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13 pages, 2475 KiB

Open AccessArticle

Study of Marine Sponges Graphitization during Heat Treatment up to 1200 °C

by Olga V. Petrova, Danil V. Sivkov, Sergey V. Nekipelov, Alexander S. Vinogradov, Petr M. Korusenko, Sergey I. Isaenko, Roman N. Skandakov, Ksenia A. Bakina and Viktor N. Sivkov

Appl. Sci. 2023, 13(1), 128; https://doi.org/10.3390/app13010128 - 22 Dec 2022

Cited by 2 | Viewed by 1781

Abstract

The results of studies of marine sponge carbonization processes during thermal treatment in an argon atmosphere in the temperature range from room temperature to 1200 °C are presented. The spatial structure, atomic composition of native and carbonized sponges, and their changes during pyrolysis [...] Read more.

The results of studies of marine sponge carbonization processes during thermal treatment in an argon atmosphere in the temperature range from room temperature to 1200 °C are presented. The spatial structure, atomic composition of native and carbonized sponges, and their changes during pyrolysis were characterized using a set of methods that are informative at the macro- (thermogravimetric analysis, derivative thermogravimetric analysis, differential scanning calorimetry), micro- (Raman spectroscopy, scanning electron microscopy, energy dispersive spectroscopy), and nanoscales (X-ray absorption and photoelectron spectroscopy using synchrotron radiation and a sample charge compensation system). Preservation of the 3D architecture at the macro- and microlevels and graphitization of the interfibril medium with the formation of turbostratic graphite at the nanolevel were demonstrated. It was shown that the atomic contents of nitrogen, carbon, and oxygen in the spongin were ~2–3 at.%, ~5 at.%, and ~4 at.%, respectively. The matter concentrated in the space between the spongin fibrils included ~70 at.% carbon and ~11 at.% oxygen, with a large proportion of carbon (~63 at.%) involved in the formation of aromatic and C–C bonds and the remainder in carbon monoxide compounds. After the decomposition of spongin at 400 °C, this substance transformed into turbostratic graphite, preserving the 3D architecture of the original marine sponge as the temperature rose. Full article

(This article belongs to the Special Issue Practical Application of Functionalized Carbon-Based Nanomaterials)

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17 pages, 4228 KiB

Open AccessArticle

Composite Based on Multi-Walled Carbon Nanotubes and Manganese Oxide with Rhenium Additive for Supercapacitors: Structural and Electrochemical Studies

by Petr M. Korusenko and Sergey N. Nesov

Appl. Sci. 2022, 12(24), 12827; https://doi.org/10.3390/app122412827 - 14 Dec 2022

Cited by 5 | Viewed by 2713

Abstract

The structure and electrochemical characteristics of composites based on multi-walled carbon nanotubes (MWCNTs) and manganese oxide with the addition of rhenium oxide has been studied. It has shown that the decorating of the MWCNT surface with layers or nanoparticles of manganese oxide (Mn(III) [...] Read more.

The structure and electrochemical characteristics of composites based on multi-walled carbon nanotubes (MWCNTs) and manganese oxide with the addition of rhenium oxide has been studied. It has shown that the decorating of the MWCNT surface with layers or nanoparticles of manganese oxide (Mn(III) + Mn(IV)) provides more than a twofold increase in the value of the specific capacitance at low potential scan rates. However, composites based only on manganese oxide exhibit poor electrochemical behavior and the value of the specific capacitance decreases rapidly with increasing potential scan rate due to the limitation of diffusion processes. The addition of rhenium oxide to composites significantly increases their electrochemical properties due to changes in the chemical composition and morphology of composites. Studies of the structure and chemical state have shown that an improvement in the specific capacitance is provided by increasing in the proportion of Mn(IV) oxide in such composites, which has the ability to rapidly and completely reverse redox reactions and has lower electrical resistance values, compared to Mn(III) oxide. A detailed analysis of the voltammetric data showed that an increase in the rate capability in composites with the addition of rhenium oxide can also be provided by increasing the availability of the electrode surface for electrolyte ions and increasing the amount of charge stored due to the formation of a double electric layer. Full article

(This article belongs to the Special Issue Practical Application of Functionalized Carbon-Based Nanomaterials)

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10 pages, 1583 KiB

Open AccessArticle

Quantitative Characterization of Oxygen-Containing Groups on the Surface of Carbon Materials: XPS and NEXAFS Study

by Danil V. Sivkov, Olga V. Petrova, Sergey V. Nekipelov, Alexander S. Vinogradov, Roman N. Skandakov, Ksenia A. Bakina, Sergey I. Isaenko, Anatoly M. Ob’edkov, Boris S. Kaverin, Ilya V. Vilkov and Viktor N. Sivkov

Appl. Sci. 2022, 12(15), 7744; https://doi.org/10.3390/app12157744 - 1 Aug 2022

Cited by 26 | Viewed by 4793

Abstract

The results of the comparative quantitative study of oxygen-containing groups adsorbed on the surface of carbonized sponge scaffold (CSS), highly oriented pyrolytic graphite (HOPG), fullerite C₆₀ and multi-walled carbon nanotubes (MWCNTs) introduced into a high vacuum from the atmosphere without any pre-treatment [...] Read more.

