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C, Volume 9, Issue 1 (March 2023) – 36 articles

Cover Story (view full-size image): The releasing performance of hybrid hydrogels composed of sodium alginate and graphene oxide was found to be affected by the crosslinking method. Two synthetic approaches were used: the Ca2+-induced gelation (physical hydrogel) and the radical co-polymerization (chemical hydrogel) in the presence of acrylate monomers. Using Curcumin as a model drug, the releasing performances were evaluated, highlighting that the release is a complex phenomenon involving carrier-to-drug interactions, swelling degree, and polarization processes, which can be modulated by an external voltage (chemical hydrogel). Taken together, the results proved that different synthetic approaches allowed the obtainment of materials with different performances, which can be useful to match different therapeutic needs. View this paper
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15 pages, 2833 KiB  
Article
Nanocomposites Produced with the Addition of Carbon Nanotubes Dispersed on the Surface of Cement Particles Using Different Non-Aqueous Media
by Vanessa Vilela Rocha, Bruno Athaíde Bacelar, Isabela Domingues Coelho and Péter Ludvig
C 2023, 9(1), 36; https://doi.org/10.3390/c9010036 - 22 Mar 2023
Viewed by 1449
Abstract
The inclusion of carbon nanotubes (CNTs) in cementitious composites has been studied due to their electrical, thermal, and mechanical enhancing properties. Considering the hydrophobic characteristics of CNTs, these nanomaterials need to be well dispersed in the aqueous media in which they are inserted [...] Read more.
The inclusion of carbon nanotubes (CNTs) in cementitious composites has been studied due to their electrical, thermal, and mechanical enhancing properties. Considering the hydrophobic characteristics of CNTs, these nanomaterials need to be well dispersed in the aqueous media in which they are inserted to guarantee those gains. Among the methods applied to produce such composites is the dispersion of CNTs on the surface of anhydrous cement particles using non-aqueous suspensions such as acetone, ethanol, or isopropanol. Even though those non-aqueous media have been individually studied by researchers, comparisons of the efficiency of CNTs dispersion was not found in the literature. Therefore, as a novelty, the present article aims to analyze the influence of the addition of the multi-walled CNTs dispersed in the cited three types of non-aqueous suspensions on the cement paste’s electrical and mechanical properties. Pastes containing 0%, 0.5%, and 1.0% of CNTs were prepared on the surface of anhydrous cement particles using a pre-dispersion technique based on simultaneous sonication and mechanical agitation in the three cited media. Tests to determine electric-volumetric resistivity, compressive strength, and splitting tensile strength were performed. It was observed that acetone dispersion decreases the cement paste’s electrical resistivity, even without the addition of CNTs. The cementitious composites with CNTs demonstrated increased mechanical strength (both compressive and tensile) using all three dispersion media. Statistical analysis (analysis of variance—ANOVA—and Tukey’s Test) was performed to evaluate the significance of the results. Full article
(This article belongs to the Collection Novel Applications of Carbon Nanotube-Based Materials)
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26 pages, 6774 KiB  
Review
Optimization and Process Effect for Microalgae Carbon Dioxide Fixation Technology Applications Based on Carbon Capture: A Comprehensive Review
by Gang Li, Wenbo Xiao, Tenglun Yang and Tao Lyu
C 2023, 9(1), 35; https://doi.org/10.3390/c9010035 - 16 Mar 2023
Cited by 13 | Viewed by 7493
Abstract
Microalgae carbon dioxide (CO2) fixation technology is among the effective ways of environmental protection and resource utilization, which can be combined with treatment of wastewater and flue gas, preparation of biofuels and other technologies, with high economic benefits. However, in industrial [...] Read more.
Microalgae carbon dioxide (CO2) fixation technology is among the effective ways of environmental protection and resource utilization, which can be combined with treatment of wastewater and flue gas, preparation of biofuels and other technologies, with high economic benefits. However, in industrial application, microalgae still have problems such as poor photosynthetic efficiency, high input cost and large capital investment. The technology of microalgae energy development and resource utilization needs to be further studied. Therefore, this work reviewed the mechanism of CO2 fixation in microalgae. Improving the carbon sequestration capacity of microalgae by adjusting the parameters of their growth conditions (e.g., light, temperature, pH, nutrient elements, and CO2 concentration) was briefly discussed. The strategies of random mutagenesis, adaptive laboratory evolution and genetic engineering were evaluated to screen microalgae with a high growth rate, strong tolerance, high CO2 fixation efficiency and biomass. In addition, in order to better realize the industrialization of microalgae CO2 fixation technology, the feasibility of combining flue gas and wastewater treatment and utilizing high-value-added products was analyzed. Considering the current challenges of microalgae CO2 fixation technology, the application of microalgae CO2 fixation technology in the above aspects is expected to establish a more optimized mechanism of microalgae carbon sequestration in the future. At the same time, it provides a solid foundation and a favorable basis for fully implementing sustainable development, steadily promoting the carbon peak and carbon neutrality, and realizing clean, green, low-carbon and efficient utilization of energy. Full article
(This article belongs to the Section Carbon Cycle, Capture and Storage)
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14 pages, 737 KiB  
Article
Agro-Industrial Waste Biochar Abated Nitrogen Leaching from Tropical Sandy Soils and Boosted Dry Matter Accumulation in Maize
by Michael Egyir, Innocent Yao Dotse Lawson, Daniel Etsey Dodor and Deogratius Luyima
C 2023, 9(1), 34; https://doi.org/10.3390/c9010034 - 14 Mar 2023
Cited by 1 | Viewed by 1681
Abstract
This study was conducted to assess the effects of amending tropical sandy soils with biochar derived from agro-industrial wastes on the leaching and utilization of nitrogen (N) by maize. The experiment was conducted in pots in a greenhouse with two sandy soil types [...] Read more.
This study was conducted to assess the effects of amending tropical sandy soils with biochar derived from agro-industrial wastes on the leaching and utilization of nitrogen (N) by maize. The experiment was conducted in pots in a greenhouse with two sandy soil types and two different biochars. The biochars used in this experiment were preselected in a preliminary column experiment that assessed the N retention capacities of the different biochars and those that exhibited the best retention capacities chosen for experimentation. The biochars evaluated included saw dust, rice husk and corncob pyrolyzed at 500 °C and the results from the column leaching experiment showed that sawdust biochar had superior retention capacities for both NO3 and NH4+, followed by rice husk biochar. The pot experiment utilized sawdust and rice husk biochars applied at rates of 0, 20 and 40 t/ha to the soil treated with different N sources including cow dung and ammonium sulfate and growing maize on the amendments for two seasons with each season lasting for five weeks. The soils were leached on the 14th and 28th days after planting to determine the amount of leachable N. Biochar amendments reduced the leaching of NO3N and NH4+N with no significant differences observed between biochar types, but between soil types. The abatement of leaching by biochar amendments consequently enhanced N uptake by maize and dry matter production and thus, agro-industrial waste biochar amendment is recommended for reducing leaching in tropical sandy soils. Full article
(This article belongs to the Special Issue Biomass—a Renewable Resource for Carbon Materials (2nd Edition))
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11 pages, 2536 KiB  
Article
Assessment of Fibrinogen Thermal Conductivity and Interaction Energy with Polyarylethersulfone (PAES) Clinical Hemodialysis Membranes at Normal and Elevated Patient Body Temperatures
by Arash Mollahosseini and Amira Abdelrasoul
C 2023, 9(1), 33; https://doi.org/10.3390/c9010033 - 12 Mar 2023
Cited by 1 | Viewed by 1358
Abstract
Fibrinogen (FB) can trigger several biological reactions and is one of the critical proteins targeted during hemodialysis (HD). A better understanding of the thermal behavior of FB and its interactions with polymeric membranes during the HD process is needed in both normal and [...] Read more.
