C | An Open Access Journal from MDPI

16 pages, 2472 KiB

Open AccessArticle

Green Synthesis of a Highly Active Ag/Activated Carbon Nanocomposite from Tamarind Seeds for Methyl Orange Removal

by Samah Daffalla, Nura Al Mousa, Hussain Ahmed, Jana Alsuwailem, Mustafa I. Almaghasla and Mohamed R. El-Aassar

C 2025, 11(2), 27; https://doi.org/10.3390/c11020027 - 17 Apr 2025

Abstract

This study investigated the enhanced adsorption capacity of a silver nanoparticle (AgNPs)-incorporated tamarind seed activated carbon nanocomposite (Ag/TSAC) for the elimination of methyl orange (MO) from aqueous solutions. The nanocomposite was analyzed using TGA, SEM, FTIR, and BET, revealing a mesoporous structure with [...] Read more.

This study investigated the enhanced adsorption capacity of a silver nanoparticle (AgNPs)-incorporated tamarind seed activated carbon nanocomposite (Ag/TSAC) for the elimination of methyl orange (MO) from aqueous solutions. The nanocomposite was analyzed using TGA, SEM, FTIR, and BET, revealing a mesoporous structure with a surface area of 54.92 m²/g. The results showed that the structure of tamarind seeds altered during pyrolysis, as shown by the loss of many functional groups and a weight decrease of 66.61% in the nanocomposite. The efficiency of the nanocomposite in eliminating MO was assessed by batch adsorption studies, which also examined the effects of solution pH, starting MO concentration, and nanocomposite dose. The best MO removal was seen at pH 2, indicating a positive electrostatic interaction between the dye and adsorbent. The results demonstrated that the Ag/TSAC nanocomposite significantly enhanced MO removal efficiency from 19% to 96% under optimal adsorptive conditions, due to the synergistic effect of the high surface area of activated carbon and the enhanced adsorption sites provided by the AgNPs. The study demonstrates the potential of Ag/activated carbon nanocomposite as a sustainable adsorbent for removing MO dye from wastewater using a second-order model and Langmuir model. Full article

(This article belongs to the Special Issue Carbon Functionalization: From Synthesis to Applications)

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12 pages, 19666 KiB

Open AccessArticle

Modulation of Giant Magnetoimpedance Effect in Co-Based Amorphous Wires by Carbon-Based Nanocoatings

by Zhen Yang, Jiabao Huang, Jingyuan Chen and Chong Lei

C 2025, 11(2), 26; https://doi.org/10.3390/c11020026 - 1 Apr 2025

Abstract

Co-based amorphous wires (Co-AWs) are functional materials renowned for their high impedance change rate in magnetic fields and a pronounced giant magnetoimpedance (GMI) effect. In this study, magnetron sputtering (MS) and dip-coating (DC) techniques were employed to fabricate carbon-based nanocoatings aimed at modulating [...] Read more.

Co-based amorphous wires (Co-AWs) are functional materials renowned for their high impedance change rate in magnetic fields and a pronounced giant magnetoimpedance (GMI) effect. In this study, magnetron sputtering (MS) and dip-coating (DC) techniques were employed to fabricate carbon-based nanocoatings aimed at modulating the GMI properties of Co-AWs. The magnetic properties and GMI responses of the composite Co-AWs with carbon-based coatings were comparatively analyzed. The results demonstrate that both methods effectively enhanced the GMI properties of the coated Co-AWs. The DC method emerged as a rapid and efficient approach for forming the coated film, achieving a modest enhancement in GMI performance (10% enhancement). In contrast, the MS technique proved more effective in improving the GMI effect, yielding superior results. Co-AWs coated via Ms exhibited smoother surfaces and reduced coercivity. Notably, the GMI effect increased with the thickness of the sputtered carbon coatings, reaching a maximum GMI effect of 522% (a remarkable 357% enhancement) and a sensitivity of 33.8%/Oe at a coating thickness of 334 nm. The observed trend in the GMI effect with carbon layer thickness corresponded closely to variations in transverse permeability, as determined by vibrating sample magnetometry (VSM). Furthermore, the carbon coating induced changes in the initial quenching stress on the surface of the Co-AWs, leading to alterations in impedance and a significant reduction in the characteristic frequency of the Co-AWs. Our findings provide valuable insights into the modulation of GMI properties in Co-AWs, paving the way for their optimized application in advanced magnetic sensor technologies. Full article

