccharides or biomass into hydro char in an aqueous medium, which is accomplished in a pressure vessel in a low temperature range of 160-300 • C less than 24 h [19]. ...
The conventional synthesis of porous carbon materials is primarily relied on the activation and template process. This work successfully develops a one-step method for preparing amorphous porous carbon nanoparticles (APCNs) with a high specific surface area (SSA) in organic solvents under ambient atmosphere. The APCNs are formed mainly by the reaction of ferrocene with ammonium chloride at only 180 °C for 1 h in different solvents. Several ferrocene derivatives and KOH activation are also utilized to improve the textural properties of the APCNs. It is found that the high solubility of (C5H5)2Fe and FeCl3·6H2O in a solvent is the most essential factor associated with the decrease of carbon nanoparticle size. The smaller the nanoparticle size, the larger the SSA of APCNs. The APCNs prepared in phenoxyethanol have a median size of 32.74 nm, exhibiting an SSA of 689 m²/g. The high solubility of NH4Cl can also contribute to reducing the nanoparticle size. The binary solvent consisting of phenoxyethanol and glycol has an excellent solubility for (C5H5)2Fe, FeCl3·6H2O, and NH4Cl, in which the prepared APCNs have a median size 11.48 nm and a higher SSA of 936 m²/g. Besides, the benzoyl substituted group on the cyclopentadiene can facilitate formation of small mesopores. The oxygen and nitrogen are in situ doped in the APCNs. Activation is also effective, and the SSA of APCNs reaches a maximum value of 1575 m²/g at a KOH ratio of 2:1. The solvent-based synthesis is unique and competitive in terms of high efficiency and energy conservation.
... The high cost of CNTs and CNTs products impedes the exploration of other enormous potential applications which place cumulative demand on ways to reduce CNTs' production costs and of course augment its affordability. In achieving this, other carbonaceous sources have been widely investigated such as coal [7], palm kernel shell [8], waste tires [9], waste plastics [10][11][12][13][14][15], etc. The extensive the use of air, steam or CO 2 to facilitate the devolatilization and formation of pure carbon in the biochar [24,25]. ...
The future and continuity of nanomaterials are heavily dependent on their availability and affordability. This could be achieved when cheap materials are actively employed as starting materials for nanomaterials synthesis. In this study, waste corn cob char was used as support during the preparation of the NiMo catalyst, and the effect of different char-activating techniques on the microstructure, yield and quality of carbon nanotubes (CNTs) obtained from waste polypropylene (PP) plastics using the chemical vapor deposition (CVD) technique was investigated. Properties of the catalysts and obtained nanomaterials were evaluated by XRD, SEM, N2 physisorption experiment, FTIR, Raman spectroscopy and TEM. Results showed improved surface properties of the NiMo catalyst supported on chemically (NiMo/ACX) and physically activated char (NiMo/ACT) compared to the NiMo catalyst supported on non-activated char (NiMo/AC0). High-quality CNTs were deposited over NiMo/ACT compared to NiMo/ACX and NiMo/AC0. It was also observed that different activation methods resulted in the formation of CNTs of different microstructures and yield. Optimum yield (470.0 mg CNTs/g catalyst) was obtained with NiMo/AC0, while NiMo/ACT gave the least product yield (70.0 mg CNTs/g catalyst) of the as-produced nanomaterials. Based on the results of the analysis, it was concluded that utilizing a cheap pyrogenic product of waste corn cob as a catalyst support in a bimetallic NiMo catalyst could offer a promising approach to mass producing CNTs and as a low-cost alternative in CNTs production from waste plastics.
... In the past 30 years, researchers have developed several methods to synthesize CNTs from coal and coal-based derivatives, e.g., the arc discharge, laser ablation, chemical vapor deposition (CVD), etc. As a cheap carbon source, coal has shown a potential for mass production of CNTs [60]. ...
Coal is one of the natural materials with three-dimensional (3D) cross-linked network structure composed of aromatic units and hydroaromatic groups. The unique molecular properties of coal and its derivatives endow them with great potential as resources to synthesize functional carbon materials. Up to date, much progress has been made in coal-based functional carbon materials in the past two decades, which need to be comprehensively summarized with an aim of streamlining and clarifying the future directions in the fabrication of functional carbon materials from coal and its derivatives. Here, the recent progresses in the synthesis of coal-based carbon materials (CCMs), including porous carbons, fullerenes, carbon nanotubes, carbon spheres, carbon fibers, graphene and carbon dots are summarized. The modification strategies of CCMs are also summarized, which are crucial to tune the structure and properties of the CCMs in terms of their applications. Finally, the perspectives and the future developments of CCMs are discussed. This comprehensive review may shed a new light on the design and production of coal-based functional carbon materials for applications in energy storage, catalysis, composites materials, and environment protection.
... Although this review discussed the preparation of coal-based CNTs in various aspects, this endeavor remains challengings. As such, its industrial production is not yet possible [102,103]. Some of the current challenges and future directions in coal-based CNT preparation via catalytic pyrolysis must be comprehensively investigated from the following aspects. ...
In view of the Chinese government's “30–60 target” for “carbon peak, carbon neutral” coal utilization, the persistent bottleneck problems in coal consumption of low utilization efficiency, serious environmental pollution, and high carbon emissions have once again become critical issues. The preparation of advanced carbon materials with coal as the precursor can realize the clean, efficient, and low-carbon utilization of coal resources. Coal is a natural low-cost carbon source with a rich aromatic structure that can be used for the preparation of carbon nanomaterials with excellent physical and chemical properties via arc discharge, laser ablation, chemical vapor deposition, and catalytic pyrolysis. In this study, coal-based carbon nanotubes (CNTs) were investigated. First, progress in research on CNTs prepared by conventional, microwave, and plasma-catalyzed pyrolysis methods were discussed in depth. Second, the effects of metal catalysts, including alkali metals, transition metals, and other metals, on the preparation of CNTs were analyzed. Third, the formation mechanisms of the catalytic pyrolysis of CNTs, namely, “Tip growth” and “Base growth” models, “Step growth” model, and “Particle-Wire- Tube growth” model, were summarized. Finally, the current challenges and future direction in the development for preparing coal-based CNTs were explored.
... Obtained activated carbons fi x and retain on their surface organic and inorganic substances they contact. They are composed of a carbon skeleton with very fi ne pores and channels of varying depths and diameters; on these surfaces takes place the concentration of adsorbed substances [1]. ...
This paper presents the results of scientific research aimed at studying processes of obtaining activated carbon from wood charcoal. We presented methods for determining the structure parameters and specific surface of carbonic adsorbents. Scientific research results allow concluding that wood charcoal is a cheap and effective material for the synthesis of activated charcoal.
... The high purity carbon product is then sold as an oil fuel additive for marine or other markets (Snaith and Unsworth 2017). In another example, ultrafine pure carbon is commonly used for the synthesis and production of various carbon nanotubes and nanomaterials (Moothi et al. 2012;Qiu et al. 2004Qiu et al. , 2002. Lastly, Huang et al. (2018) has shown that ultrafine grinding can release rare earth minerals from coal refuse permitting subsequent concentration and recovery. ...
In this study, the energy efficiency of three alternative grinding media including, coarse silica beads, fine silica beads, and granular sand, were evaluated and compared against standard stainless steel. Stirred mill test results show that both silica beads and granular sand were more efficient than stainless steel in producing ultrafine particles following the order of coarse silica beads>granular sand>fine silica beads>stainless steel. The finest product size corresponding to a P80 value of 2.33 μm was generated by coarse silica beads with a nominal size of 420 × 1190 μm, which also consumed the least amount of grinding energy. The specific energy input was reduced by almost 50% as opposed to that of stainless steel, while the operating work index was reduced by 87%. Overall, the test data indicate that grinding media density, media particle size and shape all play a role in determining the optimized grinding behavior of the coal material.
