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C, Volume 10, Issue 2 (June 2024) – 20 articles

Cover Story (view full-size image): This study pioneers the use of plasma treatment to create metal–carbon nanocomposites, effectively transforming natural graphite into cobalt-doped, nanoporous few-layer graphene. This cutting-edge method significantly boosts the material's functionality for crucial oxygen evolution reactions and supercapacitor energy storage. Despite a surface area reduction from 780 to 480 m²/g, the enhanced nanocomposite demonstrates robust electrochemical performance, evidenced by an overpotential of 290 mV and a Tafel slope of 110 mV/dec. The results underscore the plasma treatment’s potential for scalable, environmentally friendly material synthesis, setting a promising path for future energy-related applications. View this paper
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17 pages, 5721 KiB  
Article
Insights into the Electrocatalytic Activity of Fe,N-Glucose/Carbon Nanotube Hybrids for the Oxygen Reduction Reaction
by Rafael G. Morais, Natalia Rey-Raap, José L. Figueiredo and Manuel F. R. Pereira
C 2024, 10(2), 47; https://doi.org/10.3390/c10020047 - 17 May 2024
Viewed by 239
Abstract
Glucose-derived carbon hybrids were synthesized by hydrothermal treatment in the presence of oxidized carbon nanotubes. Additionally, iron and nitrogen functionalities were incorporated into the carbon structure using different methodologies. The introduction of iron and nitrogen in a single step under a H2 [...] Read more.
Glucose-derived carbon hybrids were synthesized by hydrothermal treatment in the presence of oxidized carbon nanotubes. Additionally, iron and nitrogen functionalities were incorporated into the carbon structure using different methodologies. The introduction of iron and nitrogen in a single step under a H2 atmosphere favored the formation of quaternary nitrogen and oxidized nitrogen, whereas the incorporation of nitrogen under an N2 atmosphere after doping the hybrids with iron mainly produced pyridinic nitrogen. The samples were characterized by scanning electron microscopy, X-ray spectroscopy, adsorption isotherms, inductively coupled plasma optical emission spectrometry, and Raman spectroscopy. The presence of iron and nitrogen in the carbons increases the onset potential toward oxygen reduction in KOH 0.1 mol L−1 by 130 mV (0.83 V), in comparison to carbonized glucose, whereas the reaction mechanism shifts closer to a direct pathway and the formation of HO2 decreases to 25% (3.5 electrons). The reaction rate also increased in comparison to the carbonized glucose, as observed by the decrease in the Tafel slope value from 117 to 61 mV dec−1. Furthermore, the incorporation of iron and nitrogen in a single step enhanced the short-term performance of the prepared electrocatalysts, which may also be due to the higher relative amount of quaternary nitrogen. Full article
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26 pages, 13981 KiB  
Article
Expanded Graphite (EG) Stabilization of Stearic and Palmitic Acid Mixture for Thermal Management of Photovoltaic Cells
by Sereno Sacchet, Francesco Valentini, Alice Benin, Marco Guidolin, Riccardo Po and Luca Fambri
C 2024, 10(2), 46; https://doi.org/10.3390/c10020046 - 15 May 2024
Viewed by 287
Abstract
In this work, passive cooling systems for the revamping of existent silicon photovoltaic (PV) cells were developed and analysed in order to mitigate the efficiency loss caused by temperature rise in the hot season. For this purpose, expanded graphite (EG) was used to [...] Read more.
In this work, passive cooling systems for the revamping of existent silicon photovoltaic (PV) cells were developed and analysed in order to mitigate the efficiency loss caused by temperature rise in the hot season. For this purpose, expanded graphite (EG) was used to stabilize a phase change material (PCM) with a melting temperature close to 53 °C in order to realize thermal management systems (TMSs) able to store heat at constant temperature during melting and releasing it in crystallization. In particular, stearic and palmitic acid mixture (PA-SA) was shape-stabilized in EG at different concentrations (10, 12 and 14 part per hundred ratio) under vacuum into a rotary evaporation apparatus followed by cold compaction; PA-SA leakage was reduced due to its intercalation between the graphite lamellae, and the thermal conductivity necessary to maximize the heat transfer to a bulk TMS was improved via powder cold compaction, which minimizes voids and creates preferential thermal conductive patterns. The composite materials, stable till 150 °C, were tested by differential scanning calorimetry (DSC) at 1 °C/min to precisely determine the phase transition temperatures and the enthalpic content, which was only slightly reduced from 196 J/g of the neat PCM to 169 J/g due to the very low EG fraction necessary for the stabilization. Despite only the 14:100 EG-to-PA-SA ratio, the system’s thermal conductivity was enhanced 40 times with respect to the neat PCM (from 0.2 to 8.3 W/(m K), value never reached in works present in the literature), with a good convergence of the values evaluated through hot disk tests and laser flash analysis (LFA), finding correlation with both graphitic content and density. In order to completely avoid leaking with the consequent dispersion of PCM in the environment during the final application, all the