(This article belongs to the Section Carbon Materials and Carbon Allotropes)

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19 pages, 4792 KiB

Open AccessArticle

Conversion of Carbon Dioxide into Solar Fuels Using MgFe₂O₄ Thermochemical Redox Chemistry

by Rahul R. Bhosale

C 2025, 11(2), 25; https://doi.org/10.3390/c11020025 - 25 Mar 2025

Abstract

Transforming H₂O and CO₂ into solar fuels like syngas is crucial for future sustainable transportation fuel production. Therefore, the MgFe₂O₄/CO₂ splitting cycle was thermodynamically scrutinized to estimate its solar-to-fuel energy conversion efficiency in this investigation. [...] Read more.

Transforming H₂O and CO₂ into solar fuels like syngas is crucial for future sustainable transportation fuel production. Therefore, the MgFe₂O₄/CO₂ splitting cycle was thermodynamically scrutinized to estimate its solar-to-fuel energy conversion efficiency in this investigation. The thermodynamic data required to solve the modeling equations were obtained using the HSC Chemistry program. The reduction non-stoichiometry was assumed to be equal to 0.1 for all computations. One of the study’s primary goals was to examine the impact of the inert sweep gas’s molar flow rate on the process parameters related to the MgFe₂O₄/CDS cycle. Overall, it was understood that the effect of the inert sweep gas’s molar flow rate on the thermal reduction temperature was significant when it increased from 10 to 40 mol/s compared to the rise from 40 to 100 mol/s. The energy needed to reduce MgFe₂O₄ increased slightly due to the surge in the inert sweep gas’s molar flow rate. In contrast, the energy penalty for heating MgFe₂O_4-δred from the re-oxidation to thermal reduction temperature significantly decreased. Including gas-to-gas heat exchangers with a gas-to-gas heat recovery effectiveness equal to 0.5 helped reduce the energy demand for heating the inert sweep gas. Overall, although the rise in the inert sweep gas’s molar flow rate from 10 to 100 mol/s caused a drop in the thermal reduction temperature by 180 K, the total solar energy needed to drive the cycle was increased by 85.7 kW. Accordingly, the maximum solar-to-fuel energy conversion efficiency (13.1%) was recorded at an inert sweep gas molar flow rate of 10 mol/s, which decreased by 3.7% when it was increased to 100 mol/s. Full article

(This article belongs to the Section CO₂ Utilization and Conversion)

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18 pages, 21154 KiB

Open AccessArticle

Preparation of CCF/MWCNT-OH/Graphite/Resin Composite Bipolar Plates Using Bi-Directional Interfacial Modification and Study of Their Performance Improvement and the Mechanism of Their Interfacial Bonding Improvement

by Wenkai Li, Haodong Zeng and Zhiyong Xie

C 2025, 11(1), 24; https://doi.org/10.3390/c11010024 - 19 Mar 2025

Abstract

Composite bipolar plates are a new class of material bipolar plates for PEMFCs. However, their application is limited by problems such as the difficulty of balancing their strength/conductivity properties. In this paper, by using surface-modified carboxylated short-cut carbon fibers and hydroxylated carbon nanotubes [...] Read more.

Composite bipolar plates are a new class of material bipolar plates for PEMFCs. However, their application is limited by problems such as the difficulty of balancing their strength/conductivity properties. In this paper, by using surface-modified carboxylated short-cut carbon fibers and hydroxylated carbon nanotubes as well as PI resin, the interfacial bonding between the carbon-based filler and the resin is effectively improved under the premise of ensuring electrical conductivity, which enhances the flexural strength. The effect of the surface modification of the filler on the interfacial bonding between the filler and the PI resin is thoroughly investigated through molecular dynamics simulations. The mechanism for this improved bonding was also studied. Through the surface modification of the filler, the composite bipolar plates possessed a flexural strength of 49.06 MPa and a planar conductivity of 228.52 S/cm with the addition of 6% MWCNT-OH as well as 12% CCFs, which has the potential to be an optional substrate for composite bipolar plates. Full article

(This article belongs to the Special Issue Carbon-Based Polymer Composites: Synthesis, Processing, Characterization and Applications)

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8 pages, 2405 KiB

Open AccessCommunication

One-Pot Bottom-Up Synthesis of SiO₂ Quantum Dots and Reduced Graphene Oxide (rGO) Nanocomposite as Anode Materials in Lithium-Ion Batteries

by Sanjaya Brahma, Cheung-Yi Wang, Yi-Hsuan Huang, Wen-Feng Lin and Jow-Lay Huang

C 2025, 11(1), 23; https://doi.org/10.3390/c11010023 - 10 Mar 2025

Abstract

Here, crystalline SiO₂ quantum dots (QDs) of 3–5 nm size were grown within the layers of reduced graphene oxide (rGO) by a solution mode chemical growth process at a relatively low temperature (100 °C). The composite was applied as a negative electrode [...] Read more.

