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C, Volume 8, Issue 1 (March 2022) – 19 articles

Cover Story (view full-size image): Electrical and applied voltage annealing has been shown to increase the electrical conductivity of carbon nanotube (CNT) fibers to make them better electrical conductors. A study of thermal annealing in a vacuum up to 800 °C was performed on smaller fiber sections along with a separate analysis of voltage annealing up to 7 V; both exhibited an optimal condition in the process as determined by a combination of two-point probe measurement with a nanoprobe, resonant Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). Scaled-up tests were then performed to translate these results into bulk samples inside a tube furnace, with similar results that indicate the potential for an optimized method of achieving a better conductor samples made from CNT fibers. View this paper
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Article
Low-Sulphur Vacuum Gasoil of Western Siberia Oil: The Impact of Its Structural and Chemical Features on the Properties of the Produced Needle Coke
C 2022, 8(1), 19; https://0-doi-org.brum.beds.ac.uk/10.3390/c8010019 - 17 Mar 2022
Viewed by 900
Abstract
The specific branches of industry utilize needle coke, a carbon form with a highly anisotropic structure. Searching for novel raw materials for its production is now rigorously studied. In the present work, we use low-sulfur gasoil for this purpose, namely its high-boiling fractions. [...] Read more.
The specific branches of industry utilize needle coke, a carbon form with a highly anisotropic structure. Searching for novel raw materials for its production is now rigorously studied. In the present work, we use low-sulfur gasoil for this purpose, namely its high-boiling fractions. We study their chemical and physicochemical parameters with the set of physicochemical and spectral methods. The data of FT-IR and UV-Vis spectroscopies with a phenomenological method (that allows assessing average electronic structure parameters) indicate that the gas oil of the West Siberian origin contains polycyclic aromatic hydrocarbons (PAHs) with 3–5 condensed benzene rings. The maximum amount of PAHs with molecular masses of 400–600 a.u. is contained in the fractions with boiling points higher than 450 °C. According to the data of polarized-light optical microscopy, the higher boiling point of the gasoil fraction the higher anisotropy of the produced coke. This occurs as a result of an increase in the amount of PAHs capable of condensation with the formation of a mesophase. Thus, low-sulfur gas oils from thermally processed West Siberian oil are promising raw materials for the production of needle coke in delayed coking processes. Full article
(This article belongs to the Section Carbon Materials and Carbon Allotropes)
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Review
Synthetic, Photosynthetic, and Chemical Strategies to Enhance Carbon Dioxide Fixation
C 2022, 8(1), 18; https://0-doi-org.brum.beds.ac.uk/10.3390/c8010018 - 15 Mar 2022
Viewed by 987
Abstract
The present human population is more than three times what it was in 1950. With that, there is an increasing demand for the consumption of fossil fuels for various anthropogenic activities. This consumption is the major source of carbon dioxide emission causing greenhouse [...] Read more.
The present human population is more than three times what it was in 1950. With that, there is an increasing demand for the consumption of fossil fuels for various anthropogenic activities. This consumption is the major source of carbon dioxide emission causing greenhouse effects leading to global warming. The dependency on fossil fuels around the globe is such that it would be hard to move away from it any time soon. Hence, we must work on strategies to improve carbon dioxide fixation as we are making advancements in clean energy technology. This review explores the natural carbon dioxide fixation pathways in plants and various microorganisms and discusses their limitations and alternative strategies. It explains what necessitates the exploration of synthetic pathways and discusses strategies and matrices to consider while evaluating various pathways. This review also discusses the recent breakthroughs in the field of nanosciences that could accelerate chemical methods of carbon dioxide fixation. Full article
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Article
Functionalization of Graphene by π–π Stacking with C60/C70/Sc3[email protected]80 Fullerene Derivatives for Supercapacitor Electrode Materials
C 2022, 8(1), 17; https://0-doi-org.brum.beds.ac.uk/10.3390/c8010017 - 11 Mar 2022
Viewed by 1048
Abstract
Non-covalent modification of graphene is one of the strategies used for enhancing its energy storage properties. Herein, we report the design and synthesis of a series of fullerene derivatives that are capable of assembly on graphene sheets by π–π stacking interactions. Newly synthesized [...] Read more.