samples were encapsulated in a PE-made film. The mechanical properties were evaluated with compression tests at 30 °C and 80 °C simulating a possible compressive stress deriving from the contact needed to maintain the TMS position on the rear of the PV cells. Finally, the material response was simulated by imposing thermal cycles into a climatic chamber and reproducing the three hottest and coldest days of summer 2022 of two Italian locations, Verona (Veneto, 45° N, 11° E) and Gela (Sicily, 37° N, 14° E), thus highlighting the thermal management effects with delays in temperature increase and daily peak temperature smoothing. The role of EG is strategic for the processing and the properties of the resulting composites in order to realize a proper compromise between the melting enthalpy of PCM and the thermal conductivity enhancement given by EG. Full article
(This article belongs to the Section Carbon Materials and Carbon Allotropes)
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13 pages, 5396 KiB  
Article
Structural and Phase Analysis of the Ausferritic Ductile Cast Iron Matrix Obtained by Heat Treatment and in the Raw State
by Leszek Klimek, Grzegorz Gumienny, Bartłomiej Januszewicz, Radomir Atraszkiewicz and Katarzyna Buczkowska
C 2024, 10(2), 45; https://doi.org/10.3390/c10020045 - 14 May 2024
Viewed by 281
Abstract
This paper presents a comparative analysis of ausferritic ductile cast iron matrix obtained through heat treatment and in its raw state. Ausferrite without heat treatment was achieved by modifying the chemical composition, while nodular graphite was produced using Inmold technology. The presence of [...] Read more.
This paper presents a comparative analysis of ausferritic ductile cast iron matrix obtained through heat treatment and in its raw state. Ausferrite without heat treatment was achieved by modifying the chemical composition, while nodular graphite was produced using Inmold technology. The presence of compacted graphite in the as-cast ausferritic cast iron was attributed to elements that impede the crystallization of nodular graphite. This study demonstrates that an ausferritic matrix in ductile cast iron can be achieved by incorporating molybdenum in conjunction with nickel or copper. Thermal and derivative analysis (TDA) revealed a minor thermal effect during the transformation of austenite into bainitic ferrite in as-cast ausferritic cast iron. Furthermore, the transformation of austenite in cast iron containing nickel was observed to occur at a temperature of approximately 60 °C higher than in cast iron with copper. The structure of bainitic ferrite platelets in as-cast ausferritic ductile cast iron resembled that of Austempered Ductile Iron (ADI). It was revealed that the amount of austenite in as-cast ausferritic ductile cast iron is more than double that in ADI. The carbon content of austenite was estimated theoretically, revealing that alloying additives in the as-cast ausferritic ductile cast iron reduce the solubility of carbon in austenite, thereby significantly influencing the properties of the cast iron. Full article
(This article belongs to the Section Carbon Materials and Carbon Allotropes)
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14 pages, 7549 KiB  
Article
Gate-Tunable Asymmetric Quantum Dots in Graphene-Based Heterostructures: Pure Valley Polarization and Confinement
by Adel Belayadi and Panagiotis Vasilopoulos
C 2024, 10(2), 44; https://doi.org/10.3390/c10020044 - 8 May 2024
Viewed by 464
Abstract
We explore the possibility of attaining valley-dependent tunnelling and confinement using proximity-induced spin-orbit couplings (SOCs) in graphene-based heterostructures. We consider gate-tunable asymmetric quantum dots (AQDs) on graphene heterostructures and exhibiting a C3v and/or C6v symmetry. By employing a tight-binding [...] Read more.
We explore the possibility of attaining valley-dependent tunnelling and confinement using proximity-induced spin-orbit couplings (SOCs) in graphene-based heterostructures. We consider gate-tunable asymmetric quantum dots (AQDs) on graphene heterostructures and exhibiting a C3v and/or C6v symmetry. By employing a tight-binding model, we explicitly reveal a pure valley confinement and valley signal in AQDs by streaming the valley local density, leading to valley-charge separation in real space. The confinement of the valley quasi-bound states is sensitive to the locally induced SOCs and to the spatial distribution of the induced AQDs; it is also robust against on-site disorder. The adopted process of attaining a pure valley-Hall conductivity and confinement with zero charge currents is expected to provide more options towards valley-dependent electron optics. Full article
(This article belongs to the Section Carbon Skeleton)
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19 pages, 4721 KiB  
Article
Stimulating Mesoporous Characteristics of Activated Carbon through Pyrolysis of Compacted Hydroxyethyl Cellulose—A Showcase for H2S Removal
by Fuxiang Chen and Liang Hong
C 2024, 10(2), 43; https://doi.org/10.3390/c10020043 - 6 May 2024
Viewed by 616
Abstract
Activated carbon (AC) serves as extensively researched adsorbents, with numerous established methods for their preparation. This study originated from the hypothesis that compressing a hydrocarbon substance to create a densely compacted pellet, known as pelletizing, would enhance the development of porous features of [...] Read more.