Here, crystalline SiO₂ quantum dots (QDs) of 3–5 nm size were grown within the layers of reduced graphene oxide (rGO) by a solution mode chemical growth process at a relatively low temperature (100 °C). The composite was applied as a negative electrode in a Li-ion half-cell battery and the electrochemical investigation confirmed a distinct first-cycle discharge/charge capacity (~865 mAhg⁻¹/387 @ 51 mAg⁻¹). The battery could retain a capacity of 296 mAhg⁻¹ after 60 charge/discharge cycles with 99% coulombic efficiency. Furthermore, at a high current rate of 1.02 Ag⁻¹, the battery was able to display an apparent rate capability (214.47 mAhg⁻¹), indicating the high chemical and mechanical stability of the composite at a high current rate. A structural analysis revealed clear distinct diffraction peaks of SiO₂ and high-resolution transmission electron microscopy images showed discrete atomic planes, thereby confirming the growth of crystalline SiO₂ QDs within the layers of rGO. Full article

(This article belongs to the Special Issue Micro/Nanofabrication of Carbon-Based Devices and Their Applications)

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18 pages, 3950 KiB

Open AccessArticle

Environmental Impacts and Adsorption Isotherms of Coconut Shell Activated Carbon: Effect of Acid Activation, Water, and Fuel

by Junaid Saleem, Zubair Khalid Baig Moghal, Furqan Tahir, Tareq Al-Ansari and Gordon McKay

C 2025, 11(1), 22; https://doi.org/10.3390/c11010022 - 10 Mar 2025

Abstract

Activated biomass has gained interest as an alternative to coal-based activated carbon (AC). This work investigates the environmental impact (EI) of coconut shell (CS)-derived AC as a substitute for non-renewable coal-based AC. The AC was produced in-house using tandem acid activation and pyrolysis, [...] Read more.

Activated biomass has gained interest as an alternative to coal-based activated carbon (AC). This work investigates the environmental impact (EI) of coconut shell (CS)-derived AC as a substitute for non-renewable coal-based AC. The AC was produced in-house using tandem acid activation and pyrolysis, employing two activation pathways: sulfuric acid (H₂SO₄) and phosphoric acid (H₃PO₄). This study further investigates the impact of activation routes, fuel types, and water sources on environmental outcomes. This evaluation focuses on six key impacts: climate change, fossil depletion, freshwater ecotoxicity, freshwater eutrophication, land use, and energy net. The H₂SO₄ activation pathway is more favorable in terms of EI due to its lower net energy requirement (27.2 MJ) and reduced carbon emissions (1.2 kg CO₂ eq.). However, it requires 4.7 kg of AC to adsorb 1 kg of dye, whereas the H₃PO₄ pathway requires only 4.3 kg. Therefore, while the H₃PO₄ pathway may be preferred for applications needing higher adsorption capacities, the H₂SO₄ pathway offers a more environmentally benign option, highlighting the trade-offs in selecting an activation method for AC production. Additionally, this study highlights that CS-derived AC offers substantial energy savings of 78%, alongside a 75% reduction in carbon emissions and an 80% decrease in fossil depletion compared to coal-based AC. Overall, the synthesized AC shows promise as a sustainable alternative to coal-based counterparts. Full article

(This article belongs to the Section Carbon Materials and Carbon Allotropes)

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5 pages, 228 KiB

Open AccessEditorial

Nanocarbon-Based Composites and Their Thermal, Electrical, and Mechanical Properties

by Gil Gonçalves

C 2025, 11(1), 21; https://doi.org/10.3390/c11010021 - 8 Mar 2025

Abstract

Carbon materials have played a pivotal role in humanity’s progress since ancient times [...] Full article

(This article belongs to the Collection Nanocarbon-Based Composites and Their Thermal, Electrical, and Mechanical Properties)

21 pages, 5290 KiB

Open AccessArticle

Historical Drivers and Reduction Paths of CO₂ Emissions in Jiangsu’s Cement Industry

by Kuanghan Sun, Jian Sun, Changsheng Bu, Long Jiang and Chuanwen Zhao

C 2025, 11(1), 20; https://doi.org/10.3390/c11010020 - 5 Mar 2025

Abstract

With global climate challenges intensifying, the cement industry, as a major CO₂ emitter, has attracted significant attention regarding its emission reduction potential and strategies. Advanced economies like the European Union use carbon pricing to spur innovation, while emerging countries focus on incremental [...] Read more.