... Keywords: coal, pilot-industrial installation, adsorbent, carbonization, activation, purification Recent decades have been marked by a surge of scientific activity in the development and study of carbon materials (CM). This is reflected in the targeted synthesis of allotropic forms of carbon (carbohydrates, fullerenes, nanotubes, compasses, etc.), as well as in the creation of a wide range of porous materials in a series of mixed (transitional) forms of carbon, which are of practical interest as adsorbents, catalysts, and carriers for catalysts, substrates in new generation current sources (lithium-ion batteries, supercapacitors, ionistors and fuel cells), etc. [1][2][3][4]. ...
... Recent decades have been marked by a surge of scientific activity in the development and study of carbon materials (CM). This is reflected in the targeted synthesis of allotropic forms of carbon (carbohydrates, fullerenes, nanotubes, compasses, etc.), as well as in the creation of a wide range of porous materials in a series of mixed (transitional) forms of carbon, which are of practical interest as adsorbents, catalysts, and carriers for catalysts, substrates in new generation current sources (lithium-ion batteries, supercapacitors, ionistors and fuel cells) etc. [1][2][3][4][5][6][7]. ...
... A range of different carbon sources for the production of CNTs has been investigated, including methane [87,88], coal [89] and aromatic hydrocarbons including benzene, toluene and xylene [90][91][92] and biomass such as coconut oil [93] and animal fat [94]. Typical catalysts include the use of nano-particle sized transition metals such as nickel, iron and cobalt and organo-metallic catalysts such as ferrocene [86,90,95,96]. ...
More than 27 million tonnes of waste plastics are generated in Europe each year representing a considerable potential resource. There has been extensive research into the production of liquid fuels and aromatic chemicals from pyrolysis-catalysis of waste plastics. However, there is less work on the production of hydrogen from waste plastics via pyrolysis coupled with catalytic steam reforming. In this paper, the different reactor designs used for hydrogen production from waste plastics are considered and the influence of different catalysts and process parameters on the yield of hydrogen from different types of waste plastics are reviewed. Waste plastics have also been investigated as a source of hydrocarbons for the generation of carbon nanotubes via the chemical vapour deposition route. The influences on the yield and quality of carbon nanotubes derived from waste plastics are reviewed in relation to the reactor designs used for production, catalyst type used for carbon nanotube growth and the influence of operational parameters.
Graphic Abstract
... On the one hand, the cross-linked structure of coal was destroyed, and the bridge bonds were first broken to generate free radical "fragments". Subsequently, aliphatic side chains, oxygen-containing functional groups and low-molecular compounds in the coal were cracked to produce gaseous hydrocarbons (CH 4 , C 2 H 4 and C 2 H 2 , etc.), carbon oxides (CO and CO 2 ), hydrogen, water and other primary pyrolysis products [53][54][55]. With the increase of pyrolysis temperature, the primary pyrolysis products were further cleaved into secondary pyrolysis products. ...
Carbon nanotubes (CNTs) and activated carbon (AC) hybrids were obtained by co-pyrolysis of potassium hydroxide and bituminous coal. Scanning electron microscopy (SEM), thermogravimetric analysis (TGA), Raman spectroscopy, X-ray Diffraction (XRD), and nitrogen adsorption measurements were used to investigate the characteristics of the samples and the effects of the final pyrolysis temperature and time on the structure of the carbon materials. The results indicated that the optimal range for the pyrolysis temperature and time for CNT growth were 900–950 °C and 45–90 min, respectively. The diameters of the as-prepared CNTs were in the range of 50–250 nm and their lengths were ∼15 μm. During the pyrolysis process, potassium hydroxide not only acted as the catalytic precursor to catalyze the CNT growth but also reacted with carbon to produce abundant micropores. Furthermore, the content of CNTs in the product after demineralization was significantly reduced. It was further confirmed by Inductively Coupled Plasma (ICP) analysis that the content of Fe, Co, and Ni decreased after demineralization, indicating that minerals in coal play an important role in the growth of coal-based CNTs.
... Therefore, exploring different usages of coal by upgrading it to high value-added products such as graphitic materials and composites is not only economically attractive but environmentally favored. Although naturally occurring coal has been widely converted into liquid [1], gaseous [2] fuels via liquefaction and gasification, respectively, its application as the precursors for synthetic carbonaceous materials such as carbon quantum dots, carbon nanotubes, carbon nanofiber and graphenedwidely used in fields ranging from electronics to energy storage [3e8]dis just recently emerging via methods such as wet-chemistry [9,10], supercritical fluid [11], and high-temperature furnace annealing [12]. However, these methods require multiple steps or harsh reaction conditions, which generate chemical wastes or require high energy input. ...
Despite much progress, developing a cost-effective and environmental-friendly method to upgrade earth-abundant coal into high value-added products is still a grand challenge. Here, we report a one-step and facile approach to synthesize graphene based materials from coal under ambient conditions via direct CO2 laser scribing. The obtained laser scribed graphene from coal (C-LSG) has been well characterized, showing good electrical conductivity (12 Ω/square), high electrochemical sensitivity and ionic storage properties. These properties make C-LSG a multifunctional material for applications in Joule heating, electrochemical dopamine sensing, and supercapacitors. Moreover, when electrochemically deposited with FeNi hydroxide, the hybridized FeNi/C-LSG shows impressive electrocatalysis performance toward oxygen evolution reaction. As such, this direct laser scribing of coal into graphene based materials can not only potentially expands new business opportunities by adding coal into the value-chain of industries that usually do not use coal as the starting materials in their manufacturing processes but also brings down the cost of the graphene based materials, which would make their deployment in various field more economically attractive.
... The means of arcing method enable production of singlewall carbon nanotubes, multiwall carbon nanotubes (Moothi et al., 2012), double-walled carbon nanotubes (Qiu et al., 2007) branched carbon nanotubes , bamboolike nanotubes (Li et al., 2002) and graphene (Awasthi et al., 2015). Williams et al. (1999) reported on obtaining single-wall nanotubes from coal via Ni-Y catalyst in arc synthesis. ...
The current book aims at demonstrating how the various types of carbonaceous materials could possibly be applied for nanomaterials synthesis and at utilizing the data of practical
experience of anthropogenic carbon nanoparticles preparation from the coal carbonization products and their further use. As nanomaterials largely influence the environment, our book contributes to the discussions of this impact both on the
environment and on the human in terms of ethics, society and ecology. The feasibility to produce nanomaterial from biomass and the products of its pyrolysis is a topic which is worth to be studied and is an outlined problem in this book.
The target audience for this book includes students, post-graduates in engineering,
scientists and professional engineers who are interested in nanomaterials production from carbon-derived sources.
... There are three general methods for the synthesis of CNTs, namely (i) arc discharge; (ii) laser ablation; (iii) and chemical vapor deposition (CVD), among which the latter process offers the most promising prospect for largescale production with low cost [29]. Multi-walled carbon nanotubes (MWNTs, CNTs > 98% carbon basis) prepared by chemical vapor deposition (CVD) using cobalt and molybdenum as catalysts (CoMoCAT) were purchased from Sigma-Aldrich. ...
This work investigates the role of carbon nanotube (CNT) tribolayer formation in reducing friction and adhesion of an Al-alloy engine block material (Al-6.5% Si, 319 Al) sliding against a common piston ring coating, namely, CrN coated steel, when tested under a boundary lubricated condition. Coefficient of friction (COF) values were determined using pin-on-disk type tests as a function of sliding distance using CNT added to ethanol and ethanol without CNT addition. Boundary lubricated tests that used ethanol with 0.14 wt.% CNT resulted in a steady-state COF of 0.16, and reduced Al adhesion to the CrN due to the formation of CNT tribolayers on the Al-alloy contact surfaces. Raman spectroscopy and high resolution SEM suggested the CNT fibers in the tribolayers were damaged and possibly subjected to plastic deformation, and the carbon bonds were possibly passivated by the -H and -OH dissociated from ethanol as suggested by FTIR. The low friction and adhesion observed when ethanol with 0.14 wt.% CNT was used was attributed to the sliding-induced bending and curling of the CNT tribolayers, leading to the formation of rolled sections of tribolayer with a cylindrical morphology (diameter of ~ 1 µm) that reduced direct contact between Al-alloy and CrN surfaces.
