Journal Description
C — Journal of Carbon Research
C
— Journal of Carbon Research is an international, scientific, peer-reviewed, open access journal on carbon research, published quarterly online by MDPI. The Spanish Carbon Group (GEC) is affiliated with C — Journal of Carbon Research and its members receive discounts on article processing charges.
- Open Access— free for readers, with article processing charges (APC) paid by authors or their institutions.
- High Visibility: indexed within ESCI (Web of Science), Scopus, CAPlus / SciFinder, and other databases.
- Journal Rank: JCR - Q2 (Materials Science, Multidisciplinary) / CiteScore - Q2 (Environmental Science (miscellaneous))
- Rapid Publication: manuscripts are peer-reviewed and a first decision is provided to authors approximately 15.7 days after submission; acceptance to publication is undertaken in 4.6 days (median values for papers published in this journal in the first half of 2026).
- Recognition of Reviewers: reviewers who provide timely, thorough peer-review reports receive vouchers entitling them to a discount on the APC of their next publication in any MDPI journal, in appreciation of the work done.
Impact Factor:
4.3 (2025);
5-Year Impact Factor:
4.2 (2025)
Latest Articles
Structure–Property Assessment of Graphene Oxide in Gypsum/Plaster: Effects of Thermal Treatments on the Water and Mechanical Resistance
C 2026, 12(3), 62; https://doi.org/10.3390/c12030062 - 29 Jul 2026
Abstract
A structure–property assessment of coating plaster reinforced with a low dosage (0.01 wt%) of graphene oxide (GO) was investigated to address the intrinsic mechanical and thermal limitations of gypsum in civil construction. Nanocomposite specimens were characterized in terms of hydration kinetics (setting time),
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A structure–property assessment of coating plaster reinforced with a low dosage (0.01 wt%) of graphene oxide (GO) was investigated to address the intrinsic mechanical and thermal limitations of gypsum in civil construction. Nanocomposite specimens were characterized in terms of hydration kinetics (setting time), wettability (water contact angle), and compressive behavior across a range of post-fabrication thermal treatments at 200 °C, 250 °C, and 300 °C. Although the incorporation of 0.01 wt% GO maintained the ultimate compressive strength of the matrix (~13.8 MPa), it fundamentally transformed the pre-yield behavior, doubling the initial structural stiffness (slope) from 8.7 to 18.7 MPa·mm−1. This mechanical enhancement suggests the role of GO as a structural anchor capable of bridging micro-voids and restricting microcrack propagation. Beyond 200 °C, phase transformation via gypsum dehydration into basanite and anhydrite phases, validated by X-ray diffraction (XRD) and scanning electron microscopy (SEM), led to a severe reduction in compressive strength for both neat and reinforced matrices. Crucially, however, the GO-reinforced composites retained a 76% higher structural stiffness compared to the neat plaster within this post-thermal regime. Additionally, thermal activation at 200 °C induced a critical surface modification, elevating the water contact angle to 68.1° because of partial GO thermal reduction, as confirmed by coupled TG/FTIR analysis. These findings demonstrate that while GO does not suppress the intrinsic chemical dehydration of the calcium sulfate matrix, it provides vital mechanical stabilization to the crystalline network, significantly enhancing rigidity and deformation resistance under severe thermal stress.
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(This article belongs to the Section Carbon Materials and Carbon Allotropes)
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Open AccessArticle
rGO/ZnO/CuO Hybrid-Coated Stretch Textiles for Flexible Thermoelectric and Electrothermal Applications
by
Bilal Alam Khan, Muhammad Zaman Khan, Azam Ali and Shahid Ali Shaukat
C 2026, 12(3), 61; https://doi.org/10.3390/c12030061 - 22 Jul 2026
Abstract
Flexible thermoelectric textiles have emerged as promising materials for wearable energy harvesting and electrothermal applications because they combine mechanical flexibility with the ability to convert low-grade heat into electrical energy. In this study, reduced graphene oxide/zinc oxide/copper oxide (rGO/ZnO/CuO) hybrid nanocomposites were synthesized
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Flexible thermoelectric textiles have emerged as promising materials for wearable energy harvesting and electrothermal applications because they combine mechanical flexibility with the ability to convert low-grade heat into electrical energy. In this study, reduced graphene oxide/zinc oxide/copper oxide (rGO/ZnO/CuO) hybrid nanocomposites were synthesized and deposited onto Cotton–Nylon–Spandex (80:15:05) stretch fabrics using a silicone elastomer-assisted coating process to develop flexible conductive textiles. The influence of nanocomposite loading (2–8 g/100 mL elastomer) on the structural, electrical, thermal, and thermoelectric properties of the coated fabrics was systematically investigated. SEM, EDX, XRD, and Raman analyses confirmed the successful formation and uniform distribution of the rGO/ZnO/CuO hybrid coating on the textile substrate. Increasing the nanocomposite loading progressively reduced the electrical resistance from approximately 42 to 18 MΩ, indicating the formation of an interconnected conductive network, while the Seebeck coefficient increased from 0.049 to 0.056 mV K−1 (49–56 μV K−1). The measured effective thermal conductivity of the coated textile decreased from approximately 12 to 2.68 W m−1 K−1, reflecting changes in the thermal transport behavior of the composite coating. The coated fabrics also exhibited stable electrical performance under repeated bending, stretching (up to 80% strain), and washing, together with improved thermal stability and uniform Joule-heating behavior. These results demonstrate that the rGO/ZnO/CuO hybrid coating provides an effective strategy for developing flexible, mechanically durable, and multifunctional conductive textiles with potential applications in wearable thermoelectric energy harvesting and smart heating systems.