Non-covalent modification of graphene is one of the strategies used for enhancing its energy storage properties. Herein, we report the design and synthesis of a series of fullerene derivatives that are capable of assembly on graphene sheets by π–π stacking interactions. Newly synthesized graphene-fullerene hybrid nanomaterials were characterized using spectroscopic and microscopic techniques. In order to determine the specific capacitance of obtained electrode materials galvanostatic charge-discharge measurements were performed. The obtained results allowed the determination of which fullerene core and type of substituent introduced on its surface can increase the capacitance of resulting electrode. Benefiting from introduced fullerene derivative molecules, graphene with naphthalene functionalized C70 fullerene showed specific capacitance enhanced by as much as 15% compared to the starting material. Full article
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Article
Temperature Dependence of Hydrogen Adsorption on Pd-Modified Carbon Blacks and Their Enthalpy-Entropy Changes
C 2022, 8(1), 16; https://0-doi-org.brum.beds.ac.uk/10.3390/c8010016 - 22 Feb 2022
Viewed by 917
Abstract
Metal-carbon composites have recently gained attention as potential hydrogen storage materials. In the present investigation, carbon blacks (CBs) with 0.6 mass %, 4.9 mass %, and 9.3 mass % of Pd were prepared to investigate the cooperative effect together with Pd and CB [...] Read more.
Metal-carbon composites have recently gained attention as potential hydrogen storage materials. In the present investigation, carbon blacks (CBs) with 0.6 mass %, 4.9 mass %, and 9.3 mass % of Pd were prepared to investigate the cooperative effect together with Pd and CB for hydrogen storage. The hydrogen adsorption isotherms were measured at 77 K, 98 K, 123 K, 148 K, 173 K, 223 K, and 273 K under mild pressures below 1 MPa. The lower temperature gave the higher hydrogen content. Almost all the hydrogen contents of Pd-modified CBs exceeded the sum of the adsorption contents of CB and the occluded amounts of the assumed hydride, PdH0.6. The highest hydrogen content was recorded for Pd 0.6 mass %-modified CB at 77 K. At temperatures above 77 K, CBs with the higher Pd contents adsorbed more hydrogen than Pd 0.6 mass %-modified CB, and they indicated an increase in the absolute values of adsorption enthalpy with the progress of adsorption. Pd was thought to be at first blocking deep potential sites, with accessibility to hydrogen acceptable sites gradually increasing as adsorption progressed. Full article
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Article
Carbon Composites—Graphene-Oxide-Catalyzed Sugar Graphitization
C 2022, 8(1), 15; https://0-doi-org.brum.beds.ac.uk/10.3390/c8010015 - 14 Feb 2022
Viewed by 1163
Abstract
Utilization of biopolymers to form graphitic carbons is challenged by their high oxygen content and resulting curved and defective carbon lamellae upon high-temperature heat-treatment. Two composites, one with graphene-oxide (GO) and the other with reduced graphene-oxide (rGO) as fillers, respectively, in a matrix [...] Read more.
Utilization of biopolymers to form graphitic carbons is challenged by their high oxygen content and resulting curved and defective carbon lamellae upon high-temperature heat-treatment. Two composites, one with graphene-oxide (GO) and the other with reduced graphene-oxide (rGO) as fillers, respectively, in a matrix of sugar, each for the same added 2.5 wt.%, exhibited different degrees of graphitization compared to pure sugar on its own. Reactive oxygen groups on GO contribute to reactive templating and crystallite formation. Under high-temperature heat-treatment, sugar, a well-known non-graphitizing precursor, is converted to graphitic carbon in the presence of GO. Possessing fewer oxygen groups, rGO forms two phases in the sugar matrix—a non-graphitic phase and a graphitic phase. The latter is attributed to the remaining oxygen on the rGO. Full article
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Article
Structural and Electrochemical Characteristics of Platinum Nanoparticles Supported on Various Carbon Carriers
C 2022, 8(1), 14; https://0-doi-org.brum.beds.ac.uk/10.3390/c8010014 - 14 Feb 2022
Viewed by 1006
Abstract
Graphene-like materials have attracted significant attention as alternative catalyst carriers due to the broad possibilities of changing their shape, composition, and properties. In this study we investigated the structural and electrochemical characteristics of platinum electrocatalysts supported on reduced graphene oxide (rGO), including those [...] Read more.