Activated carbon (AC) serves as extensively researched adsorbents, with numerous established methods for their preparation. This study originated from the hypothesis that compressing a hydrocarbon substance to create a densely compacted pellet, known as pelletizing, would enhance the development of porous features of the resulting AC. The anticipated enhancement is attributed to the rise in spatial proximity amidst HEC polymer chains within the bulk of the pellet, which facilitates aromatization both in extent and functionality. 2-Hydroxyethyl cellulose (HEC) pellets were prepared by adjusting the duration of load holding, aiming to increase the packing density of HEC polymer chains via creeping. The BET analysis of the resulting AC samples demonstrates the efficacy of compression on HEC pellets in enhancing their porous properties. The FE-SEM study revealed diverse AC surface morphologies that are associated with a set of specific pelletizing conditions. The 13C NMR spectroscopy for carbon skeletons, FT-IR spectroscopy for organic functionality, and XPS spectroscopy for surface composition collectively report the leverage of compression treatment before pyrolyzing HEC pellets. Furthermore, the assessment of hydrogen sulfide adsorption by the resulting AC samples revealed distinctive breakthrough curves, providing validation for the proposed compression effect. Full article
(This article belongs to the Section Carbon Materials and Carbon Allotropes)
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13 pages, 54733 KiB  
Article
On the Mechanical Properties and Fracture Patterns of Biphenylene-Based Nanotubes: A Reactive Molecular Dynamics Study
by Hudson Rodrigues Armando, Wiliam Ferreira Giozza, Luiz Antonio Ribeiro Junior and Marcelo Lopes Pereira Junior
C 2024, 10(2), 42; https://doi.org/10.3390/c10020042 - 6 May 2024
Viewed by 605
Abstract
Carbon-based materials have garnered significant attention since the groundbreaking synthesis of graphene. The exploration of novel 2D carbon allotropes has led to the discovery of materials with intrinsic properties distinct from graphene. Within this context, the biphenylene network (BPN) was successfully synthesized. In [...] Read more.
Carbon-based materials have garnered significant attention since the groundbreaking synthesis of graphene. The exploration of novel 2D carbon allotropes has led to the discovery of materials with intrinsic properties distinct from graphene. Within this context, the biphenylene network (BPN) was successfully synthesized. In this study, we used molecular dynamics (MD) simulations with the Reactive Force Field (ReaxFF) to delve into the thermomechanical properties and fracture patterns of biphenylene-based nanotubes (BPN-NTs) exhibiting armchair (AC-BPN-NT) and zigzag (ZZ-BPN-NT) chiralities. Throughout the longitudinal deformation process, we observed significant morphological transformations preceding the structural fracture of the system. These transformations unfolded in distinct inelastic phases. In both cases, AC- and ZZ-BPN-NT, stress accumulation in four-membered rings led to the creation of octagonal structures; however, in AC, this occurs in the fracture region, subsequently causing the presence of nanopores. On the other hand, for ZZ-BPN-NT, stress accumulation in the rectangular rings occurred in bonds parallel to the deformation, with elongated octagonal structures. The Young’s modulus of these nanotubes ranged from 746 to 1259 GPa, with a melting point of around 4000 K. Our results also explore the influence of diameter and curvature, drawing comparisons with BPN monolayers. Full article
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11 pages, 3718 KiB  
Article
Effect of Hybridization of Carbon Fibers on Mechanical Properties of Cellulose Fiber–Cement Composites: A Response Surface Methodology Study
by Gabriel L. Insaurriaga, Cristian C. Gomes, Felipe V. Ribeiro, Gustavo L. Calegaro, Thamires A. Silveira, Lóren F. Cruz, Joziel A. Cruz, Sandro C. Amico and Rafael A. Delucis
C 2024, 10(2), 41; https://doi.org/10.3390/c10020041 - 30 Apr 2024
Viewed by 650
Abstract
Fiber-reinforced cement composites, particularly those incorporating natural fibers like cellulose, have gained attention for their potential towards more sustainable construction. However, natural fibers present inherent deficiencies in mechanical properties and can benefit from hybridization with carbon fibers. This study focuses on the incorporation [...] Read more.