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(This article belongs to the Section Carbon Materials and Carbon Allotropes)
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Open AccessArticle
Influence of Manufacturing Process and Material Configuration on the Mechanical and Elastic Properties of Kevlar–Carbon Hybrid Laminates
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Ciprian Ionuț Morăraș, Teodor Adrian Badea, Viorel Goanță, Lucia Raluca Maier, Alexa-Andreea Crisan and Paul Doru Barsanescu
C 2026, 12(3), 60; https://doi.org/10.3390/c12030060 - 21 Jul 2026
Abstract
The present study investigates the combined influence of manufacturing route and material configuration on the mechanical, elastic, viscoelastic, and impact behavior of Kevlar–carbon hybrid laminates. Three eight-ply laminate configurations (V1, V2, and V3) were manufactured through distinct technological routes: fully prepreg-based hot pressing,
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The present study investigates the combined influence of manufacturing route and material configuration on the mechanical, elastic, viscoelastic, and impact behavior of Kevlar–carbon hybrid laminates. Three eight-ply laminate configurations (V1, V2, and V3) were manufactured through distinct technological routes: fully prepreg-based hot pressing, Kevlar-prepreg/dry-carbon hand lay-up followed by vacuum curing, and multi-stage hybrid consolidation combining repeated hot pressing with subsequent vacuum curing. The experimental characterization included tensile tests according to ASTM D3039, compression tests according to ASTM D695, determination of Young’s modulus from extensometer measurements and Poisson’s ratio using strain-gauge instrumentation, dynamic mechanical analysis (DMA), and low-velocity impact tests under controlled energy conditions. The novelty of this work consists in the integrated process–configuration–property comparison of these Kevlar–carbon hybrid routes within the same experimental framework, rather than in a generic demonstration that manufacturing affects composite laminates. The V1 laminate exhibited the highest strength-related performance, reaching an average tensile strength of 335.88 MPa and a compressive strength of 165.85 MPa, and it also showed the highest DMA storage modulus at 30 °C, E’ = 53.42 GPa. The V2 laminate presented lower tensile performance but the most pronounced damping response, with the highest tanδ peak value. The Young’s modulus determined from the extensometer measurements was 29.26 ± 1.45 GPa for V1, 26.10 ± 0.22 GPa for V2, and 29.52 ± 1.27 GPa for V3, indicating comparable longitudinal stiffness for the V1 and V3 laminates. The results indicate that the measured behavior is governed by the combined effects of reinforcement form, matrix/resin arrangement, consolidation route, and laminate architecture. Direct quantification of laminate compaction, fiber volume fraction, and void content was outside the scope of the present experimental campaign and is identified as a necessary step for future validation.
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(This article belongs to the Section Carbon Materials and Carbon Allotropes)
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Open AccessArticle
Preparation and Sorption Properties of Graphene Oxide and Melamine Composite Aerogels
by
S. A. Baskakov, Yu. V. Baskakova, A. V. Zharkovskaya, D. A. Chernyaev, E. N. Kabachkov, M. V. Zhidkov and Y. M. Shulga
C 2026, 12(3), 59; https://doi.org/10.3390/c12030059 - 13 Jul 2026
Abstract
In this study, composite aerogels based on graphene oxide (GO) and melamine (MM), obtained by freeze-drying of hydrogels after ultrasonic treatment of aqueous suspensions, have been systematically studied for the first time. It was shown that the addition of melamine leads to an
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In this study, composite aerogels based on graphene oxide (GO) and melamine (MM), obtained by freeze-drying of hydrogels after ultrasonic treatment of aqueous suspensions, have been systematically studied for the first time. It was shown that the addition of melamine leads to an increase in the aerogel density from 12 to 22 mg/cm3, a change in its color, and the formation of a structure reminiscent of nacre. Using IR spectroscopy, Raman scattering, TGA, and DSC, it was established that during synthesis, partial reduction of GO, hydrolysis of sulfate groups, and strong intermolecular (including possible covalent) interactions between the components occur. The exothermic peak for GO aerogel (ΔH ~1480 J/g, ~220 °C) shifts to a lower temperature region in the composite. MM/GO composite aerogels demonstrate record sorption capacity for organic solvents (up to 86 g/g) and mineral-oil (66 g/g), significantly surpassing known analogs. A key limitation was identified—the leaching of melamine by water, which reduces water sorption by 15 times after the first cycle. The obtained materials can be considered promising for eliminating spills of organic liquids and petroleum products.