With global climate challenges intensifying, the cement industry, as a major CO₂ emitter, has attracted significant attention regarding its emission reduction potential and strategies. Advanced economies like the European Union use carbon pricing to spur innovation, while emerging countries focus on incremental solutions, such as fuel substitution. Combining LMDI decomposition and the LEAP model, this study examines Jiangsu Province as a test bed for China’s decarbonization strategy, a highly efficient region with carbon intensity 8% lower than the national average. Historical analysis identifies carbon intensity, energy mix, energy intensity, output scale, and economic effects as key drivers of emission changes. Specifically, the reduction in cement production, real estate contraction, lower housing construction, and reduced production capacity are the main factors curbing emissions. Under an integrated technology strategy—including energy efficiency, fuel and clinker substitution, and CCS—CO₂ emissions from Jiangsu’s cement sector are projected to decrease to 17.28 million tons and 10.9 million tons by 2060 under high- and low-demand scenarios, respectively. Clinker substitution is the most significant CO₂ reduction technology, contributing about 60%, while energy efficiency gains contribute only 3.4%. Despite the full deployment of existing reduction methods, Jiangsu’s cement industry is expected to face an emissions gap of approximately 10 million tons to achieve carbon neutrality by 2060, highlighting the need for innovative emission reduction technologies or carbon trading to meet carbon neutrality goals. Full article

(This article belongs to the Section Carbon Cycle, Capture and Storage)

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22 pages, 10051 KiB

Open AccessArticle

Reuse of Activated Carbons from Filters for Water Treatment Derived from the Steam Cycle of a Nuclear Power Plant

by Beatriz Ledesma Cano, Eva M. Rodríguez, Juan Félix González González and Sergio Nogales-Delgado

C 2025, 11(1), 19; https://doi.org/10.3390/c11010019 - 3 Mar 2025

Abstract

Nuclear energy has a great impact on the global energy mix. In Spain, it supplies over 20% of current energy requirements, demonstrating the relevance of nuclear power plants. These plants generate different types of waste (apart from radioactive) that should be managed. For [...] Read more.

Nuclear energy has a great impact on the global energy mix. In Spain, it supplies over 20% of current energy requirements, demonstrating the relevance of nuclear power plants. These plants generate different types of waste (apart from radioactive) that should be managed. For instance, the activated carbon included in filters (which neutralize isotopes in a possible radioactive leakage) should be periodically replaced. Nevertheless, these activated carbons might present long service lives, as they have not undergone any adsorption processes. Consequently, a considerable amount of activated carbon can be reused in alternative processes, even in the same nuclear power plant. The aim of this work was to assess the use of activated carbons (previously included in filters to prevent possible radioactive releases in primary circuits) for water treatment derived from the steam cycle of a nuclear power plant. A regeneration process (boron removal) was carried out (with differences between untreated carbon and after treatments, from S_BET = 684 m² g⁻¹ up to 934 m² g⁻¹), measuring the adsorption efficiency for ethanolamine and triton X-100. There were no significative results that support the adsorption effectiveness of the activated carbon tested for ethanolamine adsorption, whereas a high adsorption capacity was found for triton X-100 (q_L1 = 281 mg·g⁻¹), proving that factors such as porosity play an important role in the specific usage of activated carbons. Full article

(This article belongs to the Special Issue Carbon-Based Materials Applied in Water and Wastewater Treatment)

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17 pages, 4652 KiB

Open AccessArticle

A New Monohydrogen Phosphate-Selective Carbon Composite Membrane Electrode for Soil Water Samples

by Ozlem Tavukcuoglu, Vildan Erci, Fatih Ciftci, Ibrahim Isildak and Muhammed Zahid Kasapoglu

C 2025, 11(1), 18; https://doi.org/10.3390/c11010018 - 1 Mar 2025

Abstract

This study focused on developing a novel composite phosphate-selective electrode for on-site and real-time applications using a silver polyglutaraldehyde phosphate and carbon nanotube (CNT) matrix. CNT-silver polyglutaraldehyde phosphate compound was synthesized and characterized using Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), X-ray [...] Read more.