Fiber-reinforced cement composites, particularly those incorporating natural fibers like cellulose, have gained attention for their potential towards more sustainable construction. However, natural fibers present inherent deficiencies in mechanical properties and can benefit from hybridization with carbon fibers. This study focuses on the incorporation of cellulose and carbon fibers, in varying contents, into fibrocement composites, employing a Response Surface Methodology (RSM) to optimize the material characteristics. The methodology involves testing, encompassing flexural tensile, compression, and fracture toughness tests. The results indicate an increasing trend in flexural strength for higher carbon fiber content, peaking near 5%. A plateau in flexural strength is observed between 1.2% and 3.6% carbon fiber content, suggesting a range where mechanical properties stabilize. Compressive strength shows a plateau between 1.2 and 3.6% and reaches its highest value (≈33 MPa) at a carbon fiber content greater than 4.8%, and fracture toughness above 320 MPa·m1/2 is achieved with carbon fiber content above 3.6%. This study offers insights into optimizing the synergistic effects of cellulose and carbon fibers in fibrocement composites. Full article
(This article belongs to the Special Issue High-Performance Carbon Materials and Their Composites)
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13 pages, 5520 KiB  
Article
Tuning the Dynamic Thermal Parameters of Nanocarbon Ionanofluids: A Photopyroelectric Study
by Mohanachandran Nair Sindhu Swapna, Carmen Tripon, Alexandra Farcas, Dorin Nicolae Dadarlat, Dorota Korte and Sankaranarayana Iyer Sankararaman
C 2024, 10(2), 40; https://doi.org/10.3390/c10020040 - 26 Apr 2024
Viewed by 567
Abstract
The present work delineates the tailoring of the thermal effusivity and diffusivity of the novel class of heat transfer fluids—ionanofluids—by the incorporation of nanocarbons like diesel soot (DS), camphor soot (CS), carbon nanotubes (CN), and graphene (GR). When the thermal diffusivity delivers information [...] Read more.
The present work delineates the tailoring of the thermal effusivity and diffusivity of the novel class of heat transfer fluids—ionanofluids—by the incorporation of nanocarbons like diesel soot (DS), camphor soot (CS), carbon nanotubes (CN), and graphene (GR). When the thermal diffusivity delivers information on the thermal energy propagation, the thermal effusivity concerns the energy exchange at the interface, enabling energy-efficient thermal system design. The nanocarbons are subjected to morphological characterisation by field emission scanning electron microscopy. Fourier-transform infrared and Raman spectroscopic analyses confirm functional groups and vibrational bands. The microcrystalline size and graphiticity are also understood from the Raman spectrum. Ionanofluids prepared by dispersing nanocarbons into an ionic liquid base 1-Butyl-3-methylimidazolium methyl sulfate (BMMS) are analysed by nondestructive photopyroelectric calorimetry (PPE). The PPE analysis of ionanofluids demonstrates that nanocarbons influence thermal parameters in the base fluid, with soot ionanofluids exhibiting increased thermal effusivity and diffusivity due to their various carbon allotropic composition. This study underscores the importance of selecting the appropriate carbon allotrope for tailoring ionanofluids’ thermal properties, providing insights into manipulating these properties for enhanced performance across various industrial applications. Full article
(This article belongs to the Section Carbon Materials and Carbon Allotropes)
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18 pages, 3429 KiB  
Article
Low-Temperature Deposition of Diamond Films by MPCVD with Graphite Paste Additive
by Stephen Yang-En Guu, Fu-Cheng Lin, Yu-Sen Chien, Alen Jhang and Yon-Hua Tzeng
C 2024, 10(2), 39; https://doi.org/10.3390/c10020039 - 16 Apr 2024
Viewed by 907
Abstract
Modern integrated circuits (ICs) take advantage of three-dimensional (3D) nanostructures in devices and interconnects to achieve high-speed and ultra-low-power performance. The choice of electrical insulation materials with excellent dielectric strength, electrical resistivity, strong mechanical strength, and high thermal conductivity becomes critical. Diamond possesses [...] Read more.
Modern integrated circuits (ICs) take advantage of three-dimensional (3D) nanostructures in devices and interconnects to achieve high-speed and ultra-low-power performance. The choice of electrical insulation materials with excellent dielectric strength, electrical resistivity, strong mechanical strength, and high thermal conductivity becomes critical. Diamond possesses these properties and is recently recognized as a promising dielectric material for the fabrication of advanced ICs, which are sensitive to detrimental high-temperature processes. Therefore, a high-rate low-temperature deposition technique for large-grain, high-quality diamond films of the thickness of a few tens to a few hundred nanometers is desirable. The diamond growth rate by microwave plasma chemical vapor deposition (MPCVD) decreases rapidly with lowering substrate temperature. In addition, the thermal conductivity of non-diamond carbon is much lower than that of diamond. Furthermore, a small-grain diamond film suffers from poor thermal conductivity due to frequent phonon scattering at grain boundaries. This paper reports a novel MPCVD process aiming at high growth rate, large grain size, and high sp3/sp2 ratio for diamond films deposited on silicon. Graphite paste containing nanoscale graphite and oxy-hydrocarbon binder and solvent vaporizes and mixes with gas feeds of hydrogen, methane, and carbon dioxide to form plasma. Rapid diamond growth of diamond seeds at 450 °C by the plasma results in large-grained diamond films on silicon at a high deposition rate of 200 nm/h. Full article
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12 pages, 7554 KiB  
Article
Observation of Structural Changes during Oxidation of Black and Brown Soot Using Raman Spectroscopy
by Kim Cuong Le, Saga Bergqvist, Jonatan Henriksson and Per-Erik Bengtsson
C 2024, 10(2), 38; https://doi.org/10.3390/c10020038 - 15 Apr 2024
Viewed by 706
Abstract
In this study, Raman spectroscopy has been used to evaluate the evolution of the structural modification of soot during oxidation processes at various preset temperatures up to 700 °C. Two types of well-characterized mini-CAST soot, representing black soot and brown soot, were examined. [...] Read more.