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(This article belongs to the Section Carbon Materials and Carbon Allotropes)
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Valorization of Vigna trilobata Rind Waste into Activated Carbon for Efficient Iron Removal from Aqueous Solutions
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Vamsee Krishna Kodali, Randhi Uma Devi, K. Sri Lakshmi, Damaraju Lakshmi Lavanya and Bala chandu Koya
C 2026, 12(3), 58; https://doi.org/10.3390/c12030058 - 9 Jul 2026
Abstract
Iron (Fe) contamination of water sources has become an increasing environmental concern, creating the need for effective, environmentally friendly, and cost-effective technologies for Fe(III) removal from aqueous systems. In the present work, the possibility of using the sulfuric acid-activated carbon made of Vigna
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Iron (Fe) contamination of water sources has become an increasing environmental concern, creating the need for effective, environmentally friendly, and cost-effective technologies for Fe(III) removal from aqueous systems. In the present work, the possibility of using the sulfuric acid-activated carbon made of Vigna trilobata rind waste for treating water contaminated with Fe ions was explored. The characteristics of the synthesized material were identified by physical, chemical, and spectroscopic methods, and its Fe ion sorption efficiency was studied experimentally in batch mode under various conditions. Equilibrium, kinetics, and thermodynamics of Fe ion removal by the prepared adsorbent were determined. The obtained adsorbent had a BET surface area of 20.55 m2 g−1 and showed high experimental adsorption capacity with the highest observed uptake of 19.81 mg g−1. Based on the experimental results, the equilibrium data could be best described by the Langmuir equation (R2 = 0.978). Kinetic analysis showed that the rate-limiting step in Fe ion sorption was intraparticle diffusion (R2 = 0.921). Thermodynamic calculations indicated that the adsorption process occurred spontaneously (ΔG° = −4.31 to −6.53 kJ mol−1) and endothermically (ΔH° = +7.11 kJ mol−1). A comparative analysis showed that the sorption capacity of the studied adsorbent corresponded to that reported for the analogous materials produced from other biomasses.
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(This article belongs to the Section Carbon Materials and Carbon Allotropes)
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Open AccessReview
Carbon-Based Microfluidic Sensors for Water Monitoring
by
Guihe Li and Jia Yao
C 2026, 12(3), 57; https://doi.org/10.3390/c12030057 - 7 Jul 2026
Abstract
Carbon-based materials, including graphene, carbon nanotubes, laser-induced graphene, and pyrolyzed glassy carbon, are widely used in sensing applications due to their high conductivity, large surface area, and tunable surface chemistry. Meanwhile, microfluidic systems enable precise fluid handling, reduced sample consumption, and enhanced analytical
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Carbon-based materials, including graphene, carbon nanotubes, laser-induced graphene, and pyrolyzed glassy carbon, are widely used in sensing applications due to their high conductivity, large surface area, and tunable surface chemistry. Meanwhile, microfluidic systems enable precise fluid handling, reduced sample consumption, and enhanced analytical performance through improved mass transport and device miniaturization. The integration of carbon-based materials with microfluidic platforms has enabled the development of compact, portable, and highly sensitive devices for water monitoring. This review summarizes recent advances in carbon-based microfluidic sensors for water monitoring applications. Key carbon materials and their sensing mechanisms, particularly electrochemical transduction, are discussed. Various microfluidic integration strategies, including paper-based devices, polymer-based devices, MEMS-based systems, and flexible platforms, are highlighted, with emphasis on mass transport enhancement and overall system performance. Representative recent advances in carbon-based microfluidic sensors for water monitoring, including the detection of heavy metal ions, nutrients, and emerging contaminants, are reviewed. Finally, challenges related to scalable manufacturing, long-term operational stability, biofouling/surface fouling, and reproducible system integration are discussed, together with future perspectives on intelligent carbon-based microfluidic platforms featuring AI-assisted analytics, sense-response functionality, and self-healing and dynamic antifouling capabilities for water monitoring. These advances are expected to enable real-time, low-cost, and field-deployable water monitoring systems for environmental protection and public health management. Overall, this review highlights the critical role of integrating carbon-based sensing materials with microfluidic engineering in advancing next-generation water monitoring technologies.
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(This article belongs to the Special Issue Carbons for Health and Environmental Protection (2nd Edition))
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Biochar in Anaerobic Digestion: Part 2—Laser-Induced Breakdown Spectroscopy and Ultimate Analysis for Prediction of Biochar Higher Heating Value
by
Abdullah Al Saadi, Nour EI Houda Chaher, Hans Korte, Abdallah Nassour, Michael Nelles and Jan Sprafke
C 2026, 12(3), 56; https://doi.org/10.3390/c12030056 - 30 Jun 2026
Abstract
Reliable estimation of biochar’s calorific value is essential for optimizing its use as a renewable energy source. Traditional bomb calorimetry provides accurate measurements but is hindered by its destructive, time-consuming nature, limiting the high-throughput screening capabilities needed for large-scale deployment. In this study,
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Reliable estimation of biochar’s calorific value is essential for optimizing its use as a renewable energy source. Traditional bomb calorimetry provides accurate measurements but is hindered by its destructive, time-consuming nature, limiting the high-throughput screening capabilities needed for large-scale deployment. In this study, an innovative, non-destructive approach utilizing laser-induced breakdown spectroscopy (LIBS) combined with advanced multivariate analysis is presented for predicting the Higher Heating Value (HHV) of biochar derived from pine and beech biomass. The developed empirical model incorporates spectral signatures of key elements: carbon, hydrogen, nitrogen, sulfur, and oxygen. Model validation using 36 independent biochar samples revealed a statistically significant correlation between experimentally measured and LIBS-predicted HHVs (p-value = 0.045, t-statistic = 2.08). The developed model yielded a mean absolute error (MAE) of 1.33 MJ kg−1 and a root mean square error (RMSE) of 1.72 MJ kg−1. The findings demonstrate the feasibility of using LIBS-derived elemental data for rapid HHV estimation and provide a basis for further model refinement through the inclusion of additional biochar types and calibration datasets. The model effectively captures the complex nonlinear relationships between spectral features and energy content, addressing the heterogeneity inherent in biochar matrices. These findings highlight LIBS’s potential as a rapid, scalable, and environmentally sustainable tool for real-time biochar evaluation. Implementing this approach could significantly accelerate biomass resource assessment, optimize bioenergy production, and advance sustainable energy management strategies aligned with global environmental goals.