This study focused on developing a novel composite phosphate-selective electrode for on-site and real-time applications using a silver polyglutaraldehyde phosphate and carbon nanotube (CNT) matrix. CNT-silver polyglutaraldehyde phosphate compound was synthesized and characterized using Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). The potentiometric performance of the composite phosphate-selective electrode was then investigated. The results demonstrated that the composite phosphate-selective electrode exhibited good sensitivity, with a linear response in the concentration range of 1.0 × 10⁻⁴ to 1.0 × 10⁻² M for phosphate ions. The electrode also showed high selectivity towards phosphate ions compared to other anions, such as chloride and nitrate. Additionally, the electrode displayed a quick response time of less than 15 s, making it suitable for real-time measurements. The electrode was applied to surface and soil water samples. The results obtained from the water samples showed a strong correlation with those obtained from the preferred spectrophotometry method, highlighting the potential of the developed electrode for on-site and continuous monitoring of phosphate and offering an efficient and practical solution for various fields that require phosphate detection. Full article

(This article belongs to the Special Issue Carbon-Based Materials Applied in Water and Wastewater Treatment)

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15 pages, 10623 KiB

Open AccessArticle

Optical Transitions Dominated by Orbital Interactions in Two-Dimensional Fullerene Networks

by Haonan Bai, Xinwen Gai, Yi Zou and Jingang Wang

C 2025, 11(1), 17; https://doi.org/10.3390/c11010017 - 25 Feb 2025

Abstract

Fullerenes are a class of highly symmetric spherical carbon materials that have attracted significant attention in optoelectronic applications due to their excellent electron transport properties. However, the isotropy of their spherical structure often leads to disordered inter-sphere stacking in practical applications, limiting in-depth [...] Read more.

Fullerenes are a class of highly symmetric spherical carbon materials that have attracted significant attention in optoelectronic applications due to their excellent electron transport properties. However, the isotropy of their spherical structure often leads to disordered inter-sphere stacking in practical applications, limiting in-depth studies of their electron transport behavior. The successful fabrication of long-range ordered two-dimensional fullerene arrays has opened up new opportunities for exploring the structure–activity relationship in spatial charge transport. In this study, theoretical calculations were performed to analyze the effects of different periodic arrangements in two-dimensional fullerene arrays on electronic excitation and optical behavior. The results show that HLOPC₆₀ exhibits a strong absorption peak at 1050 nm, while TLOPC₆₀ displays prominent absorption features at 700 nm and 1300 nm, indicating that their electronic excitation characteristics are significantly influenced by the periodic structure. Additionally, analyses of orbital distribution and the spatial electron density reveal a close relationship between carrier transport and the structural topology. Quantitative studies further indicate that the interlayer interaction energies of the HLOPC₆₀ and TLOPC₆₀ arrangements are −105.65 kJ/mol and −135.25 kJ/mol, respectively. TLOPC₆₀ also exhibits stronger dispersion interactions, leading to enhanced interlayer binding. These findings provide new insights into the structural regulation of fullerene materials and offer theoretical guidance for the design and synthesis of novel organic optoelectronic materials. Full article

(This article belongs to the Special Issue High-Performance Carbon Materials and Their Composites)

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17 pages, 51050 KiB

Open AccessArticle

Towards Environmentally Friendly Buildings: An Assessment of the Mechanical Properties of Soil Mixtures with Graphene

by Federico Iorio Esposito, Paola Gallo Stampino, Letizia Ceccarelli, Marco Caruso, Giovanni Dotelli and Sergio Sabbadini

C 2025, 11(1), 16; https://doi.org/10.3390/c11010016 - 19 Feb 2025

Abstract

This study investigates the potential of graphene-based additives to improve the mechanical properties of compacted soil mixtures in rammed-earth construction, contributing to the development of environmentally friendly building materials. Two distinct soils were selected, combined with sand at optimized ratios, and treated with [...] Read more.