Coal exploration is a very demanding task, highly dependent on geological and economic factors and the utilization of coal. This lecture text includes information on a variety of geological techniques used in the exploration of coal and coal-bearing sequences, as well as on the calculation, assessment, classification, and reporting of coal resources and reserves. The main features of coal utilization and some environmental aspects are explained briefly. Special attention is paid to the by-products of coal utilization, their uses, and possible role in a zero-waste strategy.
Graphical abstract
Seaweed biomass of Gracilaria edulis was effectively converted into biocarbon materials at 800°C for 1 hour under nitrogen gas flow atmosphere. The effect of HCl acid washing and ZnCl2‐assisted chemical activation process on the physicochemical and capacitive performances was investigated and the obtained results were compared with their pristine counterpart. The formation of N, O, and S self‐doped biocarbon materials from G. edulis biomass was confirmed by carbon, hydrogen, nitrogen, and sulfur (CHNS), scanning electron microscopy‐energy dispersive X‐ray (SEM‐EDX) and X‐ray photoelectron spectroscopic (XPS) analyses. Further, the specific surface area of acid‐washed and activated biocarbon materials were respectively found to be 1100 and 774 m² g⁻¹, which are much greater than their pristine counterpart (111 m² g⁻¹). The obtained pristine (GE‐PC), acid‐washed (GE‐AWC), and activated (GE‐AC) biocarbon materials were effectively explored as the electrode material for symmetric supercapacitor and showed the specific capacitance value of 33.9 (GE‐PC), 58.3 (GE‐AWC) and 76.5 (GE‐AC) F g⁻¹ at 1 A g⁻¹ using 1 M KOH electrolyte.
The massive conversion of resourceful biomass to carbon nanomaterials not only opens a new avenue to effective and economical disposal of biomass, but provides a possibility to produce highly valued functionalized carbon-based electrodes for energy storage and conversion systems. In this work, biomass is applied to a facile and scalable one-step pyrolysis method to prepare three-dimensional (3D) carbon nanotubes/mesoporous carbon architecture, which uses transition metal inorganic salts and melamine as initial precursors. The role of each employed component is investigated, and the electrochemical performance of the attained product is explored. Each component and precise regulation of their dosage is proven to be the key to successful conversion of biomass to the desired carbon nanomaterials. Owing to the unique 3D architecture and integration of individual merits of carbon nanotubes and mesoporous carbon, the as-synthesized carbon nanotubes/mesoporous carbon hybrid exhibits versatile application toward lithium-ion batteries and Zn-air batteries. Apparently, a significant guidance on effective conversion of biomass to functionalized carbon nanomaterials can be shown by this work.
Electrochemical hydrogen storage, which can be performed at ambient temperatures and mild pressures, is regarded as a promising technique to store hydrogen safely and efficiently. In this study, the electrochemical hydrogen storage performance of activated carbon was improved by synthesizing a graphitized microcrystalline porous carbon material through a facile one-step catalytic carbonization activation procedure using coal as the raw material. Owing to the synthetic effect of the conductive network and the hierarchical porous structure, the carbon electrode exhibited high capacity, excellent rate performance, and substantial cycling stability for electrochemical hydrogen storage. The hydrogen storage capacity of the material was 278 mA h g−1 at a current density of 100 mA g−1, with considerable capacity retention of 86% after 50 cycles. The electrode exhibited superior rate capacity of 260 mA h g−1 at 200 mA g−1. Porous carbon with microcrystalline graphite was demonstrated to be an efficient electrode for electrochemical hydrogen storage.
Biomass is considered a promising carbon containing solid renewable resource, which has the characteristics of environmental protection, large total amount and wide distribution. Biomass can be used to produce bioenergy and green chemicals, and also act as the raw material for advanced carbon materials. This review summarized the preparation technologies of high value-added carbon materials (HVCMs) such as activated carbon, carbon nanotubes, carbon nanofibers and graphene in recent decades, summarized the preparation methods, properties and applications of HVCMs, and made an in-depth study on the raw material selection, preparation methods, reaction conditions and formation mechanism of biomass-based high value-added carbon materials (BHVCMs). Finally, the existing problems and future work were put forward to help the large-scale preparation of BHVCMs and promote the resource utilization of biomass.
The development of advanced coal-based functional nanomaterials is of great significance for clean and effective utilization of coal resources. Herein, we report novel coal-based ultra-fine carbon nanosheets (UCNSs) prepared by chemical oxidation of bituminous coal with a high yield of 40.0 wt%. UCNSs show a lamellar size of 10–20 nm, mainly composed of 63.5 at.% carbon, 5.1 at.% nitrogen, and 31.4 at.% oxygen. The structural merits of suitable size distribution, enriched functional groups, and highly conjugated core enable the UCNSs showing a tri-functional reinforcement for carbon nanofibers prepared by electrospinning and carbonization. Thanks to the strong cross-linking effect and formation of entire conductive networks, the UCNS-embedded carbon nanofiber fabrics show 32.6 and 1.5 times improved mechanical strength and electrical conductivity, respectively, than the one without UCNSs. What's more, the exposed edges of UCNSs act as active sites for ultrafast capacitive energy storage, leading to the free-standing fabric with significantly improved capacitance and rate performance (191.2 F g⁻¹ at 1 A g⁻¹, 113.5 F g⁻¹ at 50 A g⁻¹) for aqueous supercapacitors. This work may provide a new thought for high-efficient and high-value-added utilization of coal resources.
A unique bottom-up strategy was proposed for high quality electrocatalyst composed of uniform metal alloy nanoparticles embedded in carbon matrix using low-cost coal as precursor, which was realized by coordination of coal-based carbon quantum dots and metal ions followed by annealing. The as-synthesized electrocatalyst showed impressive electrocatalytic oxygen evolution performance. This method offered a general way to synthesize high quality nano-catalyst using low-cost coal as raw material.
Heavy carbonaceous materials (HCMs) such as coal are mostly used for nonrenewable power generation, while derivatives such as tar and pitch are often discarded by-products. Upgrading HCMs for a broad array of potential applications including their use in batteries, membranes, and catalysts could play an important role in the global demand for carbon neutralization. The diversity of HCMs is a technological asset that allows for the direct synthesis of highly customizable materials suited for specific applications. Herein, we will discuss state-of-the-art engineering techniques that can be employed to upscale HCMs and how the nature of the carbon source affects the final product. Further, we illustrate how machine learning (ML) methods can empower the screening of carbonaceous sources from this large family of materials with extremely diverse chemistry. We will also discuss data-driven methods to identify and prioritize the effects of individual processing parameters that could lead to a consistent as well as flexible manufacturing process.
Many countries are currently making the transition from CAD modeling to BIM modeling and project management. There are considerable challenges for a society to integrate these new methodologies in an industry that is so changing, where many professional disciplines are involved, and whose economic contribution is relevant for the growth of a nation. There are different authors in the global context that have documented the advantages in the implementation of the methodology, but this does not mean that it is a simple process. In this sense, the undergraduate programs of universities play a fundamental role. This document describes the exercise that was done, on the recognition of the process that would be required to achieve the implementation of the BIM methodology in the current Civil Engineering program of the Catholic University of Colombia, in this, it reflects on the most relevant aspects to consider in the approach of BIM from the academy, particularly from Engineering.