Fibrinogen (FB) can trigger several biological reactions and is one of the critical proteins targeted during hemodialysis (HD). A better understanding of the thermal behavior of FB and its interactions with polymeric membranes during the HD process is needed in both normal and fever temperature conditions. This study calculated the thermal behavior of FB along with its interaction energy with polyarylethersulfone (PAES) clinical HD membranes using molecular dynamics (MD) approaches. The Dreiding force field was used for the MD simulations. The influence of temperature on the thermal conductivity (TC) and the interaction energy of the FB structure was assessed to understand the activation trends in fever conditions. Based on the MD simulation, the TC of FB at normal body temperature was 0.044 and 0.084 W/m·K according to equilibrium and non-equilibrium approaches, respectively. The elevation of temperature from normal to fever conditions increased the thermal conduction of FB to 0.577 and 0.114 W/m·K for equilibrium and non-equilibrium approaches, respectively. In addition, the elevation of patient blood temperature resulted in nearly 32 kcal/mol higher total interaction energy between FB and the PAES model. When end-stage renal disease (ESRD) patients have a HD session and experience fever and elevated temperature as a side effect, the interaction between FB and the membrane increases. More importantly, FB is exposed to more heat passage and accordingly more temperature-induced confirmation and activation compared to other human serum proteins such as albumin. Full article
(This article belongs to the Section Carbon Skeleton)
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24 pages, 3608 KiB  
Article
Efficient Removal of Tannic Acid from Olive Mill Wastewater Using Carbon Steel Slag
by Otmane Sarti, Fouad El Mansouri, El Habib Yahia, Emilia Otal, José Morillo and Mohamed Saidi
C 2023, 9(1), 32; https://doi.org/10.3390/c9010032 - 12 Mar 2023
Cited by 1 | Viewed by 1996
Abstract
Mediterranean countries experience a large production of olive oil, thus generating huge quantities of non-biodegradable vegetation waters. The discharge of these effluents into aquatic environments seriously affects the quality of surface waters. This study investigated the potential use of carbon steel slag (SS) [...] Read more.
Mediterranean countries experience a large production of olive oil, thus generating huge quantities of non-biodegradable vegetation waters. The discharge of these effluents into aquatic environments seriously affects the quality of surface waters. This study investigated the potential use of carbon steel slag (SS) as an adsorbent and improver for reducing olive mill wastewater (OMWW) toxicity. The elemental and structural characterization of SS was carried out using inductively coupled plasma-optical emission spectrometry (ICP/EOS), X-ray fluorescence (XRF), X-ray powder diffraction (XRD), scanning electron microscopy (SEM), and Brunauer–Emmett–Teller (BET) analysis. OMWW characterization indicated that the effluent was acidic in nature, with a pH of 4.8, a higher conductivity reaching 14.92 mS/cm, higher COD of 157.31 g/L, rich in organic matter 112.33 g/L, and total phenolic compounds of 11.13 g/L. The neutralization capacity of SS was demonstrated by reducing the OMWW’s acidic character. Afterward, the adsorption of tannic acid (TA) was investigated using SS. Parameters such as contact time, initial TA concentration, adsorbent dosage, pH, and temperature were investigated. The kinetic study indicated that the adsorption of TA onto SS fitted well with the second pseudo-order (r = 0.99) and Elovich (r = 0.98) models, indicating that the adsorption of TA was mainly chemical and depends on the reactions of oxide hydrolysis and hydroxides dissolution. Moreover, Langmuir isotherm has greatly described the adsorption of TA on SS (R = 0.997), suggesting that the surface of SS is homogenous, and the adsorption occurs mainly in monolayer. The maximum adsorption capacity reached 714.28 mg/g, indicating the higher capacity of SS to reduce the polyphenolic compounds in OMWW. This study demonstrated that SS residue from the steelmaking industry could present a highly interesting material for OMWW remediation. Full article
(This article belongs to the Special Issue Biomass—a Renewable Resource for Carbon Materials (2nd Edition))
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29 pages, 12143 KiB  
Review
Graphene-like Carbon Structure Synthesis from Biomass Pyrolysis: A Critical Review on Feedstock–Process–Properties Relationship
by Farhan Chowdhury Asif and Gobinda C. Saha
C 2023, 9(1), 31; https://doi.org/10.3390/c9010031 - 11 Mar 2023
Cited by 8 | Viewed by 5821
Abstract
Biomass pyrolysis is a promising route for synthesizing graphene-like carbon (GLC) structures, potentially offering a cost-effective and renewable alternative to graphene. This review paper responds to the call for highlighting the state of the art in GLC materials design and synthesis from renewable [...] Read more.
Biomass pyrolysis is a promising route for synthesizing graphene-like carbon (GLC) structures, potentially offering a cost-effective and renewable alternative to graphene. This review paper responds to the call for highlighting the state of the art in GLC materials design and synthesis from renewable biomass microwave pyrolysis. This paper includes an introduction of the microwave pyrolysis technology, information on feedstock variability and selection, discussion on the correlation between microwave pyrolysis process conditions and pyrolyzed product characteristics, and, more importantly, a section identifying any differences between pyrolyzing feedstock using the microwave pyrolysis method vs. conventional pyrolysis method. Furthermore, this work concludes by detailing the knowledge currently missing with the recommendation for future research/innovation directions. Full article
(This article belongs to the Special Issue Biomass—a Renewable Resource for Carbon Materials (2nd Edition))
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23 pages, 1243 KiB  
Review
Emerging Bio-Based Polymers from Lab to Market: Current Strategies, Market Dynamics and Research Trends
by Tomy Muringayil Joseph, Aparna Beena Unni, K. S. Joshy, Debarshi Kar Mahapatra, Józef Haponiuk and Sabu Thomas
C 2023, 9(1), 30; https://doi.org/10.3390/c9010030 - 07 Mar 2023
Cited by 11 | Viewed by 6023
Abstract
Due to the rising worldwide demand for green chemicals, the bio-based polymer market is anticipated to expand substantially in the future. The synthesis of functional polymers has been a burgeoning area of research for decades. The primary driving force behind the development of [...] Read more.