This study investigates the potential of graphene-based additives to improve the mechanical properties of compacted soil mixtures in rammed-earth construction, contributing to the development of environmentally friendly building materials. Two distinct soils were selected, combined with sand at optimized ratios, and treated with varying concentrations of a graphene liquid solution and a graphene-based paste (0.001, 0.005, 0.01, 0.05, and 0.1 wt.% relative to the soil-sand proportion). The effects of these additives were analyzed using the modified Proctor compaction and unconfined compressive strength (UCS) tests, focusing on parameters such as optimum water content (OWC), maximum dry density (MDD), maximum strength (q_u), and stiffness modulus (E). The results demonstrated that graphene’s influence on compaction behavior and mechanical performance depends strongly on the soil composition, with minimal variation between additive types. In finer soil mixtures, graphene disrupted particle packing, increased water demand, and reduced strength. In silt–sandy mixtures, graphene’s hydrophobicity and limited interaction with fines decreased water absorption and preserved density but likewise led to diminished strength. Conclusions from the experiments suggest a possible interaction between graphene, soil’s finer fraction, and potentially the swelling and non-swelling clay minerals, providing insights into the complex interplay between soil properties. Full article

(This article belongs to the Topic Application of Graphene-Based Materials, 2nd Edition)

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26 pages, 6250 KiB

Open AccessArticle

Activated Carbon Ammonization: Effects of the Chemical Composition of the Starting Material and the Treatment Temperature

by Silvia da C. Oliveira, Romulo C. Dutra, José J. L. León, Gesley A. V. Martins, Alysson M. A. Silva, Diana C. S. de Azevedo, Rafaelle G. Santiago, Daniel Ballesteros-Plata, Enrique Rodríguez-Castellón and Marcos J. Prauchner

C 2025, 11(1), 15; https://doi.org/10.3390/c11010015 - 19 Feb 2025

Abstract

N-containing carbon-based materials have been employed with claimed improved performance as an adsorbent of acidic molecules, volatile organic compounds (VOC), and metallic ions; catalyst; electrocatalyst; and supercapacitor. In this context, the present work provides valuable insights into the preparation of N-doped activated carbons [...] Read more.

N-containing carbon-based materials have been employed with claimed improved performance as an adsorbent of acidic molecules, volatile organic compounds (VOC), and metallic ions; catalyst; electrocatalyst; and supercapacitor. In this context, the present work provides valuable insights into the preparation of N-doped activated carbons (ACs) by thermal treatment in NH₃ atmosphere (ammonization). A commercial AC was submitted to two kinds of pretreatment: (i) reflux with dilute HNO₃; (ii) thermal treatment up to 800 °C in inert atmosphere. The original and modified ACs were subjected to ammonization up to different temperatures. ACs with N content up to ~8% were achieved. Nevertheless, the amount and type of inserted nitrogen depended on ammonization temperature and surface composition of the starting material. Remarkably, oxygenated acidic groups on the surface of the starting material favored nitrogen insertion at low temperatures, with formation of mostly aliphatic (amines, imides, and lactams), pyridinic, and pyrrolic nitrogens. In turn, high temperatures provoked the decomposition of labile aliphatic functions. Therefore, the AC prepared from the sample pre-treated with HNO₃, which had the highest content of oxygenated acidic groups among the materials submitted to ammonization, presented the highest N content after ammonization up to 400 °C but the lowest content after ammonization up to 800 °C. Full article

(This article belongs to the Special Issue Carbon Functionalization: From Synthesis to Applications)

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13 pages, 7070 KiB

Open AccessArticle

Porous Polysulfone/Activated Carbon Capsules as Scaffolds for Enzyme Immobilization

by Magdalena Olkiewicz, Josep M. Montornes, Ricard Garcia-Valls, Iwona Gulaczyk and Bartosz Tylkowski

C 2025, 11(1), 14; https://doi.org/10.3390/c11010014 - 17 Feb 2025

Abstract

Enzymes play a vital role in various industrial sectors and are essential components of many products. Hybrid enzyme-polymeric capsules were developed using polysulfone-activated carbon capsules as scaffolds. The polysulfone-activated carbon capsules with an average diameter of 2.55 mm were fabricated by applying a [...] Read more.