The present research work deals with the synthesis and characterization of the graphene oxide (GO) and graphene from coal as a precursor material. First, the collected coal was dried and converted into the finely powder forms using ball milling process. The GO was synthesized from the coal by means of strong oxidizing agents and it was further reduced in the presence of chemical reagent (sodium borohydride) and plant origins (orange peel extract (OPE)) to produce graphene nanosheets. The Fourier transform infrared (FTIR) spectroscopy, Ultraviolet-Visible (UV-Vis) spectroscopy, dynamic light scattering (DLS) analysis, X-ray diffraction (XRD) analysis, scanning electron microscopy (SEM), simultaneous thermogravimetry (TG) method with differential thermal analysis (DTA) and differential scanning calorimetry (DSC) were studied to investigate the synthesis of graphene oxide (GO) and graphene and their nanostructure morphology, size distribution in solution along with thermal properties. The FTIR and UV-Vis spectroscopy established the formation of GO from coal, and DLS and SEM analysis further confirm the developed methodology for synthesis of the GO and graphene from coal resources. The XRD analysis established the successful synthesis of the GO from the coal. The TG method with DTA and DSC also verified the prepared GO and graphene. The methodologies implemented here for synthesis of the GO and subsequent graphene has fulfilled the objectives of the current research works.
As a natural abundant high-carbon resource, the use of coal to develop carbon nanomaterials is an important research topic. In recent years, a variety of carbon materials with different morphologies and nanotextures have been designed and constructed using coal and their derivatives as precursors, and their use in energy storage, catalysis, adsorption and absorption have been explored. State-of-the-art research on carbon nanomaterials derived from coals of different rank and their derivatives are summarized with specific attention to the synthesis strategies and structure control. The use of these coal-derived carbons for energy storage, such as secondary batteries and supercapacitors, is also discussed in terms of their structural features. The review aims to provide valuable insight into the present challenges and inspire new ideas for the development of advanced coal-derived carbon materials.
Carbon dots are zero‐dimensional carbon nanomaterials with quantum confinement effects and edge effects, which have aroused great interests in many disciplines such as energy, chemistry, materials, and environmental applications. They can be prepared by chemical oxidation, electrochemical synthesis, hydrothermal preparation, arc discharge, microwave synthesis, template method, and many other methods. However, the raw materials' high cost, the complexity and environmental‐unfriendly fabrication process limit their large‐scale production and commercialization. Herein, we review the latest developments of coal‐based carbon dots about selecting coal‐derived energy resources (bituminous coal, anthracite, lignite, coal tar, coke, etc.) the developments of synthesis processes, surface modification, and doping of carbon dots. The coal‐based carbon dots exhibit the advantages of unique fluorescence, efficient catalysis, excellent water solubility, low toxicity, inexpensive, good biocompatibility, and other advantages, which hold the potentiality for a wide range of applications such as environmental pollutants sensing, catalyst preparation, chemical analysis, energy storage, and medical imaging technology. This review aims to provide a guidance of finding abundant and cost‐effective precursors, green, simple and sustainable production processes to prepare coal‐based carbon dots, and make further efforts to exploit the application of carbon dots in broader fields. In this review, the latest research progress in the selection of carbon dots precursors (raw coal and its derivatives), preparation processes, physicochemical properties and applications (energy, catalytic, sensing, bioimaging, environmental pollutants monitoring etc.) are summarized, which provides constructive ideas for the further development of low‐cost and commercialized multi‐functional coal based carbon dots.
Graphite-like structures have a significant effect on the conversion of coal to carbon materials. To observe and analyze the different kinds of structures in thermally altered coal, HRTEM and XRD were employed in this work. Results showed that two different kinds of structures, aromatic clusters and graphite-like structures, could be distinguished in all thermally altered coal samples, even in a thermally altered coal sample having a Ro of 2.45%. The HRTEM images showed that aromatic clusters were made up of aromatic layers with different dimensions and directions. Some of the aromatic clusters showed a ringed arrangement, which is a benefit for both vertical stacking and lateral extension. The La/Lc value of aromatic clusters is smaller than 1, and the d of aromatic clusters is about 0.40 nm. Graphite-like structures are in the form of extended, multi-layered, uni-directional structural units. Compared with the aromatic clusters, graphite-like structures have obviously smaller interlayer spacing, more layers, larger extended size, and larger stacking height. The La/Lc of graphite-like structures is much larger than 1. All chemical structural parameters of the whole coal calculated from XRD data are between those of aromatic cluster and graphite-like structure, indicating that structural characteristics calculated by XRD are a mixture of both aromatic cluster and graphite-like structure. The genesis of different kinds of structures is related to heat, because the in situ-heating HRTEM showed that the aromatic layers transformed in different ways after heating. Surface layers transformed towards the graphite-like structure, while internal aromatic layers formed the aromatic clusters.
A metal-assisted microwave treatment that converting raw coal powders into nano-graphite is presented. Specifically, four major factors are identified for successful conversion: (1) high temperature; (2) reducing environment; (3) catalyst; and (4) microwave radiation. Specifically, it is determined that the combination of the carbon sources (raw coal powders), the high temperature (microwave induced electric sparking), the reducing environment (the Ar/H2 mixture), the catalyst (Cu foil), with the microwave radiations can generate nano-graphites. This novel approach utilizes the sparking induced by the microwave radiation on the fork-shape metal foils to generate high temperature (> 1000 ºC) within few seconds. The small thermal load makes this method cost effective and has potential for higher temperature using metals with higher melting temperature. Refinement of this technique is possible to yield a higher quality and quantity of nano-graphite materials for a wider range of applications.
Carbon nanotube assemblies with controlled morphology and tailored architecture offer great potentials for myriad applications, but strategies for their production have remained a significant challenge. Here, we proposed a novel and simple microconfined-annealing strategy, in which a Pickering microdroplet patterned method and unique pyrolysis-stimulated-transformation processes were coupled unprecedentedly, for the fabrication of spherical nitrogen-doped carbon nanotube assemblies (NCNTA). Based on this strategy, the as-prepared superstructures not only retained the micrometer-size and well-defined morphology of the initial Pickering droplets, but also derived a hierarchical pomegranate-like structure where numerous interconnected NCNT particles were encapsulated by a carbon crust. More importantly, the interior architectures were shown to be manipulated through controlling synthesized parameters. Owing to the unique structure and composition of these assemblies, the yielded superstructures exhibited excellent performance and good recyclability in heterogeneous catalysis applications. This synthetic strategy provides new routes to access other micro- or macroscopic materials with novel structures and paves the way to expand their potential applications.
In this paper, the changes in solid-phase carbon structure and the formation of carbon nanotubes in the process of K-catalyzed pyrolysis of bituminous coal were investigated. The results showed that the content of carbon nanotubes in K-catalyzed coal pyrolysis products increased with the extension of residence time. When the residence times were 0, 30 and 90 min, the yields of carbon nanotubes in the coal pyrolysis products were 1.98 wt%, 6.85 wt% and 10.16 wt%, respectively. It was found that the aromatic carbon CC, CH and ether carbon C-O-C structures in coal were the main carbon sources for the growth of carbon nanotubes. The probable growth mechanism of carbon nanotubes in the process of K-catalyzed coal pyrolysis was proposed to be as follows: aromatic CC and CH structures in coal convert K components such as K2CO3 and K2O into metal K, and then metal K converts carbon atoms in the ether bond C-O-C structure into carbon atoms or clusters, which generate carbon nanotubes under the action of Fe catalyst particles in coal. This method provides a new strategy for the simultaneous high-value utilization of coal resources and macroscopic, low-cost preparation of carbon nanotubes.
Although the synthesis of carbon nanotubes from coal can efficiently reduce the cost of preparing these materials, the effect of the primary minerals present in coal (e.g., Fe-containing siderite) on the growth of these structures has not been studied in depth. In this study, we used a bituminous coal containing siderite and investigated the changes of the original siderite phase and the growth mechanism of carbon nanotubes during a KOH-catalyzed coal pyrolysis process. The results shown that the primary Fe minerals played an important role in the formation of carbon nanotubes during coal pyrolysis. During the KOH-catalyzed pyrolysis of coal, the Fe present in the raw material migrated from the bulk to the surface of the coal particles, and enriched in some areas of the surface of the coal particle. KOH-catalyzed coal pyrolysis had a significant effect on the formation of micropores and the increase of specific surface area and pore volume in coal. The primary siderite in coal and the catalytic growth of carbon nanotubes, in line with the following mechanism: FeCO3 → α-Fe → Fe3C + Graphite → carbon nanotubes. This study can provide new ideas for the utilization of low-rank coal resources rich in Fe mineral components.