Due to the rising worldwide demand for green chemicals, the bio-based polymer market is anticipated to expand substantially in the future. The synthesis of functional polymers has been a burgeoning area of research for decades. The primary driving force behind the development of bio-based polymers has been their compostability and biodegradability, which are critical given the public concern about waste. Significant advancements in the method for refining biomass raw materials towards the creation of bio-based construction materials and products are driving this rise. Bio-based polymers with this chemical structure are more flexible and adaptive, which allows them to attain their intended characteristics and functionalities. In commercial applications and healthcare and biotechnology, where completely manufactured, naturally occurring biomolecules are utilized and such polymers have the greatest impact. At the same time, limitations in polymer architectural control, biostability, and structural dynamics hinder the creation of biocompatible and functionally varied polymers. From this standpoint, the importance of functional biosynthetic polymers in the future years is highlighted, as well as new methods for addressing the aforementioned challenges. The article comprehensively highlighted the current strategies, market dynamics, and research trends of emerging Bio-Based Polymers. In addition, the most recent scientific breakthroughs in bio-based polymers are discussed. Full article
(This article belongs to the Special Issue Biomass—a Renewable Resource for Carbon Materials (2nd Edition))
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21 pages, 5381 KiB  
Review
Graphene Nanocomposites in Space Sector—Fundamentals and Advancements
by Ayesha Kausar, Ishaq Ahmad, M. H. Eisa and Malik Maaza
C 2023, 9(1), 29; https://doi.org/10.3390/c9010029 - 03 Mar 2023
Cited by 7 | Viewed by 4254
Abstract
Graphene is one of the most significant carbon nanomaterials, with a one-atom-thick two-dimensional nanostructure. Like other nanocarbons, graphene has been used as a polymer reinforcement. This review explores the impact of graphene and graphene-based nanocomposites on aerospace applications. The fabrication and indispensable features [...] Read more.
Graphene is one of the most significant carbon nanomaterials, with a one-atom-thick two-dimensional nanostructure. Like other nanocarbons, graphene has been used as a polymer reinforcement. This review explores the impact of graphene and graphene-based nanocomposites on aerospace applications. The fabrication and indispensable features of graphene-derived nanocomposites have been considered. Numerous polymers and nanocomposites have been employed for aerospace systems such as reinforced thermosetting/thermoplastic polymers and epoxy/graphene nanocomposites. Moreover, graphene-modified carbon-fiber-based composites have been discussed for the space sector. Aerospace nanocomposites with graphene have been investigated for superior processability, structural features, morphology, heat stability, mechanical properties, flame resistance, electrical/thermal conductivity, radiation protection, and adhesion applications. Subsequently, epoxy and graphene-derived nanocomposites have been explored for heat/mechanically stable aerospace engineering structures, radiation-shielding materials, adhesives, coatings, etc. Full article
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17 pages, 8495 KiB  
Article
Obtention and Characterization of GO/Epoxy and GO-GPTMS/Epoxy Nanocompounds with Different Oxidation Degrees and Ultrasound Methods
by Areli Marlen Salgado-Delgado, Elizabeth Grissel González-Mondragón, Ricardo Hernández-Pérez, René Salgado-Delgado, José Alfonso Santana-Camilo and Alfredo Olarte-Paredes
C 2023, 9(1), 28; https://doi.org/10.3390/c9010028 - 01 Mar 2023
Cited by 2 | Viewed by 2050
Abstract
This work reports the obtention of nanocompounds from epoxy resin (EP) with graphenes at three different oxidation degrees (GO1, GO2, and GO3), functionalized with 3-glycidyloxypropyl trimethoxysilane (GPTMS), and three different graphene concentrations (1%, 2%, and 3%). The aim is to improve GO compatibility [...] Read more.
This work reports the obtention of nanocompounds from epoxy resin (EP) with graphenes at three different oxidation degrees (GO1, GO2, and GO3), functionalized with 3-glycidyloxypropyl trimethoxysilane (GPTMS), and three different graphene concentrations (1%, 2%, and 3%). The aim is to improve GO compatibility in EP and obtain a nanocompound with synergistic properties. Ultrasonic bath was used to disperse the GO, a factor in the effective interaction between GO and the polymeric matrix. The nanocompounds were characterized by FTIR, SEM, and mechanical tension testing. The FTIR analysis evidenced stretching bonds created during the functionalization of graphene oxide (GO) with the silane (GPTMS); they are characteristic Si-O-Si and Si-O-C at 1000 and 1085 cm−1, respectively. There was a difference between GO and GO-GPTMS nanocompounds regarding the formation of these signals. The SEM micrographs showed morphological changes when GO was added: the smooth fracture surface of EP became rougher. During tension testing, Young’s modulus (2.09 GPa) of GO2-GPTMS/epoxy nanocompounds (1% weight GO) increased by 35% while their resistance to traction (98.71 MPa) grew by 52%; both were higher than in pure EP. In conclusion, the variables studied (oxidation degrees and silanization) significantly affect the mechanical properties studied. Full article
(This article belongs to the Special Issue Advanced Carbon Based Nanomaterials)
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30 pages, 6860 KiB  
Article
On the Highly Ordered Graphene Structure of Non-Graphitic Carbons (NGCs)—A Wide-Angle Neutron Scattering (WANS) Study
by Oliver Osswald, Marc O. Loeh, Felix M. Badaczewski, Torben Pfaff, Henry E. Fischer, Alexandra Franz, Jens-Uwe Hoffmann, Manfred Reehuis, Peter J. Klar and Bernd M. Smarsly
C 2023, 9(1), 27; https://doi.org/10.3390/c9010027 - 27 Feb 2023
Cited by 4 | Viewed by 1863
Abstract
Non-graphitic carbons (NGCs), such as glass-like carbons, pitch cokes, and activated carbon consist of small graphene layer building stacks arranged in a turbostratic order. Both structure features, including the single graphene sheets as well as the stacks, possess structural disorder, which can be [...] Read more.
Non-graphitic carbons (NGCs), such as glass-like carbons, pitch cokes, and activated carbon consist of small graphene layer building stacks arranged in a turbostratic order. Both structure features, including the single graphene sheets as well as the stacks, possess structural disorder, which can be determined using wide-angle X-ray or neutron scattering (WAXS/WANS). Even if WANS data of NGCs have already been extensively reported and evaluated in different studies, there are still open questions with regard to their validation with WAXS, which is usually used for routine characterization. In particular, using WAXS for the damping of the atomic form factor and the limited measured range prevent the analysis of higher-ordered reflections, which are crucial for determining the stack/layer size (La, Lc) and disorder (σ1, σ3) based on the reflection widths. Therefore, in this study, powder WANS was performed on three types of carbon materials (glass-like carbon made out of a phenol-formaldehyde resin (PF-R), a mesophase pitch (MP), and a low softening-point pitch (LSPP)) using a beamline at ILL in Grenoble, providing a small wavelength and thus generating WANS data covering a large range of scattering vectors (0.052 Å−1 < s < 3.76 Å−1). Merging these WANS data with WANS data from previous studies, possessing high resolution in the small s range, on the same materials allowed us to determine both the interlayer and the interlayer structure as accurately as possible. As a main conclusion, we found that the structural disorder of the graphene layers themselves was significantly smaller than previously assumed. Full article
(This article belongs to the Special Issue Characterization of Disorder in Carbons (2nd Edition))
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15 pages, 3329 KiB  
Article
Manganese Oxide Loaded Carbon Fiber for Solar Energy Harvesting and Oil Decomposition
by Yong X. Gan, Anh B. Tran, Alexander Rivera, Ryan Wu, Natnichar Sukkoed, Zhen Yu, Jeremy B. Gan, Dominic Dominguez and Francisco J. Chaparro
C 2023, 9(1), 26; https://doi.org/10.3390/c9010026 - 26 Feb 2023
Viewed by 3172
Abstract
In this work, a manganese oxide electrode, containing carbon nanofiber composites (MnO2/CNF), has been made through electrospinning, oxidization, and partial carbonization high-temperature treatment. Scanning electron microscopy (SEM) was used to observe the morphology of the nanofiber and analyze the composition of [...] Read more.