Graphene-like materials have attracted significant attention as alternative catalyst carriers due to the broad possibilities of changing their shape, composition, and properties. In this study we investigated the structural and electrochemical characteristics of platinum electrocatalysts supported on reduced graphene oxide (rGO), including those modified with amine functionalities, nitrogen heteroatoms (rGO-Am), and oxygen enriched (rGO-O). Synthesis of Pt nanoparticles (20 wt.%) on the graphene-like nanomaterials surface was carried out using a modified polyol procedure. The Pt20/rGO-Am showed a lower Pt nanoparticles size together with high Pt utilization and EASA values compared to rGO-supported catalysts and the Pt/C reference sample due to the uniform distribution of nucleation centers on the surface of graphene nanoparticles, and the greater ability of these centers to electrically bond with platinum. Full article
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Article
Compositing Fullerene-Derived Porous Carbon Fibers with Reduced Graphene Oxide for Enhanced ORR Catalytic Performance
C 2022, 8(1), 13; https://0-doi-org.brum.beds.ac.uk/10.3390/c8010013 - 11 Feb 2022
Viewed by 866
Abstract
Compositing all-carbon materials with distinct dimensions and structures has demonstrated the great potential to bring synergistic promotion to individual components for the electrocatalytic activity of oxygen reduction reaction (ORR). Fullerene-derived porous carbon fibers (FPCFs) offer unique one-dimensional (1D) nanostructures with abundant defects and [...] Read more.
Compositing all-carbon materials with distinct dimensions and structures has demonstrated the great potential to bring synergistic promotion to individual components for the electrocatalytic activity of oxygen reduction reaction (ORR). Fullerene-derived porous carbon fibers (FPCFs) offer unique one-dimensional (1D) nanostructures with abundant defects and a large specific surface area while graphene features two-dimensional (2D) nanostructures with fast electron transfer. Both carbon materials are promising alternatives to Pt-based electrocatalysts for ORR. Herein, a novel hierarchical composite ([email protected]) composed of FPCFs and reduced graphene oxide (rGO) is constructed by sonication-assisted mixing and high-temperature pyrolysis. When tested as an electrocatalyst for ORR, the 1D/2D [email protected] composite presents significantly enhanced performance compared to each individual component, indicating an eminent synergistic effect between FPCFs and rGO. The improved ORR performance of [email protected] is attributed to the unique hierarchical structure with abundant structural defects, a large specific surface area, and high porosity. Full article
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Article
Reduced Graphene Oxide—Polycarbonate Electrodes on Different Supports for Symmetric Supercapacitors
C 2022, 8(1), 12; https://0-doi-org.brum.beds.ac.uk/10.3390/c8010012 - 02 Feb 2022
Viewed by 1184
Abstract
Electrode materials for electrochemical capacitors or supercapacitors (SCs) are widely studied, as they are needed for the development of energy storage devices in electrical vehicles and flexible electronics. In the current work, a self-supported paper of reduced graphene oxide (rGO) with polycarbonate (PC) [...] Read more.