Coal has been employed as both significant energy supply and resource for the production of modern chemicals and novel carbon materials. Here, we present the synthesis of watermelon-like metallic Co/graphene hybrids with coal as starting material by approaches of catalytic graphitization, electrochemical exfoliation and in-situ functionalization. The ([BMIm]2[CoCl4]) ion liquid acted as both electrochemical exfoliation electrolyte and active dopant for the catalyst preparation. It is exhibited that the CoCl4--based intercalator could be effectively expanded into the gallery region of graphitized coal and resulted exfoliation of graphene-like nanocarbons. Interestingly, the absorbed Co ligands could be converted into watermelon-like metallic Co encapsulated by 1-Butyl-3-methylimidzolium ligands derived carbons. The electrochemical performance of [email protected] catalyst exhibited superior ORR activity to benchmark Pt-C with excellent half-wave potential, higher current density, direct four-electron pathway, superior methanol tolerance and stability. This work provides an alternative methodology for the production of graphene-like functional nanocarbons from coal with promising potential in energy conversion application.
The topic of this chapter is the synthesis of both aligned and unaligned carbon nanotube bulk ensembles by different methods such as electric arc discharge, laser ablation and chemical vapor deposition methods. First, general requirements for the CNTs synthesis are introduced. Utilization of different types of nucleation centers for nanotube synthesis as well as the role of CNT growth promoters and inhibitors is reviewed. Particular attention is paid to CVD methods which are most easily scalable, they offer a relatively good control over synthesis conditions and a high quality of as produced CNTs. Two general approaches for formation of catalyst for the CVD nanotube synthesis are discussed, namely methods utilizing pre-deposited catalysts or their precursors and methods exploiting an injection of catalyst precursors during the nanotube synthesis. Examples of breakthrough synthesis approaches, fundamental studies and those with best known results are given. The different nanotube fabrication methodologies are reviewed and discussed in details. This may assist readers to select the proper method and synthesis conditions with regards to nanotube targeted application.
In the present work, a novel method has been proposed, which can be used for generating carbon nanotubes (CNTs) using coal as the raw material and potassium hydroxide as the catalyst precursor. The results of Fourier Transform Infrared (FTIR) spectroscopy indicated that the groups of –CH3, –CH2 contained in the coal gradually disappeared during the potassium catalyzed pyrolysis. Raman analysis showed that the graphitization degree of catalytic pyrolysis products of raw coal was high, and the ratio of the intensities of G and D peaks (IG/ID) was 3.0. The results of Scanning Electron Microscope (SEM) showed that there were many CNTs in the product. The Transmission Electron Microscopy (TEM) showed that these CNTs had different shapes (linear or curved) and have good graphite crystal structure with a wall number of 18–65 layers and a diameter of 20–155 nm. The potassium catalyst has the dual function of catalyzing the formation of CNTs and etching large molecular structure to generate carbon source. The formation process of CNTs is as follows: coal takes pyrolysis to produce small carbon-containing molecules such as CH4, and the small carbon-containing molecules formed CNTs through catalytic cracking under the action of catalyst. A “stepwise growth” model of CNTs was established.
The impact of pressure on the carbon structure of a Chinese bituminous coal was investigated using a pressurized entrained-flow reactor in the temperature and pressure ranges of 700-900 oC and 0.1-4.0MPa, respectively. Pyrolysis pressure had a significant influence on the physiochemical and carbon structure of chars. The specific surface area and the swelling ratio of chars reached their highest values at 1.0MPa. Fourier transform infrared spectroscopy (FTIR) analysis showed that higher pressures enhanced the decomposition of functional groups in chars. Raman spectroscopy analysis results revealed that at elevated pressures, the organic matrix and functional groups were removed from the char structure, leading to higher ordering of the carbon structure. During X-ray diffraction (XRD) analysis, parameters such as the stacking height (Lc), interlayer spacing (d002) and lateral size of the graphite structures (La) were used to evaluate the graphitic structures in chars. The results showed an increase in Lc, La, and the average number of graphene sheets with pyrolysis pressure, indicating a more ordered carbon structure at elevated pressures. The d-spacing of char was in the range of 3.34-3.37 Å, similar to typical graphitic structures.
The paper shows the possibility of recycling food-type polymeric material in an ultradisperse powdered carbon product. The process is realized in the plasma of a direct current (DC) arc discharge, initiated in an open air between graphite electrodes. According to X-ray diffractometry, the product consists of 21.7% of graphite and 78.3% of X-ray amorphous fraction. The product is represented by rounded particles with average sizes less than 100 nm. The maximum particle size distribution is in the range from 50 nm to 75 nm.
Various techniques for the synthesis of carbon nanotubes (CNTs) are being developed to meet an increasing demand as a result of their versatile applications. Swirled floating catalyst chemical vapour deposition (SFCCVD) is one of these techniques. This method was used to synthesise CNTs on a continuous basis using acetylene gas as a carbon source, ferrocene dissolved in xylene as a catalyst precursor, and both hydrogen and argon as carrier gases. Transmission electron microscopy analyses revealed that a mixture of single and multi-wall carbon nanotubes and other carbon nanomaterials were produced within the pyrolytic temperature range of 900-1 100°C and acetylene flow rate range of 118-370 ml rnin -1. Image comparison of raw and purified products showed that low contents of iron particles and amorphous carbon were contained in the synthesised carbon nanotubes. Diamond films were produced at high ferrocene concentration, hydrogen flow rate and pyrolysis temperatures, while carbon nanoballs were formed and attached to the surface of the CNTs at low ferrocene content and low pyrolysis temperature.
Multi-walled carbon nanotubes (MWCNTs) were grown by plasma-enhanced chemical vapor deposition
(PECVD) in a bell jar reactor. A mixture of methane and hydrogen (CH4/H2) was decomposed
over Ni catalyst previously deposited on Si-wafer by thermionic vacuum arc (TVA) technology.
The growth parameters were optimized to obtain dense arrays of nanotubes and were found
to be: hydrogen flow rate of 90 sccm; methane flow rate of 10 sccm; oxygen flow rate of 1 sccm;
substrate temperature of 1123 K; total pressure of 10 mbar and microwave power of 342 Watt.
Results are summarized and significant main factors and their interactions were identified. In addition
a computational study of nanotubes growth rate was conducted using a gas phase reaction
mechanism and surface nanotube formation model. Simulations were performed to determine the
gas phase fields for temperature and species concentration as well as the surface-species coverage
and carbon nanotubes growth rate. A kinetic mechanism which consists of 13 gas species, 43 gas
reactions and 17 surface reactions has been used in the commercial computational fluid dynamics
(CFD) software ANSYS Fluent. A comparison of simulated and experimental growth rate is presented
in this paper. Simulation results agreed favorably with experimental data.
Microstructures in cathode deposits formed during fullerene production by electrical arcing in helium have been examined in detail. This has provided new information about the mechanisms by which nanobodies (nanotubes and nanoparticles) and pyrolytic carbon are deposited. Nanobodies and pyrolytic carbon form independently; the former probably grow in the plasma then deposit on the electrode but much of the latter deposits directly on the electrode surface.
We present a method of producing carbon nanotubes by means of the thermal plasma decomposition of methane in an arc-jet plasma of high temperature (5000–20,000 K). Carbon nanotubes are produced under a floating condition by introducing methane and a mixture of Ni–Y powders into the arc-jet plasma flame generated by a non-transferred plasma torch. Material evaluations of the synthesized product by transmission electron microscopy (TEM) and scanning electron microscopy (SEM) reveal that the growth rate of carbon nanotubes is very high, and that the multi-walled carbon nanotubes of high purity are mainly produced. Since this process is continuously operable and easily scalable, it is expected to be a promising technique for large-scale commercial production of carbon nanotubes.