In this work, a manganese oxide electrode, containing carbon nanofiber composites (MnO2/CNF), has been made through electrospinning, oxidization, and partial carbonization high-temperature treatment. Scanning electron microscopy (SEM) was used to observe the morphology of the nanofiber and analyze the composition of the fiber. The fiber size range and element distribution were determined. The oxide nanoparticles were modeled as electrorheological suspensions in the polyacrylonitrile polymer solution during electrospinning. The dielectrophoretic behavior of the particles subjected to non-uniform electric fields were analyzed and the motion of the oxide particles under the actions from fluctuating electric fields was investigated to explain the sporadic distribution of nanoparticles within the composite nanofibers. A photoactive anode was made from the composite nanofiber and the decomposition of spilled oil was performed under sunlight illumination. It was observed that the manganese oxide containing carbon nanofiber composite electrode can generate electricity and clean the spilled oil under sunlight. Both energy conversion and environment cleaning concepts were demonstrated. Full article
(This article belongs to the Special Issue Porous Carbon-Based Electrodes)
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13 pages, 5491 KiB  
Article
Highly Selective Detection of Hydrogen Sulfide by Simple Cu-CNTs Nanocomposites
by Nahida Musayeva, Hadiya Khalilova, Bakhtiyar Izzatov, Giovanna Trevisi, Shahla Ahmadova and Muhammad Alizada
C 2023, 9(1), 25; https://doi.org/10.3390/c9010025 - 24 Feb 2023
Cited by 3 | Viewed by 1499
Abstract
The presented work is devoted to the preparation of nanocomposites based on multiwall carbon nanotubes (MWCNTs) and copper (Cu) nanoparticles by a simple chemical method, and to study their sensing properties to hydrogen sulfide (H2S) gas. The Cu decorated multiwall carbon [...] Read more.
The presented work is devoted to the preparation of nanocomposites based on multiwall carbon nanotubes (MWCNTs) and copper (Cu) nanoparticles by a simple chemical method, and to study their sensing properties to hydrogen sulfide (H2S) gas. The Cu decorated multiwall carbon nanotubes (MWCNTs/Cu) were prepared by the deposition of very thin Cu layers on the pristine and functionalized multiwall carbon nanotubes (f-MWCNTs) using both physical (electron beam evaporation (EBE)) and chemical (electrochemical deposition) methods. MWCNTs/Cu prepared in the two above-mentioned ways, their sensing properties were studied, and the results were comparatively analyzed. The effect of the chemical functionalization of MWCNTs by oxygen-containing groups on the sensing properties of these f-MWCNT/Cu nanocomposites has been investigated. All the prepared sensors demonstrated high sensitivity and selectivity to H2S in the air at room temperature. The f-MWCNT/Cu structure obtained by the chemical method demonstrated about 5 times (~400%) higher sensitivity (∆R/R0) to H2S gas compared to the similar structure obtained by the physical method. The temperature effect on sensory characteristics (response and self-recovery time) of the f-MWCNTs/Cu structure was also studied. Full article
(This article belongs to the Collection Novel Applications of Carbon Nanotube-Based Materials)
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12 pages, 1556 KiB  
Article
Biomass-Derived N-Doped Activated Carbon from Eucalyptus Leaves as an Efficient Supercapacitor Electrode Material
by Dinesh Bejjanki, Praveen Banothu, Vijay Bhooshan Kumar and Puttapati Sampath Kumar
C 2023, 9(1), 24; https://doi.org/10.3390/c9010024 - 17 Feb 2023
Cited by 9 | Viewed by 2530
Abstract
Biomass-derived activated carbon is one of the promising electrode materials in supercapacitor applications. In this work bio-waste (oil extracted from eucalyptus leaves) was used as a carbon precursor to synthesize carbon material with ZnCl2 as a chemical activating agent and activated carbon [...] Read more.
Biomass-derived activated carbon is one of the promising electrode materials in supercapacitor applications. In this work bio-waste (oil extracted from eucalyptus leaves) was used as a carbon precursor to synthesize carbon material with ZnCl2 as a chemical activating agent and activated carbon was synthesized at various temperatures ranging from 400 to 800 °C. The activated carbon at 700 °C showed a surface area of 1027 m2 g−1 and a specific capacitance of 196 F g−1. In order to enhance the performance, activated carbon was doped with nitrogen-rich urea at a temperature of 700 °C. The obtained activated carbon and N-doped activated carbon was characterized by phase and crystal structural using (XRD and Raman), morphological using (SEM), and compositional analysis using (FTIR). The electrochemical measurements of carbon samples were evaluated using an electrochemical instrument and NAC-700 °C exhibited a specific capacitance of 258 F g−1 at a scan rate of 5 mV s−1 with a surface area of 1042 m2 g−1. Thus, surface area and functionalizing the groups with nitrogen showed better performance and it can be used as an electrode material for supercapacitor cell applications. Full article
(This article belongs to the Special Issue Biomass—a Renewable Resource for Carbon Materials)
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11 pages, 1450 KiB  
Article
Joule Heating of Carbon-Based Materials Obtained by Carbonization of Para-Aramid Fabrics
by Daniel Karthik, Jiri Militky, Yuanfeng Wang and Mohanapriya Venkataraman
C 2023, 9(1), 23; https://doi.org/10.3390/c9010023 - 15 Feb 2023
Cited by 1 | Viewed by 2262
Abstract
The Joule heating behavior of carbon-based materials obtained by the process of carbonization of industrial para-aramid fabric wastes are investigated in the present work. Carbonization involves a process of thermally decomposing organic material, thereby altering its physical and chemical properties to obtain carbon-rich [...] Read more.
The Joule heating behavior of carbon-based materials obtained by the process of carbonization of industrial para-aramid fabric wastes are investigated in the present work. Carbonization involves a process of thermally decomposing organic material, thereby altering its physical and chemical properties to obtain carbon-rich materials that are electrically conductive and display Joule heating behavior. The principle of Joule heating is based on the intrinsic electrical resistance of the material across an applied voltage. Here, para-aramid woven fabric wastes are converted into activated carbon materials through straightforward, controlled, single-step thermal treatments by three different kinds of atmosphere, i.e., in the CO2 evolved from charcoal, a mixture of gases from ammonium bicarbonate salt (NH4HCO3), and Nitrogen gas (N2), respectively, inside a high-temperature furnace. The carbonization temperatures were varied from 800 to 1100 °C. The carbonization process variables were optimized to obtain carbon-rich materials with lower electrical resistivity. The results of electrical resistivity measurements show that for all three methods, the electrical resistivity decreases with increasing carbonization temperatures. An experimental setup consisting of an infrared (IR) camera, positioned over the surface of the fabric specimen to record the surface temperature of the material connected to a DC power supply, was employed. The kinetics of Joule heating and subsequent cooling were also analyzed at a fixed voltage of 5 V by recording the changes in surface temperature with respect to time. The heating–cooling cycle is described by a simple kinetic model of first order. Full article
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26 pages, 7614 KiB  
Article
Valorization of Exhausted Olive Pomace for the Production of a Fuel for Direct Carbon Fuel Cell
by Najla Grioui, Amal Elleuch, Kamel Halouani and Yongdan Li
C 2023, 9(1), 22; https://doi.org/10.3390/c9010022 - 14 Feb 2023
Viewed by 1399
Abstract
In this study, exhausted olive pomace (EOP) biochar prepared by carbonization at 400 °C is investigated as a fuel in a direct carbon fuel cell (DCFC) with an electrolyte-supported configuration. The feasibility of using the EOP biochar in the DCFC is confirmed, showing [...] Read more.