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(This article belongs to the Section Carbon Materials and Carbon Allotropes)
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Dislocation Reactions in a Crystal of Soft Particles in the Form of a Transversely Compressed Bundle of Carbon Nanotubes
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Olga V. Andrukhova, Andrey A. Ovcharov, Daria A. Durasova, Vladimir A. Bryzgalov, Arseny M. Kazakov, Marat A. Ilgamov, Elena A. Korznikova and Sergey V. Dmitriev
C 2026, 12(3), 55; https://doi.org/10.3390/c12030055 - 29 Jun 2026
Abstract
Properties of defects in crystals composed of soft particles, such as colloids, differ markedly from those in metals. In this work, dislocation reactions in a bundle of carbon nanotubes (CNTs) are investigated using relaxational molecular dynamics. The problem is reduced to a two-dimensional
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Properties of defects in crystals composed of soft particles, such as colloids, differ markedly from those in metals. In this work, dislocation reactions in a bundle of carbon nanotubes (CNTs) are investigated using relaxational molecular dynamics. The problem is reduced to a two-dimensional model, where the strain state of the CNT bundle is fully determined by the cross-sectional shapes of the nanotubes arranged in a close-packed triangular lattice. A pair of edge dislocations with opposite topological charges is introduced into an uniaxially compressed bundle, and their relaxational dynamics are analyzed as a function of the distance d between the parallel planes along which the dislocations glide. When the dislocations move in the same plane (d = 0), they annihilate, restoring a defect-free structure. For negative distances (d < 0), their interaction results in the formation of a vacancy (d = −1), a bivacancy (d = −2), extended voidions (d = −3, −4), or dislocation dipoles (d < −4). In contrast to metals, vacancy clusters containing more than two missing particles in CNT bundles relax into extended voidions. For positive distances (d > 0), the dislocation reaction generates interstitial-type defects in the form of crowdions, which at sufficiently large separations (d > 4) can also be interpreted as dislocation dipoles. In most cases, except for d = 0 and d = 1, dislocation glide enables complete relaxation of the initial shear strain, even in the presence of defects. However, for d = 0 and d = 1, dislocation annihilation or immobilization limits plastic deformation, resulting in only partial stress relaxation. The observed effects are due to the elliptization of the cross-sections of soft carbon nanotubes in the cores of defects. These findings highlight significant differences in defect behavior between crystals of deformable particles and conventional metallic systems.
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(This article belongs to the Section Carbon Materials and Carbon Allotropes)
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Open AccessReview
Recycling of Petroleum-Based Lubricants into High-Value Petrochemicals and Carbon-Based Materials
by
Sandugash Tanirbergenova, Dildara Tugelbayeva, Nurzhamal Zhylybayeva, Aizat Aitugan, Arailym Akimbek, Kairat Tazhu, Gulya Moldazhanova and Zulkhair Mansurov
C 2026, 12(3), 54; https://doi.org/10.3390/c12030054 - 25 Jun 2026
Abstract
Waste lubricating oils (WLOs) represent a major stream of hazardous petroleum-based residues, with global generation exceeding 24 million tons annually. Improper disposal of WLOs poses risks to soil, water, and air quality, while their chemical composition makes them a potential secondary resource within
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Waste lubricating oils (WLOs) represent a major stream of hazardous petroleum-based residues, with global generation exceeding 24 million tons annually. Improper disposal of WLOs poses risks to soil, water, and air quality, while their chemical composition makes them a potential secondary resource within circular economy frameworks. This review summarizes conventional, advanced, and emerging technologies reported for the recycling and valorization of WLOs into high-value petrochemicals and carbon-based materials. Established processes such as acid–clay treatment, solvent extraction, and vacuum distillation are discussed together with more recent approaches, including catalytic upgrading, hydrotreatment, membrane separation, and thermochemical conversion methods such as pyrolysis and catalytic cracking. Reported data on process performance, environmental considerations, techno-economic indicators, and life cycle assessment outcomes are comparatively analyzed to outline current trends, technical challenges, and future development directions in WLO recycling. Particular attention is given to thermochemical pathways capable of generating carbonaceous materials, including carbon black, porous carbons, and functional carbon nanostructures with potential applications in adsorption, catalysis, electrochemical systems, and tribological formulations. Hybrid and integrated process configurations described in the literature are highlighted for their potential to improve recovery efficiency, enhance product quality, and reduce environmental burdens. In addition, recent life cycle assessment (LCA) and techno-economic analysis (TEA) studies are reviewed to provide insight into the environmental and economic implications of advanced re-refining systems. Overall, the reviewed literature indicates that WLO recycling represents not only an important element of sustainable lubricant management but also a promising waste-to-carbon strategy for the production of value-added carbon-based materials and petrochemical products.