Electrode materials for electrochemical capacitors or supercapacitors (SCs) are widely studied, as they are needed for the development of energy storage devices in electrical vehicles and flexible electronics. In the current work, a self-supported paper of reduced graphene oxide (rGO) with polycarbonate (PC) (as rGO-PC composite) was prepared by simple vacuum filtration and low-temperature annealing. rGO-PC as a freestanding single electrode was studied in a three-electrode system and presented a capacitive energy storage mechanism. To fabricate SCs based on rGO-PC, flexible polyethylene terephthalate (PET) with layers of both Cu tape (Cu tape) and carbon tape (C tape) (PET/Cu/C), as well as PET covered by graphene ink (PET/GrI), were used as supports. Fabricated flexible symmetric SCs have shown similar behavior with a higher areal capacitance value than that on PET/Cu/C substrate. Full article
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Editorial
Acknowledgment to Reviewers of C in 2021
C 2022, 8(1), 11; https://0-doi-org.brum.beds.ac.uk/10.3390/c8010011 - 28 Jan 2022
Viewed by 690
Abstract
Rigorous peer-reviews are the basis of high-quality academic publishing [...] Full article
Article
Asymmetrical Cross-Sectional Buckling in Arc-Prepared Multiwall Carbon Nanotubes Revealed by Iodine Filling
C 2022, 8(1), 10; https://0-doi-org.brum.beds.ac.uk/10.3390/c8010010 - 27 Jan 2022
Viewed by 864
Abstract
We report the intercalation of iodine chains in highly crystalline arc-discharge multiwalled carbon nanotubes (MWCNTs), not in the central cavity but instead between the concentric graphene shells. High-resolution transmission electron microscopy demonstrated that the intercalation was asymmetric with respect to the longitudinal axis [...] Read more.
We report the intercalation of iodine chains in highly crystalline arc-discharge multiwalled carbon nanotubes (MWCNTs), not in the central cavity but instead between the concentric graphene shells. High-resolution transmission electron microscopy demonstrated that the intercalation was asymmetric with respect to the longitudinal axis of the nanotubes. This filling is explained through the existence of asymmetric intershell channels which formed as the tubes shrank upon cooling after growth. Shrinkage occurred because the geometrically constrained equilibrium intershell spacing was higher at growth than room temperature, due to the highly anisotropic coefficient of thermal expansion of graphite (or graphene stacks). Computational modelling supported the formation of such cavities and explained why they all formed on the same side of the tubes. The graphene shells were forced to bend outward, thereby opening aligned intergraphene nanocavities, and subsequently allowing the intercalation with iodine once the tube ends were opened by oxidative treatment. These observations are specific to catalyst-free processes because catalytic processes use too low temperatures, but they are generally applicable in geometrically closed carbon structures grown at high temperatures and so should be present in all arc-grown MWCNTs. They are likely to explain multiple observations in the literature of asymmetric interlayer spacings in multiple-shell graphenic carbon structures. Full article
(This article belongs to the Collection Feature Papers in the Science and Engineering of Carbons)
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Article
From Waste Plastics to Carbon Nanotube Audio Cables Viewed by 1230
Abstract
Carbon nanotubes (CNTs) have long been at the forefront of materials research, with applications ranging from composites for increased tensile strength in construction and sports equipment to transistor switches and solar cell electrodes in energy applications. There remains untapped potential still when it [...] Read more.
Carbon nanotubes (CNTs) have long been at the forefront of materials research, with applications ranging from composites for increased tensile strength in construction and sports equipment to transistor switches and solar cell electrodes in energy applications. There remains untapped potential still when it comes to energy and data transmission, with our group having previously demonstrated a working ethernet cable composed of CNT fibers. Material composition, electrical resistance, and electrical capacitance all play a strong role in the making of high-quality microphone and headphone cables, and the work herein describes the formation of a proof-of-concept CNT audio cable. Testing was done compared to commercial cables, with frequency response measurements performed for further objective testing. The results show performance is on par with commercial cables, and the CNTs being grown from waste plastics as a carbon source further adds to the value proposition, while also being environmentally friendly. Full article
(This article belongs to the Special Issue Frontier Applications of Carbon Nanotube-Based Materials)
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Article
The Influence of Hydrogen Passivation on Conductive Properties of Graphene Nanomesh—Prospect Material for Carbon Nanotubes Growing Viewed by 748
Abstract
Graphene nanomesh (GNM) is one of the most intensively studied materials today. Chemical activity of atoms near GNM’s nanoholes provides favorable adsorption of different atoms and molecules, besides that, GNM is a prospect material for growing carbon nanotubes (CNTs) on its surface. This [...] Read more.