In this study, exhausted olive pomace (EOP) biochar prepared by carbonization at 400 °C is investigated as a fuel in a direct carbon fuel cell (DCFC) with an electrolyte-supported configuration. The feasibility of using the EOP biochar in the DCFC is confirmed, showing a maximum power density of 10 mW·cm−2 at 700 °C. This limited DCFC performance is compared with other biochars prepared under similar conditions and interrelated with various biochar physico-chemical characteristics, as well as their impact on the DCFC’s chemical and electrochemical reaction mechanisms. A high ash content (21.55%) and a low volatile matter (40.62%) content of the EOP biochar are among the main causes of the DCFC’s limited output. Silica is the major impurity in the EOP biochar ash, which explains the limited cell performance as it causes low reactivity and limited electrical conductivity because of its non-crystal structure. The relatively poor DCFC performance when fueled by the EOP biochar can be overcome by further pre- and post-treatment of this renewable fuel. Full article
(This article belongs to the Special Issue Biomass—a Renewable Resource for Carbon Materials)
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12 pages, 2450 KiB  
Article
Thermal Transport Study in a Strained Carbon Nanotube and Graphene Junction Using Phonon Wavepacket Analysis
by Jungkyu Park
C 2023, 9(1), 21; https://doi.org/10.3390/c9010021 - 11 Feb 2023
Viewed by 1318
Abstract
This study investigates single-mode phonon scattering from a junction structure consisting of a (6,6) single-walled carbon nanotube (SWCNT) and graphene, subject to mechanical deformation, using phonon wavepacket analysis. Results show that longitudinal acoustic (LA) and transverse acoustic (TA) phonons at low frequencies are [...] Read more.
This study investigates single-mode phonon scattering from a junction structure consisting of a (6,6) single-walled carbon nanotube (SWCNT) and graphene, subject to mechanical deformation, using phonon wavepacket analysis. Results show that longitudinal acoustic (LA) and transverse acoustic (TA) phonons at low frequencies are transmitted more effectively through the SWCNT–graphene junction when the junction is deformed. As low-frequency phonons in LA and TA modes are major energy carriers, it is expected that thermal transport across the SWCNT–graphene junction will be more efficient when the junction is deformed. Interfacial thermal resistance across the SWCNT-graphene junction was calculated using reverse nonequilibrium molecular dynamics (RNEMD). The RNEMD results show that the interfacial thermal resistance decreases when the structure is elongated, deforming the junction between the SWCNT and graphene. However, there was no notable difference in the transmission of twisting (TW) and flexural (FO) phonons when the junction was deformed. The study also showed that the transmission of phonon energy through the SWCNT–graphene junction has a slight dependence on the group velocity of phonons, with phonons having higher group velocities transmitting the junction more effectively. The findings of this research will play a significant role in advancing the development of futuristic electronics by providing a tool for developing 3D carbon nanostructures with high thermal performance under mechanical deformation. Full article
(This article belongs to the Special Issue Characterization of Disorder in Carbons (2nd Edition))
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17 pages, 4323 KiB  
Article
Doping of Graphene Nanostructure with Iron, Nickel and Zinc as Selective Detector for the Toxic Gas Removal: A Density Functional Theory Study
by Fatemeh Mollaamin and Majid Monajjemi
C 2023, 9(1), 20; https://doi.org/10.3390/c9010020 - 09 Feb 2023
Cited by 16 | Viewed by 2399
Abstract
In this research, the ability of transition metals (TM)-doped graphene nanosheets to adsorb the toxic gas CO has been investigated. The Langmuir adsorption model was used, with a three-layered ONIOM, using the CAM-B3LYP functional accompanying the LANL2DZ and 6-31+G (d,p) basis sets, and [...] Read more.
In this research, the ability of transition metals (TM)-doped graphene nanosheets to adsorb the toxic gas CO has been investigated. The Langmuir adsorption model was used, with a three-layered ONIOM, using the CAM-B3LYP functional accompanying the LANL2DZ and 6-31+G (d,p) basis sets, and using the Gaussian 16 revision C.01 program, on the complexes of CO adsorbed on (Fe, Ni, Zn)-doped graphene nanosheets. The order of the changes of charge density for the Langmuir adsorption of CO on Fe-doped, Ni-doped, and Zn-doped graphene nanosheets has been investigated. This shows the greatest change of charge density for the Ni-doped graphene nanosheet. However, based on NMR spectroscopy, sharp peaks around the Ni-doped area on the surface of the graphene nanosheet have been observed. In addition, the Ni-doped graphene nanosheet has a large effect on the bond orbitals of C-Ni in the adsorption of CO, having the maximum occupancy. The values of ΔGadso, calculated through IR, showed that ΔGads,CO Fe-doped GRo has the highest value, because of a charge density transfer from the oxygen atom in carbon monoxide to the Fe-doped graphene nanosheet. The frontier molecular orbitals, HOMO and LUMO, and the band energy gap accompanying some chemical reactivity parameters, have revealed the attributes of the molecular electrical transport of (Fe, Ni, Zn)-doped graphene nanosheets for the adsorption of CO. As a result, since a CO molecule interacts simultaneously with a Fe, Ni, or Zn atom and the C-C nanosheet, at first it might be separated, as in this state a CO atom constructs a physical bond with the Fe, Ni, or Zn atom, and then the other could be adsorbed chemically on the C-C nanosheet surface. Finally, our results have shown that a considerable amount of charge transfer occurs between CO molecules and TM-doped graphene nanosheets after adsorption, which suggests that TM-doped graphene is more sensitive and selective to the adsorption of CO than a pristine graphene surface. Full article
(This article belongs to the Special Issue Carbons for Health and Environmental Protection)
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30 pages, 8911 KiB  
Review
Carbon Fibers: From PAN to Asphaltene Precursors; A State-of-Art Review
by Hossein Bisheh and Yasmine Abdin
C 2023, 9(1), 19; https://doi.org/10.3390/c9010019 - 04 Feb 2023
Cited by 3 | Viewed by 6481
Abstract
Due to their outstanding material properties, carbon fibers are widely used in various industrial applications as functional or structural materials. This paper reviews the material properties and use of carbon fiber in various applications and industries and compares it with other existing fillers [...] Read more.