A new modification of the gas discharge method for fullerene production is developed. Powdered amorphous carbon particles admitted into the flowing plasma of a plasmatron are used as a source of carbon atoms, in distinct from the conventional approach, where this aim is reached through the thermal vaporization of a graphite anode. The fullerene yield vs carbon black feeding rate has a smooth maximum, reaching about 2%. A physical model for vaporization of a small carbon particle in a weakly ionized plasma is built, which allows one to establish the interconnection between the time taken for vaporization of a particle, its size and the plasma temperature. Estimations based on this interconnection show that the effective vaporization of particles of micron size is reached using He or Ar gas carrier flowing with velocity of about 100 cm/s through the plasmatron channel of about 10 cm in length. The results of preliminary experiments are in agreement with those estimations. The main advantages of the proposed approach relate to continuous input of carbon feedstock materials into plasma zone, relatively low energy cost of carbon vaporization and usage of low cost carbon black produced from waste hydrocarbons.
A number of plasma arcing experiments have been carried out using naphthalene as fill in hollow graphite anodes in order to simulate the way fullerenes might be formed from polycyclic hydrocarbons in coal. The results show that naphthalene in the plasma arc fringe increases the C-70 to C-60 fullerene ratio in the product soot. The most probable explanation is that naphthalene is more readily incorporated into the C-70 fullerene structure because two aromatic rings together can be accommodated. C-60 fullerene may incorporate naphthalene, but only after a six to five membered ring rearrangement. It is generally believed that fullerenes are constructed from single C1 or double C2 carbon units when graphite is used as the anode. The results offer strong evidence that fullerenes can be produced via processes involving larger primary fragments when naphthalene is present in the anode.
Graphite has normally been used to synthesise fullerenes and nanotubes. However, coal is a cheaper and more suitable industrial material. Because coal is a molecular solid, unlike graphite, the mechanism by which fullerene and nanotubes are formed is different. Moreover, other products such as polyaromatic hydrocarbons (PAHs) and microfibres are also formed. In this review, the mechanism of formation of fullerene and nanotubes from coal is discussed. It is shown that the pathway involved is other than through the C1 intermediate route. The influence of other elements in coal such as hydrogen, oxygen, sulfur and iron is also discussed. It appears that, hydrogen, oxygen, iron and sulfur affect the yield and type of fullerenes and nanotubes formed.
A method is reported for controlling the diameter of single-walled carbon nanotubes (SWCNTs) during the electric-arc-discharge process. Using argon as inert atmosphere provides smaller diameters as compared with those when pure helium is used. Varying the gas mixture from argon to helium changes the diameter distribution to higher values. A linear fit of the average diameter shows a 0.2 Å diam decrease per 10% increase in the argon–helium ratio. © 2001 American Institute of Physics.
Encapsulation of foreign materials within a hollow graphitic cage was carried out for rare-earth and iron-group metals by using an electric arc discharge. The rare-earth metals with low vapor pressures, Sc, Y, La, Ce, Pr, Nd, Gd, Tb, Dy, Ho, Er, Tm, and Lu, were encapsulated in the form of carbides, whereas volatile Sm, Eu, and Yb metals were not. For iron-group metals, particles in metallic phases (α -Fe, γ -Fe; hep-Co, fcc-Co; fcc-Ni) and in a carbide phase (M3C, M = Fe, Co, Ni) were wrapped in graphitic carbon. The excellent protective nature of the outer graphitic cages against oxidation of the inner materials was demonstrated. In addition to the wrapped nanoparticles, exotic carbon materials with hollow structures, such as single-wall nanotubes, bamboo-shaped tubes, and nanochains, were produced by using transition metals as catalysts.
First- and second-order Raman spectra of carbon nanotubes produced in helium and argon atmospheres at a pressure ranging from 11 to 92 kPa by are discharge have been measured and compared with each other. The position and bandwidth of the spectral lines depend on the kind of inert gases and their pressure. The Raman spectra of the nanotubes produced in argon gas atmosphere are much more similar to that of polycrystalline graphite than those of the nanotubes produced in helium gas atmosphere. The position and bandwidth of nanotube Raman peaks change with gas pressure in are discharge because different diameter distribution of nanotubes is produced at different inert gas pressure. The Raman spectra of nanotubes produced at high pressure is much more like that of graphite than those produced in lower pressure.
Traditional data-oriented programming languages such as dataflow languages and stream languages provide a natural abstraction for parallel programming. In these languages, a developer focuses on the flow of data through the computation and these systems free the developer from the complexities of low-level, thread-oriented concurrency primitives. This simplification comes at a cost --- traditional data-oriented approaches restrict the mutation of state and, in practice, the types of data structures a program can effectively use. Bamboo borrows from work in typestate and software transactions to relax the traditional restrictions of data-oriented programming models to support mutation of arbitrary data structures.
We have implemented a compiler for Bamboo which generates code for the TILEPro64 many-core processor. We have evaluated this implementation on six benchmarks: Tracking, a feature tracking algorithm from computer vision; KMeans, a K-means clustering algorithm; MonteCarlo, a Monte Carlo simulation; FilterBank, a multi-channel filter bank; Fractal, a Mandelbrot set computation; and Series, a Fourier series computation. We found that our compiler generated implementations that obtained speedups ranging from 26.2x to 61.6x when executed on 62 cores.
A new technique for the synthesis of carbon nanotubes from coal is introduced in this paper. In this process, coal is selected as the raw material to injected into plasma jet directly, nanotubes are formed on the reactor wall. The metal elements contained in parent coal such as Cu, Al act as the catalyst. This technique is different from the traditional arc discharge process and has the advantages of easy and steady operation and low cost of raw material, so it is an attractive process.
Carbon nanotubes represent one of the most exciting research areas in modern science. These molecular-scale carbon tubes are the stiffest and strongest fibres known, with remarkable electronic properties, and potential applications in a wide range of fields. Carbon Nanotube Science is the most concise, accessible book for the field, presenting the basic knowledge that graduates and researchers need to know. Based on the successful Carbon Nanotubes and Related Structures, this new book focuses solely on carbon nanotubes, covering the major advances made in recent years in this rapidly developing field. Chapters focus on electronic properties, chemical and bimolecular functionalisation, nanotube composites and nanotube-based probes and sensors. The book begins with a comprehensive discussion of synthesis, purification and processing methods. With its full coverage of the state-of-the-art in this active research field, this book will appeal to researchers in a broad range of disciplines, including nanotechnology, engineering, materials science and physics.
This chapter reviews some important studies on the use of carbon nanomaterials in optical limiting and organic PV devices. C60 and CNTs used in the optical limiters as a form of either suspension or solution showed different nonlinear optical behavior. Although C60 suspensions limit transmitted light by nonlinear scattering, C60 solutions showed nonlinear absorption mechanism. CBS as a benchmark material has limited flexibility because of the lack of chemical variations of carbon black even though a simple and inexpensive preparation makes it attractive to commercial applications. On the contrary, C60 and CNT can be chemically modified and composited with different materials to allow the construction of solid-state optical limiting devices. Current organic solar cell technology requires highly conductive EA nanomaterials to promote exciton dissociation at the interface between the ED organic material, and the nanomaterials. In the case of bulk dispersed heterojunction device, there is a conductive carrier path percolated through organic matrix to electrons freed from excitons. Although there are many ongoing research projects on the stability of composite materials with carbon nanomaterials. New architecture suggested for organic solar cells with improved performance requires more advanced engineering of the carbon nanomaterials.
We have demonstrated that the production of carbon nanotubes in large quantities is possible with inexpensive coal as the starting carbon source by the arc discharge technique. It has been found that a large amount of carbon nanotubes of good quality can be obtained in the cathode deposits in which carbon nanotubes are present in nest-like bundles. For the growth of carbon nanotubes, the buffer gas pressure in the reactor is one of the crucial factors. The mineral matter in raw coals may also play an important part in the formation process of carbon nanotubes.