Graphene nanomesh (GNM) is one of the most intensively studied materials today. Chemical activity of atoms near GNM’s nanoholes provides favorable adsorption of different atoms and molecules, besides that, GNM is a prospect material for growing carbon nanotubes (CNTs) on its surface. This study calculates the dependence of CNT’s growing parameters on the geometrical form of a nanohole. It was determined by the original methodic that the CNT’s growing from circle nanoholes was the most energetically favorable. Another attractive property of GNM is a tunable gap in its band structure that depends on GNM’s topology. It is found by quantum chemical methods that the passivation of dangling bonds near the hole of hydrogen atoms decreases the conductance of the structure by 2–3.5 times. Controlling the GNM’s conductance may be an important tool for its application in nanoelectronics. Full article
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Editorial
Hydrogenation and Dehydrogenation of Liquid Organic Hydrogen Carriers: A New Opportunity for Carbon-Based Catalysts Viewed by 735
Abstract
The development of a hydrogen-based economy is the perfect nexus between the need of discontinuing the use of fossil fuels (trying to mitigate climate change), the development of a system based on renewable energy (with the use of hydrogen allowing us to buffer [...] Read more.
The development of a hydrogen-based economy is the perfect nexus between the need of discontinuing the use of fossil fuels (trying to mitigate climate change), the development of a system based on renewable energy (with the use of hydrogen allowing us to buffer the discontinuities produced in this generation) and the achievement of a local-based robust energy supply system [...] Full article
(This article belongs to the Special Issue Carbon Materials for Physical and Chemical Hydrogen Storage)
Article
Revealing Hydrogen States in Carbon Structures by Analyzing the Thermal Desorption Spectra Cited by 1 | Viewed by 776
Abstract
An effective methodology for the detailed analysis of thermal desorption spectra (TDS) of hydrogen in carbon structures at micro- and nanoscale was further developed and applied for a number of TDS data of one heating rate, in particular, for graphite materials irradiated with [...] Read more.
An effective methodology for the detailed analysis of thermal desorption spectra (TDS) of hydrogen in carbon structures at micro- and nanoscale was further developed and applied for a number of TDS data of one heating rate, in particular, for graphite materials irradiated with atomic hydrogen. The technique is based on a preliminary description of hydrogen desorption spectra by symmetric Gaussians with their special processing in the approximation of the first- and the second-order reactions. As a result, the activation energies and the pre-exponential factors of the rate constants of the hydrogen desorption processes are determined, analyzed and interpreted. Some final verification of the results was completed using methods of numerical simulation of thermal desorption peaks (non-Gaussians) corresponding to the first- and the second-order reactions. The main research finding of this work is a further refinement and/or disclosure of poorly studied characteristics and physics of various states of hydrogen in microscale graphite structures after irradiation with atomic hydrogen, and comparison with the related results for nanoscale carbon structures. This is important for understanding the behavior and relationship of hydrogen in a number of cases of high energy carbon-based materials and nanomaterials. Full article
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Article
Experimental Volumetric Hydrogen Uptake Determination at 77 K of Commercially Available Metal-Organic Framework Materials Cited by 2 | Viewed by 948
Abstract
Storage is still limiting the implementation of hydrogen as an energy carrier to integrate the intermittent operation of renewable energy sources. Among different solutions to the currently used compressed or liquified hydrogen systems, physical adsorption at cryogenic temperature in porous materials is an [...] Read more.