Due to their outstanding material properties, carbon fibers are widely used in various industrial applications as functional or structural materials. This paper reviews the material properties and use of carbon fiber in various applications and industries and compares it with other existing fillers and reinforcing fibers. The review also examines the processing of carbon fibers and the main challenges in their fabrication. At present, two main precursors are primarily utilized to produce carbon fibers, i.e., polyacrylonitrile (PAN) and petroleum pitch. Each of these precursors makes carbon fibers with different properties. However, due to the costly and energy-intensive processes of carbon fiber production based on the existing precursors, there is an increasingly growing need to introduce cheaper precursors to compete with other fibers on the market. A special focus will be given to the most recent development of manufacturing more sustainable and cost-effective carbon fibers derived from petroleum asphaltenes. This review paper demonstrates that low-cost asphaltene-based carbon fibers can be a substitute for costly PAN/pitch-based carbon fibers at least for functional applications. The value proposition, performance/cost advantages, potential market, and market size as well as processing challenges and methods for overcoming these will be discussed. Full article
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18 pages, 3322 KiB  
Article
Physical Processes Occurring in Dispersed Media with Carbon Nanomaterials under the Influence of Ultrasonification
by Svetlana Obukhova and Evgenii Korolev
C 2023, 9(1), 18; https://doi.org/10.3390/c9010018 - 31 Jan 2023
Viewed by 1456
Abstract
The up-to-date carbon nanoparticle application in materials science and composites is mostly represented by controlling of different methods of structure formation including incorporation of nanomaterials or nano-modifiers. The efficiency of such methods depends on disagglomeration and the distribution degree of the carbon nanoparticle [...] Read more.
The up-to-date carbon nanoparticle application in materials science and composites is mostly represented by controlling of different methods of structure formation including incorporation of nanomaterials or nano-modifiers. The efficiency of such methods depends on disagglomeration and the distribution degree of the carbon nanoparticle within a dispersion medium, which are critical parameters to produce a composite with improved performance. At the same time, common approaches such as a surface activation or using surfactants do not guarantee a homogeneous dispersion of carbon nanoparticles. This research reports on a theoretical analysis of physical processes which take place during the ultrasonic treatment which is a widely used method for dispersion of nanomaterials. The experimental data demonstrate an efficiency of the proposed method and prove the theoretical assumptions. The theoretical analysis performed in this study can be applied to implement and scale-up the process using sonicators. It was established that ultrasonic treatment has a more intensive effect in an organic hydrocarbon medium. So, in industrial oil, the heating rate from ultrasonification is 20 °C/min, in residual selective purification extract, it is 33 °C/min. For aqueous systems, the heating rate from ultrasonification is significantly lower and amounts to 2 °C /min for suspensions with Sulfanol and 11 °C/min for suspensions with ViscoCrete 2100. It was established that in the studied dispersed systems (aqueous solutions with surfactants and organic medium), there is no directly proportional dependence of the amount of heating of suspensions on the duration of ultrasound dispersion (USD), which is caused by ultrasonic dispersion not under adiabatic conditions, as well as the dependence of absorption coefficient of ultrasonic energy for dispersed systems on parameters of system structure. Full article
(This article belongs to the Collection Novel Applications of Carbon Nanotube-Based Materials)
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29 pages, 5682 KiB  
Review
Carbon Capture Materials in Post-Combustion: Adsorption and Absorption-Based Processes
by Abdulrahman Allangawi, Eman F. H. Alzaimoor, Haneen H. Shanaah, Hawraa A. Mohammed, Husain Saqer, Ahmed Abd El-Fattah and Ayman H. Kamel
C 2023, 9(1), 17; https://doi.org/10.3390/c9010017 - 29 Jan 2023
Cited by 8 | Viewed by 6145
Abstract
Global warming and climate changes are among the biggest modern-day environmental problems, the main factor causing these problems is the greenhouse gas effect. The increased concentration of carbon dioxide in the atmosphere resulted in capturing increased amounts of reflected sunlight, causing serious acute [...] Read more.
Global warming and climate changes are among the biggest modern-day environmental problems, the main factor causing these problems is the greenhouse gas effect. The increased concentration of carbon dioxide in the atmosphere resulted in capturing increased amounts of reflected sunlight, causing serious acute and chronic environmental problems. The concentration of carbon dioxide in the atmosphere reached 421 ppm in 2022 as compared to 280 in the 1800s, this increase is attributed to the increased carbon dioxide emissions from the industrial revolution. The release of carbon dioxide into the atmosphere can be minimized by practicing carbon capture utilization and storage methods. Carbon capture utilization and storage (CCUS) has four major methods, namely, pre-combustion, post-combustion, oxyfuel combustion, and direct air capture. It has been reported that applying CCUS can capture up to 95% of the produced carbon dioxide in running power plants. However, a reported cost penalty and efficiency decrease hinder the wide applicability of CCUS. Advancements in the CCSU were made in increasing the efficiency and decreasing the cost of the sorbents. In this review, we highlight the recent developments in utilizing both physical and chemical sorbents to capture carbon. This includes amine-based sorbents, blended absorbents, ionic liquids, metal-organic framework (MOF) adsorbents, zeolites, mesoporous silica materials, alkali-metal adsorbents, carbonaceous materials, and metal oxide/metal oxide-based materials. In addition, a comparison between recently proposed kinetic and thermodynamic models was also introduced. It was concluded from the published studies that amine-based sorbents are considered assuperior carbon-capturing materials, which is attributed to their high stability, multifunctionality, rapid capture, and ability to achieve large sorption capacities. However, more work must be done to reduce their cost as it can be regarded as their main drawback. Full article
(This article belongs to the Section Carbon Cycle, Capture and Storage)
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20 pages, 3025 KiB  
Article
Hands-On Quantum Sensing with NV Centers in Diamonds
by J. L. Sánchez Toural, V. Marzoa, R. Bernardo-Gavito, J. L. Pau and D. Granados
C 2023, 9(1), 16; https://doi.org/10.3390/c9010016 - 29 Jan 2023
Viewed by 4585
Abstract
The physical properties of diamond crystals, such as color or electrical conductivity, can be controlled via impurities. In particular, when doped with nitrogen, optically active nitrogen-vacancy centers (NV), can be induced. The center is an outstanding quantum spin system that [...] Read more.
The physical properties of diamond crystals, such as color or electrical conductivity, can be controlled via impurities. In particular, when doped with nitrogen, optically active nitrogen-vacancy centers (NV), can be induced. The center is an outstanding quantum spin system that enables, under ambient conditions, optical initialization, readout, and coherent microwave control with applications in sensing and quantum information. Under optical and radio frequency excitation, the Zeeman splitting of the degenerate states allows the quantitative measurement of external magnetic fields with high sensitivity. This study provides a pedagogical introduction to the properties of the NV centers as well as a step-by-step process to develop and test a simple magnetic quantum sensor based on color centers with significant potential for the development of highly compact multisensor systems. Full article
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12 pages, 5369 KiB  
Article
Galling-Free Fine Blanking of Titanium Plates Using Carbon-Supersaturated High-Speed Steel Punch
by Tatsuhiko Aizawa and Kenji Fuchiwaki
C 2023, 9(1), 15; https://doi.org/10.3390/c9010015 - 25 Jan 2023
Cited by 4 | Viewed by 1560
Abstract
A carbon-supersaturated (CS-) high-speed steel punch was prepared using low-temperature plasma carburizing for fine blanking of pure titanium plates. The bare high-speed steel punch was also prepared as a reference to describe the adhesion and abrasive galling in the fine blanking of the [...] Read more.