Enzymes play a vital role in various industrial sectors and are essential components of many products. Hybrid enzyme-polymeric capsules were developed using polysulfone-activated carbon capsules as scaffolds. The polysulfone-activated carbon capsules with an average diameter of 2.55 mm were fabricated by applying a phase inversion precipitation method. An increase in the amount of immobilized enzymes was observed with growth of activated carbon amount in polysulfone matrix. Enzyme immobilization was confirmed by the Bradford method, while Viscozyme^® L activity in carboxymethyl cellulose hydrolysis to glucose was measured by the Reducing Sugar DNS method. The recycling of the hybrid Viscozyme^® L-polysulfone/activated carbon capsules, and their reuse for subsequent cellulose hydrolysis was investigated and demonstrated repeatability of results. Full article

(This article belongs to the Special Issue Carbon-Based Polymer Composites: Synthesis, Processing, Characterization and Applications)

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9 pages, 3924 KiB

Open AccessEditor’s ChoiceArticle

Nanoparticle Air Filtration Using MXene-Coated Textiles

by Prastuti Upadhyay, Stefano Ippolito, Bita Soltan Mohammadlou, Michael S. Waring and Yury Gogotsi

C 2025, 11(1), 13; https://doi.org/10.3390/c11010013 - 12 Feb 2025

Abstract

Nanoparticles with aerodynamic diameters of less than 100 nm pose serious problems to human health due to their small size and large surface area. Despite continuous progress in materials science to develop air remediation technologies, efficient nanoparticle filtration has appeared to be challenging. [...] Read more.

Nanoparticles with aerodynamic diameters of less than 100 nm pose serious problems to human health due to their small size and large surface area. Despite continuous progress in materials science to develop air remediation technologies, efficient nanoparticle filtration has appeared to be challenging. This study showcases the great promise of MXene-coated polyester textiles to efficiently filter nanoparticles, achieving a high efficiency of ~90% within the 15–30 nm range. Using alkaline earth metal ions to assist textile coating drastically improves the filter performance by ca. 25%, with the structure–property relationship thoroughly assessed by electron microscopy and X-ray computed tomography. Such techniques confirm metal ions’ crucial role in obtaining fully coated and impregnated textiles, which increases tortuosity and structural features that boost the ultimate filtration efficiency. Our work provides a novel perspective on using MXene textiles for nanoparticle filtration, presenting a viable alternative to produce high-performance air filters for real-world applications. Full article

(This article belongs to the Section Carbon Materials and Carbon Allotropes)

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13 pages, 2081 KiB

Open AccessEditor’s ChoiceCommunication

Diffusion-Improved Recrystallization of Ammonia Doping to Enhancing the Optoelectronic and Thermoelectric Effects of Multi-Junction Carbon Nanotube Paper Diodes

by Jih-Hsin Liu and Cheng-Jhe Yen

C 2025, 11(1), 12; https://doi.org/10.3390/c11010012 - 12 Feb 2025

Abstract

This study focuses on fabricating flexible multi-junction diodes using carbon nanotubes (CNTs) as the base material, employing doping engineering and recrystallization-driven thermal diffusion techniques to enhance optoelectronic and thermoelectric properties. N-type CNTs are synthesized through ammonia doping and combined with intrinsic P-type CNTs [...] Read more.

This study focuses on fabricating flexible multi-junction diodes using carbon nanotubes (CNTs) as the base material, employing doping engineering and recrystallization-driven thermal diffusion techniques to enhance optoelectronic and thermoelectric properties. N-type CNTs are synthesized through ammonia doping and combined with intrinsic P-type CNTs to create PN multi-junction “buckypaper”. Post-diffusion processes improve junction crystallinity and doping gradients, significantly boosting the rectification ratio and optoelectronic and thermoelectric response. The device follows the superposition principle, achieving notable increases in thermoelectric and photovoltaic outputs, with the Seebeck coefficient rising from 5.7 μV/K to 24.4 μV/K. This study underscores the potential of flexible carbon-based devices for energy harvesting applications and advancing optoelectronic and thermoelectric systems. Full article

(This article belongs to the Special Issue Carbon Functionalization: From Synthesis to Applications)

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17 pages, 4446 KiB

Open AccessArticle

TiO₂/SWCNts: Linear and Nonlinear Optical Studies for Environmental Applications

by Saloua Helali

C 2025, 11(1), 11; https://doi.org/10.3390/c11010011 - 26 Jan 2025

Abstract

A series of single-walled carbon nanotube/titanium dioxide (SWCNTs/TiO₂) composites were prepared by the incorporation of various concentrations (0, 5, 10, 20 V.%) of SWCNTs in TiO₂. The prepared solutions were successfully formed on silicon and quartz substrates using the [...] Read more.