In the synthesis of carbon nanotubes from ethylene decomposition by a Fe/Mo/Al2O3 catalyst at 823 K, the long and continuous coaxial carbon–metal nanowires up to 540 nm is observed. And for the first time, it is observed that the coaxial carbon–metal nanowires can grow in tip and base growth mode simultaneously. A detailed formation mechanism is proposed, where the aggregation of metal particles, lift-up of nanotubes obeying different growth modes and the deformation of metal particles by nanotubes are considered as the necessary steps for the formation of the nanowires.
A method to synthesize high-quality carbon nanotubes (CNT) was developed using the carbon atoms generated from alcohols or hydrocarbons by thermal plasma jet (TPJ). The method is a continuous process and the CNTs were multi-walled, well graphitized and relatively pure, and did not contained any metal. The raw carbon soot produced under proper conditions contained about 80% high-quality CNTs. The method is a continuous process and the carbon source was easily atomized, and economical large-scale production could be possible.
Carbon nanotube is one of the most talked about materials in recent years due to its unique properties and potential applications in different fields. Out of different techniques, catalytic chemical vapour deposition in a fluidized bed is the most promising technique for bulk production of this exotic material. The objectives of this review are to bring out the science and technology behind this process, the present commercial scenario and to draw a future roadmap. We have critically examined the published literature on the nanoparticle fluidization, different forces involved in it and the hydrodynamics of a nano-agglomerate fluidized bed. The importance of use of discrete elemental method and computational fluid dynamics simulation in the fluidization of carbon nanotubes has also been highlighted. Different preparation routes of catalyst materials have been compiled. The reaction and growth mechanisms of nanotubes, including modeling have been discussed. The data on the effects of different process parameters on the quality and quantity of nanotubes have been critically analyzed. It has been indicated that the available data are scattered in nature and further understanding in the mechanism is required in order to find out the rate controlling step(s) and scale-up of the process. The present commercial scenario of carbon nanotube market has been depicted. At the end, based on the present knowledge gaps, future roadmaps have been suggested.
Here, we review part of the work carried out in our laboratories on carbon nanotube functionalization. Both covalent (sidewall derivatization) and non-covalent (using pi-pi interactions) functionalization have been used to solubilize carbon nanotubes (NTs). The combination of NTs with various electron donors, mainly using the supramolecular approach, led to a new generation of donor-acceptor nanohybrids which can be used for the development of carbon-based photovoltaic cells. Covalent functionalization has been successfully applied for preparation of water soluble nanotubes and further derivatization of the nanotubes with bioactive molecules hold great promise for application in drug, vaccine and gene delivery. Copyright (c) 2006 John Wiley & Sons, Ltd.
The growth mechanism of Y-junction carbon nanotubes (CNTs) prepared by floating catalyst method has been investigated by transmission electron microscopy (TEM). The branch of Y-junction CNT is much shorter than the stem CNT, and the trace of metal particle is observed clearly along the branch carbon nanotube. We present several evidences for a metal particle catalytic growth mechanism. A simple growth model was built to describe the growth process of Y-junction carbon nanotubes.
We have synthesized single-layer carbon nanotubes by co-vaporizing cobalt with carbon in an are fullerene generator and have identified conditions that lead to high yields. The diameter distribution of the tubes and their morphologies are studied using transmission electron microscopy. For nanotubes produced using cobalt and carbon, the tube diameters range from 1 to 2 nm with distribution peaks at 1.3 and 1.5 nm. When sulfur is added to the carbon and cobalt, production of single-layer nanotubes is enhanced and the tubes have a wider range of diameters (from 1 to 6 nm). The diameter distribution for these nanotubes shows prominent peaks al 1.3 and 1.5 nm and additional maxima at 2.7 and 3.6 nm. Cobalt-containing crystallites, some encapsulated in graphitic polyhedra, are produced with the nanotubes and are found in the soot away from the cathode.
This review covers the results obtained in carbon nanotube synthesis by chemical vapor deposition. Parameters such as catalysts, supports, carbon precursors, reaction time, temperature and gas flow rates that are used in the production of carbon nanotubes are discussed throughout the text. Purification of the synthesized carbon nanotubes and methods utilized for cost reduction were also explored.
Sulfur is present an an impurity in various industrial feedstocks and is generally regarded as a catalyst poison; however, controlled poisoning of metals by sulfur can improve both reactivity and selectivity. The authors have attempted to develop an understanding of the interplay between sulfur adsorption and carbon deposition reactions by monitoring not only the gas-phase products but also the amount of filamentous carbon deposited from the interaction of sulfur-contaminated cobalt particles with ethylene/hydrogen mixtures. Pretreatment of cobalt in low levels (4-100 ppm) of H[sub 2]S was found to dramatically increase the weight percentage of carbon filaments produced during the reaction, from 4.5 (without sulfur treatment) to 70%. In contrast, when the metal was pretreated at higher H[sub 2]S levels (>500 ppm) or when the sulfide was added continuously in the hydrocarbon feed at concentrations of >60 ppm the catalytic activity was completely suppressed. Carbon filaments produced on uncontaminated cobalt particles were found to be highly graphitic in nature, and this degree of structural perfection decreased as sulfur was added to the system. In addition, it was apparent that sulfur could induce fragmentation of the powdered catalyst, a feature which may provide some new insights into the understanding of redispersion phenomena of sintered metal particles. 41 refs., 9 figs., 2 tabs.
Arc/graphite, laser ablation and CVD are three main methods for the production of carbon nanotubes (CNTs). A free coal-based or graphite electrodes method was explored in our lab. In this method, coal powder was directly injected into arc plasma jet instead of arc evaporation of coal-based electrodes, so we called it coal/arc-jet process. It is found that the Cu nano-particles sputtered from copper electrodes played an important role of catalyst for the synthesis of CNTs. Three metal particles (Fe, Co, Cu) with grain size of 120 mesh were mixed into coal powder and injected into plasma jet, respectively. It is found that the yield of CNTs was improved evidently. The difference of their effectiveness of catalysis was discussed. Under the condition of thermal plasma jet with initial temperature of 3700K, coal was cracked into aromatic fragments, carbon free radicals and light hydrocarbons. Meanwhile, metallic particles were vaporized and then condense to nano-droplet that was the active site for CNTs growth. The generation of carbon precursor and “preparation” of metallic nano-particles was finished within one stage.
The synthesis of branched carbon nanotubes (BCNT) from coal by arc-discharge with copper as a catalyst, was reported. The average erosion rate of graphite/coal composite anode is estimated to be 0.34 g/min by measuring the lost weight of anode in an experimental cycle. The X-photon energy dispersive spectroscopy (X-EDS) analysis revealed that theses catalyst particles are copper-containing species. The results show that BCNTs with a purity of ca. 70% can be obtained in large quantity under suitable experimental conditions.
The production of amorphous carbon nanotubes by temperature controlled DC arc discharge was discussed. The temperature was controlled by a thermocouple during heating and arc discharge. The soot of the inner wall of the DC arc discharge furnace was investigated using X-ray diffraction with Cu K-α target and TEM and HRTEM. The results show that when temperature in the furnace is above 300 °C, CNTs are produced on the walls on a large scale.
Carbon nanotubes and nanoparticles were synthesized from Chinese coals. Si-containing materials in the coals were completely encapsulated within the graphitic cages during the arc evaporation of coal-based electrodes.
This review analyses the literature from the early 1990s until the beginning of 2003 and covers the use of carbon nanotubes (CNT) and nanofibers as catalysts and catalysts supports. The article is composed of three sections, the first one explains why these materials can be suitable for these applications, the second describes the different preparation methods for supporting metallic catalysts on these supports, and the last one details the catalytic results obtained with nanotubes or nanofibers based catalysts. When possible, the results were compared to those obtained on classical carbonaceous supports and explanations are proposed to clarify the different behaviors observed.
Plasma enhanced chemical vapour deposition (PECVD) has been widely discussed in the literature for the growth of carbon nanotubes (CNTs) and carbon nanofibres (CNFs) in recent years. Advantages claimed include lower growth temperatures relative to thermal CVD and the ability to grow individual, free-standing, vertical CNFs instead of tower-like structures or ensembles. This paper reviews the current status of the technology including equipment, plasma chemistry, diagnostics and modelling, and mechanisms. Recent accomplishments include PECVD of single-walled CNTs and growth at low temperatures for handling delicate substrates such as glass.