A carbon-supersaturated (CS-) high-speed steel punch was prepared using low-temperature plasma carburizing for fine blanking of pure titanium plates. The bare high-speed steel punch was also prepared as a reference to describe the adhesion and abrasive galling in the fine blanking of the titanium plates, even in a single shot. The CS-punch was free from severe chemical galling, even after repeatedly fine-blanking the pure titanium plates. A microstructure analysis, element mapping and a chemical composition analysis demonstrated that titanium debris fragments slightly deposited at the CS-punch edges in the presence of agglomerated free-carbon film due to the CS-punch. This galling-free fine-blanking behavior came from the in situ formation of free carbon tribofilms. This in situ lubrication resulted in the completely burnished surfaces of pure titanium blanks. Full article
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3 pages, 260 KiB  
Editorial
Acknowledgment to the Reviewers of C-Journal of Carbon Research in 2022
by C-Journal of Carbon Research Editorial Office
C 2023, 9(1), 14; https://doi.org/10.3390/c9010014 - 20 Jan 2023
Viewed by 917
Abstract
High-quality academic publishing is built on rigorous peer review [...] Full article
20 pages, 5171 KiB  
Review
Avant-Garde Polymer and Nano-Graphite-Derived Nanocomposites—Versatility and Implications
by Ayesha Kausar
C 2023, 9(1), 13; https://doi.org/10.3390/c9010013 - 19 Jan 2023
Cited by 4 | Viewed by 1969
Abstract
Graphite (stacked graphene layers) has been modified in several ways to enhance its potential properties/utilities. One approach is to convert graphite into a unique ‘nano-graphite’ form. Nano-graphite consists of few-layered graphene, multi-layered graphene, graphite nanoplatelets, and other graphene aggregates. Graphite can be converted [...] Read more.
Graphite (stacked graphene layers) has been modified in several ways to enhance its potential properties/utilities. One approach is to convert graphite into a unique ‘nano-graphite’ form. Nano-graphite consists of few-layered graphene, multi-layered graphene, graphite nanoplatelets, and other graphene aggregates. Graphite can be converted to nano-graphite using physical and chemical methods. Nano-graphite, similar to graphite, has been reinforced in conducting polymers/thermoplastics/rubbery matrices to develop high-performance nanocomposites. Nano-graphite and polymer/nano-graphite nanomaterials have characteristics that are advantageous over those of pristine graphitic materials. This review basically highlights the essential features, design versatilities, and applications of polymer/nano-graphite nanocomposites in solar cells, electromagnetic shielding, and electronic devices. Full article
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13 pages, 3278 KiB  
Article
Novel Nanobiocatalyst Constituted by Lipase from Burkholderia cepacia Immobilized on Graphene Oxide Derived from Grape Seed Biochar
by Lays C. de Almeida, Erikles L. O. Andrade, Jefferson C. B. Santos, Roberta M. Santos, Alini T. Fricks, Lisiane dos S. Freitas, Álvaro S. Lima, Matheus M. Pereira and Cleide M. F. Soares
C 2023, 9(1), 12; https://doi.org/10.3390/c9010012 - 19 Jan 2023
Cited by 2 | Viewed by 1857
Abstract
The present research aims to study the process of immobilization of lipase from Burkholderia cepacia by physical adsorption on graphene oxide derived (GO) from grape seed biochar. Additionally, the modified Hummers method was used to obtain the graphene oxide. Moreover, Fourier transform infrared [...] Read more.
The present research aims to study the process of immobilization of lipase from Burkholderia cepacia by physical adsorption on graphene oxide derived (GO) from grape seed biochar. Additionally, the modified Hummers method was used to obtain the graphene oxide. Moreover, Fourier transform infrared spectroscopy, Raman spectrum, X-ray diffraction, and point of zero charge were used for the characterization of the GO. The influences of pH, temperature, enzyme/support concentration on the catalytic activity were evaluated for the immobilized biocatalyst. The best immobilization was found (543 ± 5 U/g of support) in the pH 4.0. Considering the biochemical properties, the optimal pH and temperature were 3.0 and 50 °C, respectively, for the immobilized biocatalyst. Reusability studies exhibited that the immobilized lipase well kept 60% of its original activity after 5 cycles of reuse. Overall, these results showed the high potential of graphene oxide obtained from biochar in immobilization lipase, especially the application of nanobiocatalysts on an industrial scale. Full article
(This article belongs to the Special Issue Carbon-Based Catalyst (2nd Edition))
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15 pages, 6577 KiB  
Article
Novel Ultrahard Extended Hexagonal C10, C14 and C18 Allotropes with Mixed sp2/sp3 Hybridizations: Crystal Chemistry and Ab Initio Investigations
by Samir F. Matar, Volker Eyert and Vladimir L. Solozhenko
C 2023, 9(1), 11; https://doi.org/10.3390/c9010011 - 18 Jan 2023
Cited by 3 | Viewed by 1555
Abstract
Based on 4H, 6H and 8H diamond polytypes, novel extended lattice allotropes C10, C14 and C18 characterized by mixed sp3/sp2 carbon hybridizations were devised based on crystal chemistry rationale and first-principles calculations of the ground state [...] Read more.
Based on 4H, 6H and 8H diamond polytypes, novel extended lattice allotropes C10, C14 and C18 characterized by mixed sp3/sp2 carbon hybridizations were devised based on crystal chemistry rationale and first-principles calculations of the ground state structures and energy derived properties: mechanical, dynamic (phonons), and electronic band structure. The novel allotropes were found increasingly cohesive along the series, with cohesive energy values approaching those of diamond polytypes. Regarding mechanical properties, C10, C14, and C18 were found ultrahard with Vickers hardness slightly below that of diamond. All of them are dynamically stable, with positive phonon frequencies reaching maxima higher than in diamond due to the stretching modes of C=C=C linear units. The electronic band structures expectedly reveal the insulating character of all three diamond polytypes and the conductive character of the hybrid allotropes. From the analysis of the bands crossing the Fermi level, a nesting Fermi surface was identified, allowing us to predict potential superconductive properties. Full article
(This article belongs to the Section Carbon Materials and Carbon Allotropes)
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11 pages, 2485 KiB  
Article
Removal of Arsenic(III) from Water with a Combination of Graphene Oxide (GO) and Granular Ferric Hydroxide (GFH) at the Optimum Molecular Ratio
by Athanasia K. Tolkou, Elena Cristina Rada, Vincenzo Torretta, Maria Xanthopoulou, George Z. Kyzas and Ioannis A. Katsoyiannis
C 2023, 9(1), 10; https://doi.org/10.3390/c9010010 - 15 Jan 2023
Cited by 3 | Viewed by 2002
Abstract
The occurrence of arsenic in water is a global problem for public health. Several removal technologies have been developed for arsenic removal from water, and adsorption onto iron oxy-hydroxides is the most widely used technique. Granular ferric hydroxide (GFH) has been used mainly [...] Read more.