Storage is still limiting the implementation of hydrogen as an energy carrier to integrate the intermittent operation of renewable energy sources. Among different solutions to the currently used compressed or liquified hydrogen systems, physical adsorption at cryogenic temperature in porous materials is an attractive alternative due to its fast and reversible operation and the resulting reduction in storage pressure. The feasibility of cryoadsorption for hydrogen storage depends mainly on the performance of the used materials for the specific application, where metal-organic frameworks or MOFs are remarkable candidates. In this work, gravimetric and volumetric hydrogen uptakes at 77 K and up to 100 bar of commercially available MOFs were measured since these materials are made from relatively cheap and accessible building blocks. These materials also show relatively high porous properties and are currently near to large-scale production. The measuring device was calibrated at different room temperatures to calculate an average correction factor and standard deviation so that the correction deviation is included in the measurement error for better comparability with different measurements. The influence of measurement conditions was also studied, concluding that the available adsorbing area of material and the occupied volume of the sample are the most critical factors for a reproducible measurement, apart from the samples’ preparation before measurement. Finally, the actual volumetric storage density of the used powders was calculated by directly measuring their volume in the analysis cell, comparing that value with the maximum volumetric uptake considering the measured density of crystals. From this selection of commercial MOFs, the materials HKUST-1, PCN-250(Fe), MOF-177, and MOF-5 show true potential to fulfill a volumetric requirement of 40 g·L−1 on a material basis for hydrogen storage systems without further packing of the powders. Full article
(This article belongs to the Special Issue Carbon Materials for Physical and Chemical Hydrogen Storage)
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Article
The X-ray, Raman and TEM Signatures of Cellulose-Derived Carbons Explained Viewed by 860
Abstract
Structural properties of carbonized cellulose were explored to conjugate the outcomes from various characterization techniques, namely X-ray diffraction (XRD), Raman spectroscopy, and high-resolution transmission electron microscopy. All these techniques have evidenced the formation of graphene stacks with a size distribution. Cellulose carbonized at [...] Read more.
Structural properties of carbonized cellulose were explored to conjugate the outcomes from various characterization techniques, namely X-ray diffraction (XRD), Raman spectroscopy, and high-resolution transmission electron microscopy. All these techniques have evidenced the formation of graphene stacks with a size distribution. Cellulose carbonized at 1000 and 1800 °C at a heating rate of 2 °C/min showed meaningful differences in Raman spectroscopy, whereas in XRD, the differences were not well pronounced, which implies that the crystallite sizes calculated by each technique have different significations. In the XRD patterns, the origin of a specific feature at a low scattering angle commonly reported in the literature but poorly explained so far, was identified. The different approaches used in this study were congruous in explaining the observations that were made on the cellulose-derived carbon samples. The remnants of the basic structural unit (BSU) are developed during primary carbonization. Small graphene-based crystallites inherited from the BSUs, which formerly developed during primary carbonization, were found to coexist with larger ones. Even if the three techniques give information on the average size of graphenic domains, they do not see the same characteristics of the domains; hence, they are not identical, nor contradictory but complementary. The arguments developed in the work to explain which characteristics are deduced from the signal obtained by each of the three characterization techniques relate to physics phenomena; hence, they are quite general and, therefore, are valid for all kind of graphenic materials. Full article
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Review
Carbon Nanomaterials for Theranostic Use Cited by 2 | Viewed by 913
Abstract
Based on statistics from the National Cancer Institute in the US, the rate of new cases of cancer is 442.4 per 100,000 men and women per year, and more than one-third do not survive the disease. Cancer diagnosis and treatment are the most [...] Read more.