A series of single-walled carbon nanotube/titanium dioxide (SWCNTs/TiO₂) composites were prepared by the incorporation of various concentrations (0, 5, 10, 20 V.%) of SWCNTs in TiO₂. The prepared solutions were successfully formed on silicon and quartz substrates using the sol–gel spin-coating approach at 600 °C in ambient air. The X-ray diffraction method was used to investigate the structure of the samples. The absorbance and transmittance data of the samples were measured using a UV–vis spectrophotometer. Through the analysis of these data, both the linear and nonlinear optical properties of the samples were examined. Wemple–DiDomenico’s single-oscillator model was used to calculate the single-oscillator energy and dispersion energy. Finally, all samples’ photocatalytic performance was studied by the photodegradation of methylene blue (MB) in an aqueous solution under UV irradiation. It is found that the photocatalytic efficiency increases when increasing the SWCNT content. This research offers a new perspective for the creation of new photocatalysts for environmental applications. Full article

(This article belongs to the Special Issue Carbon Functionalization: From Synthesis to Applications)

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14 pages, 7961 KiB

Open AccessEditor’s ChoiceArticle

Markedly Enhanced Photoluminescence of Carbon Dots Dispersed in Deuterium Oxide

by Corneliu S. Stan, Adina Coroaba, Conchi O. Ania, Cristina Albu and Marcel Popa

C 2025, 11(1), 10; https://doi.org/10.3390/c11010010 - 22 Jan 2025

Abstract

In this work, we report some surprisingly interesting results in our pursuit to improve the photoluminescent emission of Carbon Dots (CDs) prepared from various precursors. By simply replacing the regular water with deuterium oxide (D₂O) as a dispersion medium, the emission [...] Read more.

In this work, we report some surprisingly interesting results in our pursuit to improve the photoluminescent emission of Carbon Dots (CDs) prepared from various precursors. By simply replacing the regular water with deuterium oxide (D₂O) as a dispersion medium, the emission intensity and the subsequent quantum efficiency of the radiative processes could be markedly enhanced. The present study was performed on our previous reported works related to CDs; in each case, the preparation path was maintained accordingly. For each type of CD, the emission intensity and the absolute photoluminescence quantum yield (PLQY) were highly improved, with, in certain cases, more-than-doubled values being recorded and the gain in performance being easily noticeable with the naked eye even in plain daylight. For each type of CD dispersed in regular water and heavy water, respectively, the photoluminescent properties were thoroughly investigated through Steady State, lifetime, and absolute PLQY. To further elucidate the mechanism involved in the photoluminescence intensity enhancement, samples of D₂O and H₂O dispersed CDs were embedded in a crosslinked Poly(acrylic acid) polymer matrix. The investigations revealed the major influence of the deuterium oxide dispersion medium over the PL emission properties of the investigated CDs. Full article

(This article belongs to the Section Carbon Materials and Carbon Allotropes)

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16 pages, 2648 KiB

Open AccessArticle

Raman Spectroscopy of Graphene/CNT Layers Deposited on Interdigit Sensors for Application in Gas Detection

by Stefan-Marian Iordache, Ana-Maria Iordache, Ana-Maria Florea (Raduta), Stefan Caramizoiu, Catalin Parvulescu, Flaviu Baiasu, Irina Negut and Bogdan Bita

C 2025, 11(1), 9; https://doi.org/10.3390/c11010009 - 20 Jan 2025

Abstract

Graphene/CNT layers were deposited onto platinum electrodes of an interdigitated sensor using radio-frequency magnetron sputtering. The graphene/CNTs were synthesized in an Argon atmosphere at a pressure of (2 × 10⁻²–5 × 10⁻³) mbar, with the substrate maintained at 300 [...] Read more.

Graphene/CNT layers were deposited onto platinum electrodes of an interdigitated sensor using radio-frequency magnetron sputtering. The graphene/CNTs were synthesized in an Argon atmosphere at a pressure of (2 × 10⁻²–5 × 10⁻³) mbar, with the substrate maintained at 300 °C either through continuous heating with an electronically controlled heater or by applying a −200 V bias using a direct current power supply throughout the deposition process. The study compares the surface morphology, carbon atom arrangement within the layer volumes, and electrical properties of the films as influenced by the different methods of substrate heating. X-ray diffraction and Raman spectroscopy confirmed the formation of CNTs within the graphene matrix. Additionally, scanning electron microscopy revealed that the carbon nanotubes are aligned and organized into cluster-like structure. The graphene/CNT layers produced at higher pressures present exponential I–V characteristics that ascertain the semiconducting character of the layers and their suitability for applications in gas sensing. Full article

(This article belongs to the Special Issue New Advances in Graphene Synthesis and Applications)

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Journal Description

C — Journal of Carbon Research

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