The occurrence of arsenic in water is a global problem for public health. Several removal technologies have been developed for arsenic removal from water, and adsorption onto iron oxy-hydroxides is the most widely used technique. Granular ferric hydroxide (GFH) has been used mainly for As(V) removal, but it has the disadvantage that it can create a problem with the residual concentration of iron in the water. Moreover, graphene oxide (GO), which contains a large amount of reactive oxygen, exhibits high adsorbing capacity. In this study, the combined use of GO and GFH as adsorbent materials in different molar ratios was investigated in order to achieve the maximum As(III) removal from aqueous solutions. The effect of the adsorbent’s dosage, pH value, contact time, initial As(III), and different molar ratios of GO/GFH was examined. As depicted, the presence of GFH enhances the use of GO. In particular, the molar ratio of GO/GFH 2:1 (i.e., 0.2 g/L GO and 0.1 g/L GFH) is chosen as optimal at pH value 7.0 ± 0.1, while the removal percentage increased from 10 % (absence of GFH) to 90% with the simultaneous addition of GFH. Freundlich isotherm and pseudo-second-order kinetic models described the experimental data adequately and the highest adsorption capacity that was achieved was 22.62 μg/g. Full article
(This article belongs to the Special Issue Adsorption on Carbon-Based Materials)
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13 pages, 8865 KiB  
Article
3D Variable Range Hopping Electrical Conduction of a Carbon from Polyaniline Vapor
by Hiromasa Goto
C 2023, 9(1), 9; https://doi.org/10.3390/c9010009 - 12 Jan 2023
Cited by 1 | Viewed by 1549
Abstract
Carbon with a metallic reflection was prepared from polyaniline (PANI) vapor deposited on the inner quartz wall of a furnace. Electron probe microanalyzer analysis proved that the resultant contained carbon, oxygen, nitrogen, and sulfur atoms. A Dysonian line shape with paramagnetic properties was [...] Read more.
Carbon with a metallic reflection was prepared from polyaniline (PANI) vapor deposited on the inner quartz wall of a furnace. Electron probe microanalyzer analysis proved that the resultant contained carbon, oxygen, nitrogen, and sulfur atoms. A Dysonian line shape with paramagnetic properties was observed for the resulting carbon from PANI in the electron spin-resonance spectroscopy measurement. The resistance vs. temperature curve of the carbon indicated semiconductor-insulator properties in a low-temperature range. Electrical conduction in the carbon was carried out with 3D variable range hopping. Full article
(This article belongs to the Special Issue Characterization of Disorder in Carbons (2nd Edition))
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17 pages, 3676 KiB  
Article
Release of Bioactive Molecules from Graphene Oxide-Alginate Hybrid Hydrogels: Effect of Crosslinking Method
by Lorenzo Francesco Madeo, Manuela Curcio, Francesca Iemma, Fiore Pasquale Nicoletta, Silke Hampel and Giuseppe Cirillo
C 2023, 9(1), 8; https://doi.org/10.3390/c9010008 - 08 Jan 2023
Cited by 2 | Viewed by 1776
Abstract
To investigate the influence of crosslinking methods on the releasing performance of hybrid hydrogels, we synthesized two systems consisting of Graphene oxide (GO) as a functional element and alginate as polymer counterpart by means of ionic gelation (physical method, [...] Read more.
To investigate the influence of crosslinking methods on the releasing performance of hybrid hydrogels, we synthesized two systems consisting of Graphene oxide (GO) as a functional element and alginate as polymer counterpart by means of ionic gelation (physical method, HAGOP) and radical polymerization (chemical method, HAGOC). Formulations were optimized to maximize the GO content (2.0 and 1.15% for HAGOP and HAGOC, respectively) and Curcumin (CUR) was loaded as a model drug at 2.5, 5.0, and 7.5% (by weight). The physico-chemical characterization confirmed the homogeneous incorporation of GO within the polymer network and the enhanced thermal stability of hybrid vs. blank hydrogels. The determination of swelling profiles showed a higher swelling degree for HAGOC and a marked pH responsivity due to the COOH functionalities. Moreover, the application of external voltages modified the water affinity of HAGOC, while they accelerated the degradation of HAGOP due to the disruption of the crosslinking points and the partial dissolution of alginate. The evaluation of release profiles, extensively analysed by the application of semi-empirical mathematical models, showed a sustained release from hybrid hydrogels, and the possibility to modulate the releasing amount and rate by electro-stimulation of HAGOC. Full article
(This article belongs to the Special Issue Carbon Nanohybrids for Biomedical Applications)
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26 pages, 5004 KiB  
Article
Comparison of the Electrochemical Response of Carbon-Fiber-Reinforced Plastic (CFRP), Glassy Carbon, and Highly Ordered Pyrolytic Graphite (HOPG) in Near-Neutral Aqueous Chloride Media
by Stanley Udochukwu Ofoegbu, Mário Guerreiro Silva Ferreira, Helena I. S. Nogueira and Mikhail Zheludkevich
C 2023, 9(1), 7; https://doi.org/10.3390/c9010007 - 07 Jan 2023
Cited by 1 | Viewed by 2685
Abstract
Carbon-fiber-reinforced polymers (CFRP), being conductive, are capable of supporting cathodic oxygen reduction reactions (ORR) and thus promote galvanic corrosion when coupled to many metallic materials. Hence, understanding cathodic processes at carbon surfaces is critical to developing new strategies for the corrosion protection of [...] Read more.
Carbon-fiber-reinforced polymers (CFRP), being conductive, are capable of supporting cathodic oxygen reduction reactions (ORR) and thus promote galvanic corrosion when coupled to many metallic materials. Hence, understanding cathodic processes at carbon surfaces is critical to developing new strategies for the corrosion protection of multi-material assemblies. In the present work, the electrochemical responses of CFRP, glassy carbon, and HOPG (Highly Ordered Pyrolytic Graphite) have been evaluated in a quiescent 50 mM NaCl solution, and their respective activities towards ORR have been ranked. Employing the averages of the specific charges (CFRP, 129.52 mC cm−2; glassy carbon, 89.95 mC cm−2; HOPG, 60.77 mC cm−2) passed during 1 h polarization of each of the 3 carbon surfaces at −1000 mVSCE in the test media as a ranking criterion, the propensities of the 3 carbon surfaces (CFRP, GC, and HOPG) to support cathodic activities that can lead to anodic metal dissolution on galvanic coupling to metallic materials are ranked thusly; CFRP > GC > HOPG. This ranking is consistent with the trend of capacitance values obtained in this work: CFRP (19.5 to 34.5 μF cm−2), glassy carbon (13.6 to 85.5 μF cm−2), and HOPG (1.4 to 1.8 μF cm−2). A comparison of electrochemical data at potentials relevant to galvanic coupling to metals indicated that at these cathodic potential(s) the CFRP surface is the most electrochemically active of the studied carbon surfaces. On the basis of the values and trends of the electrochemical parameters evaluated, it is postulated that the observed differences in the electrochemical responses of these 3 carbon-rich surfaces to ORR are significantly due to differences in the proportions of edge sites present on each carbon surface. These results could provide valuable insights on plausible strategies for designing carbon surfaces and carbon fiber composites with reduced activity toward ORR for corrosion protection applications or enhanced activity towards ORR for energy applications. Full article
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