Carbon nanostructures including carbon nanoparticles and tubular carbon nanostructures were synthesized by microwave plasma chemical vapor deposition. The nanoparticles were synthesized from the mixture of H2 and CH4 and the tubular nanostructures were obtained from the mixture of N2 and CH4. The tubular nanostructures are composed of nanotubes and nanofibres. The size of the nanoparticles is in the range of several tens of nanometer to more than 200 nm. Raman spectra indicate a graphitic structure both for the carbon nanoparticles and tubular nanostructures. Catalyst is needed for growing the carbon nanostructures.
From the Foreword, written by legendary nano pioneer M. Meyyappan, Chief Scientist for Exploration Technology NASA Ames Research Center, Moffett Field, California, USA: "there is critical need for a book to summarize the status of the field but more importantly to lay out the principles behind the technology. This is what Professor Arvind Agarwal and his co-workers have done here." Carbon Nanotubes: Reinforced Metal Matrix Composites reflects the authors' desire to share the benefits of nanotechnology with the masses by developing metal matrix carbon nanotube (MM-CNT) composites for large-scale applications. Multiwall carbon nanotubes can now be produced on a large scale and at a significantly reduced cost. The book explores potential applications and applies the author's own research to highlight critical developmental issues for different MM-CNT composites-and then outline novel solutions. With this problem-solving approach, the book explores: • Advantages, limitations, and the evolution of processing techniques used for MM-CNT composites • Characterization techniques unique to the study of MM-CNT composites-and the limitations of these methods • Existing research on different MM-CNT composites, presented in useful tables that include composition, processing method, quality of CNT dispersion, and properties • The micro-mechanical strengthening that results from adding CNT • The applicability of micro-mechanics models in MM-CNT composites • Significance of chemical stability for carbon nanotubes in the metal matrix as a function of processing, and its impact on CNT/metal interface and mechanical properties • Computational studies that have not been sufficiently covered although they are essential to research and development • The critical issue of CNT dispersion in the metal matrix, as well as a unique way to quantify CNT distribution and subsequently improve control of the processing parameters for obtaining improved properties Carbon Nanotubes: Reinforced Metal Matrix Composites paints a vivid picture of scientific and application achievements in this field. Exploring the mechanisms through which CNTs are enhancing the properties of different metal-based composites, the authors provide a roadmap to help researchers develop MM-CNT composites and choose potential materials for use in emerging areas of technology. Instructors We provide complimentary e-inspection copies of primary textbooks to instructors considering our books for course adoption.
Carbon Nanotubes are one the most important materials of future. Discovered in 1991, they have reached a stage of attracting the interests of many companies world wide for their large scale production. They possess remarkable electrical, mechanical, optical, thermal and chemical properties, which make them a perfect "fit" for many engineering applications. In this paper various methods of production of carbon nanotubes are dis-cussed outlining their capabilities, efficiencies and possible exploitation as economic large scale production methods. Chemical vapor disposition (CVD) is proposed as a potential method for economic large scale production of carbon nanotubes due to its relative simplicity of operation, process control, energy efficiency, raw materials used, capability to scale up as large unit operation, high yield and purity.
Coal conversion in arc plasma with an initial temperature of 3700 K is complex; a new conversion mechanism is put forward in this article. The functions of pyrolysis and the interaction of active species containing plasma jets are the main factors for coal conversion under these conditions. This study indicates that when the coal feed rate is lower than 2.0 g/s, both pyrolysis and active species have evident contribution to coal conversion; the pyrolysis controls the coal conversion and the function of active species is very weak. It is also found that the coal feed rate has a large influence on coal conversion and the production of gas components.
Multiwalled carbon nanotubes (MWCNTs) have been produced with a DC arc-discharger in the presence of hydrogen, helium or hydrogen-helium mixtures using high gas pressures (60kPa-140kPa) and varying gas pressure ratios (10%-100% hydrogen in helium at 100kPa). Variation of He pressure hardly affected the cathode deposit formation while increased H-2 pressure resulted in an increase in chamber soot and cathode material formation but a relative decrease in the % MWCNT production. Varying H-2/He gas ratios at a constant total pressure of 100kPa revealed that increasing H-2 content gave increased cathode deposit formation because of a faster anode consumption rate as well as more total gaseous product formation. Further, a maximum MWCNT deposit was obtained from a 50150 gas mixture. GC-MS analysis of the gaseous products trapped from these reactions showed evidence for the presence of linear alkynes (ethyne, butyne, pentyne, hexyne etc.), benzene, naphthalene, anthracene, and their methylated analogues. The relative in-situ temperature of the reaction with the pure gases was monitored and revealed that the highest temperature was recorded for the reaction with 60kPa H-2, which also produced the maximum amount of MWCNTs (80%). Impure samples from the cathode deposit were analysed by TEM and showed that in the majority of cases rectangular closed-tipped nanotubes were synthesised, together with varying amounts of onion-like sheets and folded graphene sheets.
The issue of deposited carbon (DC) on a reactor wall during the production of acetylene by the coal/arc plasma process is a potential obstacle for the industrialization process. The formation mechanism of DC is very difficult to reveal because the high complexity of coal and the volatile matter. Combining with quenching technique, the methane, liquid petroleum gas and benzene were employed as the model materials to roughly act as the light gas, chain and aromatic subcomponents of volatile matter, and then the reasonable formation mechanism of DC was subtly speculated accordingly.
DC-Arc Discharge technique has been used to synthesize carbon nanotubes from super clean coal samples instead of graphite electrodes filled with metal catalysts. The adverse effect of the mineral matter present in coal may be, thus, avoided. The cathode deposits showed the presence of single walled carbon nanotubes as well, which are generally known to be formed only in presence of transition metal catalysts and lanthanides. The process also avoids the tedious purification treatments of carbon nanotubes by strong acids to get rid of metal catalysts produced as impurities along with nanotubes. Thus, coal may be refined and demineralized by an organorefining technique to obtain super clean coal, an ultra low ash coal which may be used for the production of carbon nanotubes. The residual coal obtained after the organorefining may be used as an energy source for raising steam for power generation. Thus, coal may afford its use as an inexpensive feedstock for the production of carbon nanotubes besides its conventional role as a fuel for power generation.
CARBON nanotubes1 are expected to have a wide variety of interesting properties. Capillarity in open tubes has already been demonstrated2–5, while predictions regarding their electronic structure6–8 and mechanical strength9 remain to be tested. To examine the properties of these structures, one needs tubes with well defined morphologies, length, thickness and a number of concentric shells; but the normal carbon-arc synthesis10,11 yields a range of tube types. In particular, most calculations have been concerned with single-shell tubes, whereas the carbon-arc synthesis produces almost entirely multi-shell tubes. Here we report the synthesis of abundant single-shell tubes with diameters of about one nanometre. Whereas the multi-shell nanotubes are formed on the carbon cathode, these single-shell tubes grow in the gas phase. Electron diffraction from a single tube allows us to confirm the helical arrangement of carbon hexagons deduced previously for multi-shell tubes1.
CARBON exhibits a unique ability to form a wide range of structures. In an inert atmosphere it condenses to form hollow, spheroidal fullerenes1–4. Carbon deposited on the hot tip of the cathode of the arc-discharge apparatus used for bulk fullerene synthesis will form nested graphitic tubes and polyhedral particles5–8. Electron irradiation of these nanotubes and polyhedra transforms them into nearly spherical carbon 'onions'9. We now report that covaporizing carbon and cobalt in an arc generator leads to the formation of carbon nanotubes which all have very small diameters (about 1.2 nm) and walls only a single atomic layer thick. The tubes form a web-like deposit woven through the fullerene-containing soot, giving it a rubbery texture. The uniformity and single-layer structure of these nanotubes should make it possible to test their properties against theoretical predictions10–13.