In this study, Raman spectroscopy has been used to evaluate the evolution of the structural modification of soot during oxidation processes at various preset temperatures up to 700 °C. Two types of well-characterized mini-CAST soot, representing black soot and brown soot, were examined. The major difference between the signals from the two types of soot was the higher photoluminescence (PL) signal for brown soot compared with black soot, in addition to some variations in the first-order Raman signatures such as oxygenated groups and their evolutions during thermal oxidation treatment. An interesting observation was the increase in the PL signal for brown soot at increasing temperatures up to 150 °C probably due to the formation of small oxidized polycyclic aromatic hydrocarbon and defects, followed by a decrease in the PL signal until the soot was fully oxidized. We also demonstrated that brown soot is prone to oxidation in ex situ measurements, a factor that should be considered in the Raman analysis of soot. Full article
(This article belongs to the Section Combustion Emissions)
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15 pages, 2262 KiB  
Article
Discrete Multiwalled Carbon Nanotubes for Versatile Intracellular Transport of Functional Biomolecular Complexes
by Kevin Castillo, Aaron Tasset, Milos Marinkovic and Aaron Foote
C 2024, 10(2), 37; https://doi.org/10.3390/c10020037 - 15 Apr 2024
Viewed by 778
Abstract
In recent years, carbon nanotubes have emerged as a potentially revolutionary material with numerous uses in biomedical applications. Compared to other nanoparticles, discrete multiwalled carbon nanotubes (dMWCNTs) have been shown to exhibit advantageous characteristics such as a high surface area-to-volume ratio, biocompatibility, and [...] Read more.
In recent years, carbon nanotubes have emerged as a potentially revolutionary material with numerous uses in biomedical applications. Compared to other nanoparticles, discrete multiwalled carbon nanotubes (dMWCNTs) have been shown to exhibit advantageous characteristics such as a high surface area-to-volume ratio, biocompatibility, and unique chemical and physical properties. dMWCNTs can be modified to load various molecules such as proteins and nucleic acids and are capable of crossing the cell membrane, making them attractive delivery vehicles for biomolecules. To investigate this, we measured the impact of dMWCNTs on the number of live and dead cells present during different stages of cell proliferation. Furthermore, we used transmission electron microscopy to produce evidence suggesting that dMWCNTs enter the cytoplasm of mammalian cells via an endocytosis-like process and ultimately escape into the cytoplasm. And lastly, we used live-cell staining, qPCR, and a T-cell activation detection assay to quantify the use of dMWCNTs as a delivery vehicle for a toxic, membrane-impermeable peptide, mRNA, siRNA, and a T-cell activating synthetic dsRNA. We demonstrate successful delivery of each payload into a range of cell types, providing further evidence of dMWCNTs as a versatile delivery platform for biomolecular cargo. Full article
(This article belongs to the Special Issue Carbon Nanohybrids for Biomedical Applications)
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13 pages, 9545 KiB  
Article
RHEED Study of the Epitaxial Growth of Silicon and Germanium on Highly Oriented Pyrolytic Graphite
by Kirill A. Lozovoy, Vladimir V. Dirko, Olzhas I. Kukenov, Arseniy S. Sokolov, Konstantin V. Krukovskii, Mikhail S. Snegerev, Alexey V. Borisov, Yury V. Kistenev and Andrey P. Kokhanenko
C 2024, 10(2), 36; https://doi.org/10.3390/c10020036 - 10 Apr 2024
Viewed by 886
Abstract
Two-dimensional silicon (silicene) and germanium (germanene) have attracted special attention from researchers in recent years. At the same time, highly oriented pyrolytic graphite (HOPG) and graphene are some of the promising substrates for growing silicene and germanene. However, to date, the processes occurring [...] Read more.