Based on statistics from the National Cancer Institute in the US, the rate of new cases of cancer is 442.4 per 100,000 men and women per year, and more than one-third do not survive the disease. Cancer diagnosis and treatment are the most important challenges in modern medicine. The majority of cancer cases are diagnosed at an early stage. However, the possibility of simultaneous diagnosis and application of therapy (theranostics) will allow for acceleration and effectiveness of treatment. Conventional chemotherapy is not effective in reducing the chemoresistance and progression of various types of cancer. In addition, it causes side effects, which are mainly a result of incorrect drug distribution. Hence, new therapies are being explored as well as new drug delivery strategies. In this regard, nanotechnology has shown promise in the targeted delivery of therapeutics to cancer cells. This review looks at the latest advances in drug delivery-based diagnosis and therapy. Drug delivery nanosystems made of various types of carbon (graphene, fullerenes, and carbon nanotubes) are discussed. Their chemical properties, advantages, and disadvantages are explored, and these systems are compared with each other. Full article
(This article belongs to the Special Issue Carbon Nanohybrids for Biomedical Applications)
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Article
High Surface Area Nanoporous Activated Carbons Materials from Areca catechu Nut with Excellent Iodine and Methylene Blue Adsorption Cited by 1 | Viewed by 977
Abstract
Nanoporous carbon materials from biomass exhibit a high surface area due to well-defined pore structures. Therefore, they have been extensively used in separation and purification technologies as efficient adsorbents. Here, we report the iodine and methylene blue adsorption properties of the hierarchically porous [...] Read more.
Nanoporous carbon materials from biomass exhibit a high surface area due to well-defined pore structures. Therefore, they have been extensively used in separation and purification technologies as efficient adsorbents. Here, we report the iodine and methylene blue adsorption properties of the hierarchically porous carbon materials prepared from Areca catechu nut. The preparation method involves the phosphoric acid (H3PO4) activation of the Areca catechu nut powder. The effects of carbonization conditions (mixing ratio with H3PO4, carbonization time, and carbonization temperature) on the textural properties and surface functional groups were studied. The optimum textural properties were obtained at a mixing ratio of 1:1, carbonized for 3 h at 400 °C, and the sample achieved a high specific surface area of 2132.1 m2 g−1 and a large pore volume of 3.426 cm3 g−1, respectively. The prepared materials have amorphous carbon structures and contain oxygenated surface functional groups. Due to the well-defined micro-and mesopore structures with the high surface area and large pore volume, the optimal sample showed excellent iodine and methylene blue adsorption. The iodine number and methylene blue values were ca. 888 mg g−1 and 369 mg g−1, respectively. The batch adsorption studies of methylene dye were affected by pH, adsorbent dose, contact time, and initial concentration. The optimum parameters for the methylene blue adsorption were in alkaline pH, adsorbent dose of 2.8 g L−1, and contact time of 180 min. Equilibrium data could be best represented by the Langmuir isotherm model with a monolayer adsorption capacity of 333.3 mg g−1. Thus, our results demonstrate that the Areca catechu nut has considerable potential as the novel precursor material for the scalable production of high surface area hierarchically porous carbon materials that are essential in removing organic dyes from water. Full article
(This article belongs to the Collection Feature Papers in the Science and Engineering of Carbons)
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Article
Increased Electrical Conductivity of Carbon Nanotube Fibers by Thermal and Voltage Annealing Cited by 1 | Viewed by 1341
Abstract
We report the effect of annealing, both electrical and by applied voltage, on the electrical conductivity of fibers spun from carbon nanotubes (CNTs). Commercial CNT fibers were used as part of a larger goal to better understand the factors that go into making [...] Read more.
We report the effect of annealing, both electrical and by applied voltage, on the electrical conductivity of fibers spun from carbon nanotubes (CNTs). Commercial CNT fibers were used as part of a larger goal to better understand the factors that go into making a better electrical conductor from CNT fibers. A study of thermal annealing in a vacuum up to 800 °C was performed on smaller fiber sections along with a separate analysis of voltage annealing up to 7 VDC; both exhibited a sweet spot in the process as determined by a combination of a two-point probe measurement with a nanoprobe, resonant Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). Scaled-up tests were then performed in order to translate these results into bulk samples inside a tube furnace, with similar results that indicate the potential for an optimized method of achieving a better conductor sample made from CNT fibers. The results also help to determine the surface effects that need to be overcome in order to achieve this. Full article
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