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(This article belongs to the Special Issue Advances in Carbon-Based Materials)
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Assessment of Production Methods and Locations for CO2 Storage in Seafloor Environment
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Muhammad Towhidul Islam, Vincent Nana Boah Amponsah and Boyun Guo
C 2026, 12(2), 53; https://doi.org/10.3390/c12020053 - 22 Jun 2026
Abstract
Disposing of carbon dioxide (CO2) in the seafloor environment in its hydrate form provides an efficient means of CO2 storage in virtually unlimited quantity. The process requires that the in situ condition be above the hydrate-forming pressure and below the
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Disposing of carbon dioxide (CO2) in the seafloor environment in its hydrate form provides an efficient means of CO2 storage in virtually unlimited quantity. The process requires that the in situ condition be above the hydrate-forming pressure and below the hydrate-forming temperature and that the bulk CO2 hydrates have densities greater than seawater density for gravitational stability. The objectives of this study are (1) to find an efficient method for generating stable CO2 hydrates, (2) to identify the required equipment for efficient production of CO2 hydrates, and (3) to identify the required water depth in various seawater environments for CO2 injection. The first objective was achieved using a windowed reactor to observe the floating and settling behavior of generated CO2 hydrates. CO2 injection into the chilly water phase and water injection into the cold CO2 phase were both investigated at various pressures and temperatures. CO2 injection into the chilly water phase was found to generate bulk CO2 hydrates of density less than that of water due to the excess CO2 trapped in the bulk hydrates. Water injection into the cold CO2 phase was found to generate bulk CO2 hydrates of density greater than that of water due to the excess water trapped in the bulk hydrates. The second objective was achieved by designing a complete set of equipment to be installed on a ship with an open-bottom reactor assembly attached to the ship. The third objective was achieved by cross-plotting the hydrate-forming pressure curve versus the seawater hydrostatic pressure curve for seven seas and the Arctic Ocean. Results show that the minimum required seawater depth varies from 120 m in the Arctic Ocean to 650 m in the Mediterranean Sea environment.
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(This article belongs to the Section Carbon Cycle, Capture and Storage)
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Microwave-Assisted N,S Co-Doped Reduced Graphene Oxide for Eco-Friendly Environmental Monitoring of Nitrobenzene
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Prathingara Subramanian, Tharini Jeyapragasam, Kandasamy Muthusamy, Vinitha Mariyappan and Rasu Ramachandran
C 2026, 12(2), 52; https://doi.org/10.3390/c12020052 - 17 Jun 2026
Cited by 1
Abstract
A nitrogen/sulfur co-doped reduced graphene oxide (N,S-RGO) material was rationally prepared via a modified Hummers method followed by microwave-assisted reduction. The resulting material was uniformly deposited onto a glassy carbon electrode (GCE) to fabricate an electrochemical sensor for nitrobenzene (NB) detection. The prepared
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A nitrogen/sulfur co-doped reduced graphene oxide (N,S-RGO) material was rationally prepared via a modified Hummers method followed by microwave-assisted reduction. The resulting material was uniformly deposited onto a glassy carbon electrode (GCE) to fabricate an electrochemical sensor for nitrobenzene (NB) detection. The prepared N,S-RGO material was characterized in detail using Fourier-transform infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy, confirming the successful incorporation of heteroatoms. Furthermore, electrochemical studies, including cyclic voltammetry (CV) and linear sweep voltammetry (LSV), revealed the enhanced electrical conductivity of the material. The fabricated N,S-RGO/GCE sensor exhibited remarkable electroanalytical performance, achieving a low detection limit (LOD) of 7 nM within a linear concentration range of 0.05 to 147 µM. The enhanced sensing performance is attributed to the synergistic effect of nitrogen and sulfur doping, which improves electron transfer kinetics and abundant active sites for NB reduction. Furthermore, the sensor demonstrated outstanding selectivity toward NB in the presence of common interfering substances. Its practical applicability was confirmed through the successful detection of NB in environmental water samples, yielding convincing recovery rates. These results highlight the potential of the N,S-RGO/GCE platform as an efficient and reliable electrochemical sensor for environmental monitoring of NB contamination.