Two-dimensional silicon (silicene) and germanium (germanene) have attracted special attention from researchers in recent years. At the same time, highly oriented pyrolytic graphite (HOPG) and graphene are some of the promising substrates for growing silicene and germanene. However, to date, the processes occurring during the epitaxial growth of silicon and germanium on the surface of such substrates have been poorly studied. In this work, the epitaxial growth of silicon and germanium is studied directly during the process of the molecular beam epitaxy deposition of material onto the HOPG surface by reflection high-energy electron diffraction (RHEED). In addition, the obtained samples are studied by Raman spectroscopy and scanning electron microscopy. A wide range of deposition temperatures from 100 to 800 °C is considered and temperature intervals are determined for various growth modes of silicon and germanium on HOPG. Conditions for amorphous and polycrystalline growth are distinguished. Diffraction spots corresponding to the lattice constants of silicene and germanene are identified that may indicate the presence of areas of graphene-like 2D phases during epitaxial deposition of silicon and germanium onto the surface of highly oriented pyrolytic graphite. Full article
(This article belongs to the Special Issue Advances in Bilayer Graphene)
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15 pages, 3287 KiB  
Article
Ultrasmall Glucose-Functionalized Au-Carbon Nanohybrids: Exploiting the Warburg Effect to Image Tumors by Multimodal CT/Fluorescence Imaging
by Roberta Cillari, Sergio Scirè, Gennara Cavallaro and Nicolò Mauro
C 2024, 10(2), 35; https://doi.org/10.3390/c10020035 - 4 Apr 2024
Viewed by 1042
Abstract
Utilizing glucose as a targeting agent represents a pioneering approach in selectively directing nanoparticles towards cancer cells, capitalizing on the pronounced glucose uptake observed in tumors attributable to the Warburg effect. In this study, we have successfully adopted this targeting strategy to facilitate [...] Read more.
Utilizing glucose as a targeting agent represents a pioneering approach in selectively directing nanoparticles towards cancer cells, capitalizing on the pronounced glucose uptake observed in tumors attributable to the Warburg effect. In this study, we have successfully adopted this targeting strategy to facilitate the specific uptake of advanced nanotools, comprising carbon nanocrystals incorporating gold seeds (AuCDs). Leveraging the advantageous optical and size-related properties of carbon nanodots in conjunction with gold-mediated X-ray attenuation capabilities, these hybrid nanomaterials have been engineered as contrast agents for a bi-modal imaging modality, exploiting the synergistic benefits of fluorescence imaging and X-ray computed tomography. Notably, for the synthesis of AuCDs, we present, for the first time, the incorporation of gold seeds within the molecular precursors of carbon nanodots during their solvothermal synthesis process, showcasing the efficacy of this synthetic pathway in yielding nanoscale carbon structures incorporating bioeliminable gold ultrasmall nanoparticles (d < 5 nm). Subsequently, we employed an azido-alkyne click chemistry reaction to functionalize the nanoparticle surface with 2-deoxy-D-glucose as a targeting moiety. The demonstrated cancer-targeting proficiency, as assessed via fluorescence imaging, renders the proposed nanosystem highly promising for a spectrum of applications in precision anticancer theranostics, encompassing both diagnostic and therapeutic endeavors. Full article
(This article belongs to the Special Issue Carbon Nanohybrids for Biomedical Applications)
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1 pages, 135 KiB  
Editorial
Editorial for C—Journal of Carbon Research in 2023
by Craig E. Banks
C 2024, 10(2), 34; https://doi.org/10.3390/c10020034 - 2 Apr 2024
Viewed by 776
Abstract
Our journal, C—Journal of Carbon Research (https://www.mdpi.com/journal/carbon), is an international, scientific, peer-reviewed, open access journal on carbon research, published quarterly online by MDPI [...] Full article
14 pages, 2493 KiB  
Article
Evaluating the Cytotoxicity of Functionalized MWCNT and Microbial Biofilm Formation on PHBV Composites
by Thaís Larissa do Amaral Montanheiro, Vanessa Modelski Schatkoski, Denisse Esther Mallaupoma Camarena, Thais Cardoso de Oliveira, Diego Morais da Silva, Mariana Raquel da Cruz Vegian, Luiz Henrique Catalani, Cristiane Yumi Koga-Ito and Gilmar Patrocínio Thim
C 2024, 10(2), 33; https://doi.org/10.3390/c10020033 - 31 Mar 2024
Viewed by 1000
Abstract
This study focuses on the cytotoxic evaluation of functionalized multi-walled carbon nanotubes (MWCNT) and microbial biofilm formation on poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) nanocomposites incorporating MWCNTs functionalized with gamma-aminobutyric acid (GABA) and carboxyl groups. The materials were characterized for cytotoxicity to fibroblasts and antimicrobial [...] Read more.
This study focuses on the cytotoxic evaluation of functionalized multi-walled carbon nanotubes (MWCNT) and microbial biofilm formation on poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) nanocomposites incorporating MWCNTs functionalized with gamma-aminobutyric acid (GABA) and carboxyl groups. The materials were characterized for cytotoxicity to fibroblasts and antimicrobial effects against Escherichia coli, Staphylococcus aureus and Candida albicans. The functionalization of MWCNTs was performed through oxidation (CNT-Ox) and GABA attachment (CNT-GB). The PHBV/CNT nanocomposites were produced via melt mixing. All MWCNT suspensions showed non-toxic behaviors after 24 h of incubation (viability higher than 70%); however, prolonged incubation and higher concentrations led to increased cytotoxicity. The antibacterial potential of PHBV/CNT nanocomposites against S. aureus showed a reduction in biofilm formation of 64% for PHBV/CNT-GB and 20% for PHBV/CNT-Ox, compared to neat PHBV. Against C. albicans, no reduction was observed. The results indicate promising applications for PHBV/CNT nanocomposites in managing bacterial infections, with GABA-functionalized CNTs showing enhanced performance. Full article
(This article belongs to the Special Issue Carbon Nanohybrids for Biomedical Applications)
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13 pages, 2542 KiB  
Article
Supercapacitor Performance of MXene-Coated Carbon Nanofiber Electrodes
by Seon Kyung Kim, Seung Ah Kim, Yoon Soo Han and Kyung-Hye Jung
C 2024, 10(2), 32; https://doi.org/10.3390/c10020032 - 29 Mar 2024
Viewed by 945
Abstract
MXenes consisting of thin layers of transition metal carbides or nitrides are good candidates for electrode materials due to their excellent electrical conductivity and fast ion transfer. Electrospun carbon nanofibers are highly porous and electrically conductive, making them attractive for electrode materials. In [...] Read more.