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(This article belongs to the Topic Environmental Pollutant Management and Control)
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Surface-Integrated Hydrogen Sensing Using ZnFe2O4–CNT Composite Coatings on Cement-Based Materials with Data-Driven Concentration Prediction
by
Mohammadmahdi Abedi, Zivar Azmoodeh and Eloi Figueiredo
C 2026, 12(2), 51; https://doi.org/10.3390/c12020051 - 9 Jun 2026
Abstract
Transforming existing structural surfaces into sensing interfaces offers a promising route for scalable hydrogen monitoring in hydrogen-handling facilities, where leakage poses significant safety risks, addressing the limitations of conventional point-based sensors. In this study, a surface-integrated ZnFe2O4–CNT (ZFC) composite
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Transforming existing structural surfaces into sensing interfaces offers a promising route for scalable hydrogen monitoring in hydrogen-handling facilities, where leakage poses significant safety risks, addressing the limitations of conventional point-based sensors. In this study, a surface-integrated ZnFe2O4–CNT (ZFC) composite coating is developed as a potentially retrofit-compatible sensing solution to enable hydrogen sensing directly on cementitious materials, combining material-level functionality with data-driven concentration prediction. The ZFC composite was synthesized via a hydrothermal method followed by CNT functionalization and composite formation, and was then applied onto cement-based substrates using a thickness-controlled coating approach. Structural and morphological characterization (XRD, FESEM, TEM, BET) confirmed the formation of a hierarchical, porous architecture, while hydrogen sensing performance was evaluated under controlled thermo-hygrometric conditions (24–72 °C, 32–87% RH) at 10,000 ppm H2. The sensor exhibited stable and reversible responses, with optimal performance at 39–52 °C and a minimum response time of 18 s. An XGBoost model enabled accurate prediction of hydrogen concentration, achieving R2 ≈ 0.92 and RMSE ≈ 820 ppm under dynamic exposure. These results demonstrate that coupling redox-active oxide surfaces with conductive CNT networks enables effective surface-based chemiresistive sensing under realistic conditions. The proposed system transforms conventional cementitious materials into smart, surface-integrated hydrogen sensing systems, offering a scalable and retrofit-compatible approach for real-time monitoring in hydrogen-related infrastructure.
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(This article belongs to the Section Carbon Materials and Carbon Allotropes)
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Open AccessArticle
Effects of Co-Solvent and Polymer Composition in Gel Electrolytes on the Performance of Paper Dye-Sensitized Solar Cells
by
Yi Kou and Takahide Oya
C 2026, 12(2), 50; https://doi.org/10.3390/c12020050 - 4 Jun 2026
Abstract
In this study, we investigated how co-solvent and polymer combinations affect the performance of dye-sensitized solar cells (DSSCs) using TiO2- and ZnO-modified carbon nanotube (CNT) composite papers as photoelectrodes. Co-solvents such as N,N-dimethylformamide (DMF) and ethylene glycol (EG) were incorporated into
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In this study, we investigated how co-solvent and polymer combinations affect the performance of dye-sensitized solar cells (DSSCs) using TiO2- and ZnO-modified carbon nanotube (CNT) composite papers as photoelectrodes. Co-solvents such as N,N-dimethylformamide (DMF) and ethylene glycol (EG) were incorporated into polyethylene glycol (PEG)- and poly(ethylene oxide) (PEO)-based gel electrolytes to increase the amount of dissolved I2/KI redox species and evaluate their influence on the wettability of the electrolyte on CNT composite paper electrodes. PEG-based electrolytes containing DMF or EG improved the fill factor (FF) and power conversion efficiency (PCE) relative to the baseline formulation, with the EG–PEG electrolyte achieving the best single-device PCE of 15.58 × 10−3% using the CNT/ZnO composite paper. Replacing PEG with PEO or using PEG + PEO blends led to reduced performance, possibly because the modified polymer composition affected electrolyte wetting, spreading behavior, and penetration into the porous electrode. These results suggest that the wettability and viscosity-related behavior of gel electrolytes are important empirical factors associated with the performance of flexible paper DSSCs, and provide practical guidance for the design of paper-based photovoltaic devices.
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(This article belongs to the Special Issue Optical and Electronic Innovations in Carbon Nanotubes)
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Lignin Valorization via Microwave Processing: Conversion to Porous Hydrophilic Carbon Materials
by
Larissa Giorgetti Mendes, Paloma Elias da Silva Pellegrini, Eduardo de Souza Esperança, Silvia Vaz Guerra Nista and Stanislav Moshkalev
C 2026, 12(2), 49; https://doi.org/10.3390/c12020049 - 31 May 2026
Abstract
Millions of tons of lignin waste are generated annually by the pulp and paper industries and by biofuel production. Current strategies for lignin valorization, biochars and hydrogels, often rely on time-costly and pollutant-generating processes and therefore fail to meet sustainability requirements nor are
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Millions of tons of lignin waste are generated annually by the pulp and paper industries and by biofuel production. Current strategies for lignin valorization, biochars and hydrogels, often rely on time-costly and pollutant-generating processes and therefore fail to meet sustainability requirements nor are economically efficient. In this work, we address the challenge of transforming lignin into a valued-added material. We propose using microwave processing to convert lignin into a functional material that is carbon-rich, structured, hydrophilic, and highly porous. Unlike conventional methods, this process is rapid, occurring in approximately 30 s under normal conditions. It induces graphitization and up to a sixfold volumetric expansion of the lignin precursor sample, leading to the formation of a stable carbon material with high porosity in the form of capsules. The resulting material exhibits strong hydrophilicity, absorbing up to 90% of its volume in water within minutes while enabling controlled release over periods of up to 24 h. This unique combination of ultrafast processing, high water uptake capacity, and controlled-release performance positions the material as a promising alternative to the valorization of lignin. Its properties make it particularly suitable for water management applications in agriculture and urban environments.
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(This article belongs to the Topic Functional Carbon-Based Materials and Systems for Energy and Environmental Applications)
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Physicochemical Properties of Pristine and Pyrolyzed CNO Synthesized via Wick Pyrolysis
by
Abirami Srinivasan, Avanottingal Bhaskaran Prasanth, C. N. Shyam Kumar and Amrtha Bhide
C 2026, 12(2), 48; https://doi.org/10.3390/c12020048 - 29 May 2026
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Carbon nano-onions (CNOs) were synthesized at ambient conditions using the wick-pyrolysis technique with ghee as a precursor. A high-purity copper substrate produced unique CNOs, differing from those obtained with other metals. To purify the nanoparticles, they underwent treatment with a solvent mixture of
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Carbon nano-onions (CNOs) were synthesized at ambient conditions using the wick-pyrolysis technique with ghee as a precursor. A high-purity copper substrate produced unique CNOs, differing from those obtained with other metals. To purify the nanoparticles, they underwent treatment with a solvent mixture of acetone and deionized water or were pyrolyzed at 1000 °C under nitrogen without a catalyst. Various characterization techniques, including X-ray diffraction (XRD), Field Emission Scanning Electron Microscopy (FE-SEM), High-Resolution Transmission Electron Microscopy (HR-TEM), and Raman Spectroscopy, confirmed the successful formation of CNOs. Energy Dispersive Spectroscopy (EDS) and Elemental analysis (CHN) indicated the presence of oxygen in treated CNOs. X-ray photoelectron spectroscopy (XPS) revealed binding energies linked to C-O and C=O bonds. The average particle size was found to be 30–50 nm, with some agglomeration in pyrolyzed samples. A significant increase in surface area from 79.7 m2/g to 261.8 m2/g was observed, along with changes in pore radius and volume via Brunauer–Emmett–Teller (BET) analysis. Water contact angles on the CNO surface were measured at 125° and 138°, indicating hydrophobicity. Electrochemical tests on CNO-based composite electrodes yielded a specific capacitance of 109.7 F/g with 96% capacity retention over 5000 cycles.
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Open AccessArticle
Hydrothermal Synthesis of Carbon Microspheres from Lignocellulosic Bio-Oil
by
Galina Dobele, Ance Plavniece, Kristine Meile, Kalvis Liepins, Oskars Bikovens, Vilhelmine Jurkjane and Aivars Zhurinsh
C 2026, 12(2), 47; https://doi.org/10.3390/c12020047 - 27 May 2026
Abstract
Biomass valorization into carbon-rich materials has attracted increasing attention as a sustainable alternative to fossil-based resources. This work is devoted to the study of hydrothermal carbonization (HTC) of spruce lignocellulose liquid pyrolysis products (the target product of the pyrolysis is levoglucosan)—bio-oil (B). In
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Biomass valorization into carbon-rich materials has attracted increasing attention as a sustainable alternative to fossil-based resources. This work is devoted to the study of hydrothermal carbonization (HTC) of spruce lignocellulose liquid pyrolysis products (the target product of the pyrolysis is levoglucosan)—bio-oil (B). In addition, the fractionated B compounds, including the phenol-enriched fraction remaining after anhydrosugar removal, were evaluated as potential precursors for hydrochar production. Hydrochars were produced at 200, 250, and 300 °C and characterized using SEM, revealing that spherical morphology agglomerates can also be obtained from the phenol-enriched fraction. The chemical composition and structural evolution of the hydrochars were investigated by Py-GC/MS, elemental analysis, and FTIR, demonstrating the significant influence of both precursor composition and carbonization temperature on hydrochar chemistry. In addition, the organic compounds in the process water were analyzed using UHPLC and complementary chemical analysis. The results show that the chemical composition of the precursor strongly influences the yield, morphology, and chemical composition of the obtained hydrochar.
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(This article belongs to the Section Carbon Materials and Carbon Allotropes)
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Open AccessReview
Carbon Quantum Dots as Emerging Antibacterial Nanomaterials: Strategies to Enhance Their Activity
by
Hong Yin, Wenjing Chen, August Bratovic, Rachel W. Li and Ivan Cole
C 2026, 12(2), 46; https://doi.org/10.3390/c12020046 - 27 May 2026
Abstract
Carbon quantum dots (CQDs) exhibit multiple antibacterial mechanisms, making them more effective than conventional antibiotics, which typically act through a single mode of action. These mechanisms include membrane disruption, biofilm inhibition, reactive oxygen species (ROS) generation, and photodynamic (PDT) or photothermal (PTT) effects
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Carbon quantum dots (CQDs) exhibit multiple antibacterial mechanisms, making them more effective than conventional antibiotics, which typically act through a single mode of action. These mechanisms include membrane disruption, biofilm inhibition, reactive oxygen species (ROS) generation, and photodynamic (PDT) or photothermal (PTT) effects under light irradiation. Extensive research has been conducted to reinforce these mechanisms and improve the antibacterial performance of CQDs, aiming to reduce required CQD dosages and combat bacterial resistance. This review systematically summarizes structural and functional design strategies reported since 2020. We categorized these strategies into selecting antibacterial molecules as precursors, controlling particle size, surface modification, doping with non-metal and metal elements, and forming functional composites to enable light activation, synergetic effects, and multifunctionality. For each category, we provide representative CQD examples, in terms of their preparation, physicochemical properties contributing to antibacterial performance, and possible structure–activity relationships. Finally, the review highlights limitations and proposes future research directions for developing antibacterial CQDs for clinical translation.