MXenes consisting of thin layers of transition metal carbides or nitrides are good candidates for electrode materials due to their excellent electrical conductivity and fast ion transfer. Electrospun carbon nanofibers are highly porous and electrically conductive, making them attractive for electrode materials. In this study, free-standing electrodes were prepared by the dip-coating of carbon nanofibers (CNFs) in the MXene (Ti3C2) colloidal solution, which was synthesized via the wet-etching of MAX (Ti3AlC2) phase, and their chemical structures were investigated by X-ray diffraction and Fourier transform infrared spectroscopy. In addition, scanning and transmission electron microscopy were used to investigate the morphological and crystallographic features of MXene-coated CNFs. Surface area and pore volumes were investigated by nitrogen adsorption/desorption measurements. Supercapacitor performance was studied by assembling a 3-electrode system with 1M aqueous sodium sulfate solution as an electrolyte. MXene-coated CNFs exhibited a maximum specific capacitance of 514 F/g at 0.5 A/g, with energy and power densities of 71.4 Wh/kg at 0.5 A/g and 2.3 kW/kg at 5 A/g, respectively, which are relevantly higher compared to the pristine CNFs due to the pseudocapacitive behavior of MXenes. They also showed comparable cyclic stability during 5000 cycles with the CNFs. This result indicates that MXene-coated carbon nanofibers can be effective electrode materials for electrochemical energy storage. Full article
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12 pages, 5801 KiB  
Article
Plasma-Treated Cobalt-Doped Nanoporous Graphene for Advanced Electrochemical Applications
by Florian Knabl, Nikolaos Kostoglou, Ram K. Gupta, Afshin Tarat, Steven Hinder, Mark Baker, Claus Rebholz and Christian Mitterer
C 2024, 10(2), 31; https://doi.org/10.3390/c10020031 - 26 Mar 2024
Viewed by 972
Abstract
Metal–carbon nanocomposites are identified as key contenders for enhancing water splitting through the oxygen evolution reaction and boosting supercapacitor energy storage capacitances. This study utilizes plasma treatment to transform natural graphite into nanoporous few-layer graphene, followed by additional milling and plasma steps to [...] Read more.
Metal–carbon nanocomposites are identified as key contenders for enhancing water splitting through the oxygen evolution reaction and boosting supercapacitor energy storage capacitances. This study utilizes plasma treatment to transform natural graphite into nanoporous few-layer graphene, followed by additional milling and plasma steps to synthesize a cobalt–graphene nanocomposite. Comprehensive structural characterization was conducted using scanning and transmission electron microscopy, X-ray diffraction, Raman spectroscopy, gas sorption analysis and X-ray photoelectron spectroscopy. Electrochemical evaluations further assessed the materials’ oxygen evolution reaction and supercapacitor performance. Although the specific surface area of the nanoporous carbon decreases from 780 to 480 m2/g in the transition to the resulting nanocomposite, it maintains its nanoporous structure and delivers a competitive electrochemical performance, as evidenced by an overpotential of 290 mV and a Tafel slope of 110 mV/dec. This demonstrates the efficacy of plasma treatment in the surface functionalization of carbon-based materials, highlighting its potential for large-scale chemical-free application due to its environmental friendliness and scalability, paving the way toward future applications. Full article
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18 pages, 3591 KiB  
Article
Refining and Validating Thermogravimetric Analysis (TGA) for Robust Characterization and Quality Assurance of Graphene-Related Two-Dimensional Materials (GR2Ms)
by Dusan Losic, Farzaneh Farivar and Pei Lay Yap
C 2024, 10(2), 30; https://doi.org/10.3390/c10020030 - 26 Mar 2024
Viewed by 933
Abstract
Graphene-related two-dimensional materials available on the global market are manufactured using various production methods, with significant variations in properties and qualities causing serious concerns for the emerging multi-billion graphene industry. To address the limitations of conventional characterization methods probing the properties of individual [...] Read more.