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(This article belongs to the Section Carbon Materials and Carbon Allotropes)
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Open AccessArticle
Effects of Feedstock Type and Pyrolysis Duration on Functional Properties of Biomass-Derived Charred Materials Under Low-Temperature Pyrolysis
by
Zonghui Chu, Tsuneyoshi Endo, Tsugiyuki Masunaga, Eiji Nishihara and Sadahiro Yamamoto
C 2026, 12(2), 45; https://doi.org/10.3390/c12020045 - 25 May 2026
Abstract
Low-temperature pyrolysis around 250 °C represents a mild carbonization that differs from conventional high-temperature biochar production, and the role of pyrolysis duration under mild thermal conditions remains insufficiently understood. In this study, plant residues, including rice straw, sorghum leaves and stems, barley straw,
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Low-temperature pyrolysis around 250 °C represents a mild carbonization that differs from conventional high-temperature biochar production, and the role of pyrolysis duration under mild thermal conditions remains insufficiently understood. In this study, plant residues, including rice straw, sorghum leaves and stems, barley straw, and mixed woodchips, were converted into charred materials under low-temperature pyrolysis at 250 °C (4 h, 12 h) and compared with those produced at 500 °C (4 h). Pyrolysis at 250 °C (4 h) resulted in higher solid yields (51.9–72.8%) and higher recovery of carbon and nitrogen, whereas yields declined to 27.2–31.6% at 500 °C. Materials produced at 250 °C preserved abundant oxygen-containing functional groups, exhibited lower pH, and showed significantly higher cation exchange capacity (up to 93.68–119.91 cmolc/kg at 12 h). Prolonged treatment at 250 °C enhanced humification, increasing the carbon extracted from humic acid by 25.3–237.9%, whereas humic substances were largely decomposed at 500 °C. Structural analyses indicated that low-temperature chars maintained reactive surface chemistry, while high-temperature chars showed greater aromaticity and porosity, particularly for wood-derived materials (378.5 m2/g). Overall, low-temperature pyrolysis produces functionally active carbon materials suitable for saline-sodic soil amendment and nutrient management, whereas 500 °C pyrolysis generates more aromatic and porous materials better suited for long-term carbon stability and physical soil conditioning.
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(This article belongs to the Section Carbon Cycle, Capture and Storage)
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Open AccessArticle
Response Surface Optimization of Lead Sorption by Pinus roxburghii Cone-Derived Activated Carbon: Performance Assessment and Optimization
by
Aditi, Dharmendra, Aditya Thakur, Chetna Tewari and Sumit Kumar
C 2026, 12(2), 44; https://doi.org/10.3390/c12020044 - 25 May 2026
Abstract
The pervasive issue of lead contamination in water systems necessitates the development of advanced and sustainable remediation methodologies. Powdered activated carbon synthesized from Pinus roxburghii has been meticulously evaluated as a high-performance capture medium to remove sequestration of lead ions from aqueous systems
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The pervasive issue of lead contamination in water systems necessitates the development of advanced and sustainable remediation methodologies. Powdered activated carbon synthesized from Pinus roxburghii has been meticulously evaluated as a high-performance capture medium to remove sequestration of lead ions from aqueous systems through batch adsorption studies. These adsorption dynamics were optimized by Response Surface Methodology integrated with Central Composite Design, enabling precise calibration of crucial influential factors such as pH, contact time, and adsorbent dosage. Morphological analysis conducted using Scanning Electron Microscopy confirmed a highly porous structure, while Fourier Transform Infrared Spectroscopy identified functional groups, such as hydroxyl groups coupled with carbonyl groups, which exhibit strong metal affinity. Under optimal conditions, a pH of 8.2, a time of 140 min, and an adsorbent dosage of 0.03 g/L resulted in a maximum lead removal efficiency of 99.86%. Validation trials substantiated the reproducibility of the process, yielding a marginally diminished efficiency of 98.62 ± 1.24%. The integration of RSM not only validated the statistical significance of the experimental outcomes but also reinforced the predictive accuracy. This study demonstrates the critical interplay of adsorption parameters and highlights the physicochemical properties of Pinus roxburghii-based activated carbon, emphasizing its potential for advanced water purification processes.
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(This article belongs to the Section Carbon Materials and Carbon Allotropes)
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Open AccessEditorial
Editorial for C—Journal of Carbon Research: 10th Anniversary Special Issue
by
Craig E. Banks
C 2026, 12(2), 43; https://doi.org/10.3390/c12020043 - 15 May 2026
Abstract
The 10th Anniversary Issue of C—Journal of Carbon Research has concluded with the publication of 21 high-quality papers [...]
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(This article belongs to the Special Issue 10th Anniversary of C — Journal of Carbon Research)
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