Graphene-related two-dimensional materials available on the global market are manufactured using various production methods, with significant variations in properties and qualities causing serious concerns for the emerging multi-billion graphene industry. To address the limitations of conventional characterization methods probing the properties of individual graphene particles which may overlook the presence of non-graphene carbon impurities at a large (bulk) scale, this paper presents the refining thermogravimetric analysis as a complementary method for the reliable chemical characterization and quality control of graphene powders. A systematic parametric investigation of key experimental conditions such as sample mass and loading, heating rate, and gas environment and flow rate is performed to identify optimized settings for reliable thermal gravimetric measurements. These optimized conditions are evaluated through a series of comparative characterizations using industrially produced graphene, graphene oxide, and reduced graphene oxide powders, including their common carbon impurities. The ability of this method to provide both qualitative and quantitative analyses for characterizing graphene-related materials is confirmed. The optimized method is finally validated through an International Laboratory Comparison study and subsequently incorporated into a new standard. This low-cost, industry-affordable, and complementary characterization method is expected to enhance the quality control of manufactured graphene materials and make a valuable contribution to the growing graphene industry. Full article
(This article belongs to the Section Carbon Materials and Carbon Allotropes)
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35 pages, 11977 KiB  
Review
Fused Deposition Modelling of Thermoplastic Polymer Nanocomposites: A Critical Review
by Taha Sheikh and Kamran Behdinan
C 2024, 10(2), 29; https://doi.org/10.3390/c10020029 - 25 Mar 2024
Viewed by 1385
Abstract
Fused deposition modelling (FDM) has attracted researchers’ interest in myriads of applications. The enhancement of its part using fillers to print nanocomposites is a cutting-edge domain of research. Industrial acceptance is still a challenge, and researchers are investigating different nanofillers and polymer matrix [...] Read more.
Fused deposition modelling (FDM) has attracted researchers’ interest in myriads of applications. The enhancement of its part using fillers to print nanocomposites is a cutting-edge domain of research. Industrial acceptance is still a challenge, and researchers are investigating different nanofillers and polymer matrix combinations to investigate FDM-printed nanocomposites. Carbon nanotubes, graphene, and cellulose are heavily studied nanofillers because of their astonishing properties, biocompatibility, and ability to tailor the final performance of the FDM-printed nanocomposite part. This work presents a comprehensive review of polymer nanocomposites based on these nanofillers. Important examples, case studies, and results are discussed and compared to elaborate the understanding of the processing of nanocomposites, filaments, printing, and the characterisation of these nanocomposites. A detailed and exhaustive discussion of the prospective computational models, with challenges and a future road map, is provided, enabling the scientific community to understand these nanocomposites and their FDM processing for wider industrial applications and acceptance. Full article
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14 pages, 10809 KiB  
Article
Laser-Induced Copper/Carbon Nanocomposite from Anodically Electrodeposited Chitosan for H2O2 Sensing
by Usama Zafar, Prince Kumar Rai, Ankur Gupta, Jan G. Korvink, Vlad Badilita and Monsur Islam
C 2024, 10(2), 28; https://doi.org/10.3390/c10020028 - 24 Mar 2024
Viewed by 1165
Abstract
This work presents anodically electrodeposited copper (Cu)/chitosan gel as a novel precursor for synthesizing a Cu/carbon nanocomposite through laser-induced carbonization. Metal/carbon nanocomposites offering advantageous properties compared to their individual counterparts stand out in various applications, particularly in those involving electrochemical phenomena. However, their [...] Read more.
This work presents anodically electrodeposited copper (Cu)/chitosan gel as a novel precursor for synthesizing a Cu/carbon nanocomposite through laser-induced carbonization. Metal/carbon nanocomposites offering advantageous properties compared to their individual counterparts stand out in various applications, particularly in those involving electrochemical phenomena. However, their synthesis often suffers from complicated and time-consuming synthesis procedures. Here, we integrate anodic electrodeposition and laser-induced carbonization to yield a rapid, simple, and inexpensive procedure for synthesizing metal/carbon nanocomposite. A precursor composite involving Cu-coordinated chitosan film is achieved through anodic electrodeposition on a copper anode. Irradiation by an infrared laser with optimized parameters results in the thermochemical decomposition of the Cu/chitosan composite, rapidly forming a nanocomposite material featuring highly graphitized and porous carbon materials. Elemental mapping confirms the formation of the nanocomposite, although no crystalline phases of copper are observed during X-ray diffraction. This can be attributed to the rapid nature of the laser-carbonization process. The nanocomposite material is further demonstrated for electrochemical sensing of hydrogen peroxide (H2O2), exhibiting a sensitivity of 2.65 mM−1 for concentrations ranging from 0.01 mM to 0.1 mM H2O2, and 0.01 ± 0.01 mM−1 for concentrations from 0.1 to 10 mM H2O2. These sensitivities are comparable to other non-enzymatic H2O2 biosensors. The finding of this work signifies a rapid and facile method for synthesizing metal/carbon nanocomposites with strong implications for the field of biosensors. Full article
(This article belongs to the Special Issue Micro/Nanofabrication of Carbon-Based Devices and Their Applications)
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