The results of the comparative quantitative study of oxygen-containing groups adsorbed on the surface of carbonized sponge scaffold (CSS), highly oriented pyrolytic graphite (HOPG), fullerite C₆₀ and multi-walled carbon nanotubes (MWCNTs) introduced into a high vacuum from the atmosphere without any pre-treatment of the surface are discussed. The studied materials are first tested by XRD and Raman spectroscopy, and then quantitatively characterized by XPS and NEXAFS. The research results showed the presence of carbon oxides and water-dissociation products on the surfaces of materials. It was shown that main source of oxygen content (~2%) on the surface of HOPG, MWCNTs, and C₆₀ powder is water condensed from the atmosphere in the form of an adsorbed water molecule and hydroxyl group. On the CSS surface, oxygen atoms are present in the forms of carbon oxides (4–5%) and adsorbed water molecules and hydroxyl groups (5–6%). The high content of adsorbed water on the CSS surface is due to the strong roughness and high porosity of the surface. Full article

(This article belongs to the Special Issue Practical Application of Functionalized Carbon-Based Nanomaterials)

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12 pages, 3116 KiB

Open AccessArticle

Effect of Nitrogen Atoms in the CNT Structure on the Gas Sensing Properties of PANI/CNT Composite

by Ivan A. Lobov, Nadim A. Davletkildeev, Sergey N. Nesov, Denis V. Sokolov and Petr M. Korusenko

Appl. Sci. 2022, 12(14), 7169; https://doi.org/10.3390/app12147169 - 16 Jul 2022

Cited by 5 | Viewed by 1755

Abstract

Herein we report the gas-sensitive properties to ammonia (at 2–10 ppm) of individual nanostructures of a polyaniline/nitrogen-doped carbon nanotube composite with a nitrogen content of 0 at.% (uCNTs), 2 at.% (N-CNTs) and 4 at.% (N⁺-CNTs). Doping of nanotubes with nitrogen was [...] Read more.

Herein we report the gas-sensitive properties to ammonia (at 2–10 ppm) of individual nanostructures of a polyaniline/nitrogen-doped carbon nanotube composite with a nitrogen content of 0 at.% (uCNTs), 2 at.% (N-CNTs) and 4 at.% (N⁺-CNTs). Doping of nanotubes with nitrogen was carried out in order to both reduce the electron work function, to form a potential barrier at the “PANI-CNTs” interface, and reduce the contribution of nanotubes to the composite conductivity. An increase in the nitrogen content in CNTs leads to an increase in conductivity, a decrease in the work function, and the formation of defects in the outer walls of CNTs. It was found that the structural and chemical state of the polymer layer of all composites is the same. However, polymer morphology on nanotubes changes dramatically with increasing nitrogen content in CNTs: a thin smooth layer on uCNTs, a globular layer on N-CNTs, and a thick layer with a sheet-like structure on N⁺-CNTs. All composites showed the same response time (~20 s) and recovery time (~120 s). Ammonia sensitivity was 10.5 ± 0.2, 15.3 ± 0.5 and 2.2 ± 0.1 ppm⁻¹ for PANI/uCNTs, PANI/N-CNTs and PANI/N⁺-CNTs, respectively. Based on the results obtained here, we came to the conclusion that the morphological features of the polymer layer on CNTs with different nitrogen content have a dominant effect on the gas reaction than the change in the electronic properties of the polymer at the interface “PANI-CNT”. Full article

(This article belongs to the Special Issue Practical Application of Functionalized Carbon-Based Nanomaterials)

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9 pages, 1220 KiB

Open AccessArticle

Influence of Twist-Angle and Concentration Disorder on the Density of Electronic States of Twisted Graphene

by Nadezhda Bobenko, Yurii Chumakov and Anna Belosludtseva

Appl. Sci. 2022, 12(9), 4109; https://doi.org/10.3390/app12094109 - 19 Apr 2022

Viewed by 1660

Abstract

In this paper, we present an approach that makes it possible to describe, from unified physical considerations, the influence of rotation-angle and concentration disorder on the density of electronic states of two-layer twisted graphene. The electron relaxation time and the density of electronic [...] Read more.

In this paper, we present an approach that makes it possible to describe, from unified physical considerations, the influence of rotation-angle and concentration disorder on the density of electronic states of two-layer twisted graphene. The electron relaxation time and the density of electronic states near the Fermi level are calculated by considering the multiple elastic scattering of electrons by impurities and structural inhomogeneities of the short-range order type. An analysis is presented of the change in the contributions to the density of electronic states from electron scattering on foreign atoms with variations in the defectiveness of the structure, impurity concentration, temperature, and the external electric field magnitude. It is shown that the formation of short-range order areas by foreign atoms in the first coordination sphere relative to the surface of the material can lead to the opening of a gap in the density of electronic states of twisted graphene. Point defects and short-range order regions formed by foreign atoms in the second coordination sphere lead to metallization of twisted graphene. Full article

(This article belongs to the Special Issue Practical Application of Functionalized Carbon-Based Nanomaterials)

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14 pages, 2631 KiB

Open AccessFeature PaperArticle

Electrically Conductive Nanocomposite Fibers for Flexible and Structural Electronics

by Bartłomiej Podsiadły, Piotr Walter, Michał Kamiński, Andrzej Skalski and Marcin Słoma

Appl. Sci. 2022, 12(3), 941; https://doi.org/10.3390/app12030941 - 18 Jan 2022

Cited by 3 | Viewed by 2263

Abstract

The following paper presents a simple, low-cost, and repeatable manufacturing process for fabricating conductive, elastic carbon-elastomer nanocomposite fibers for applications in the textile industry and beyond. The presented method allows for the manufacturing of fibers with a diameter of 0.2 mm, containing up [...] Read more.

The following paper presents a simple, low-cost, and repeatable manufacturing process for fabricating conductive, elastic carbon-elastomer nanocomposite fibers for applications in the textile industry and beyond. The presented method allows for the manufacturing of fibers with a diameter of 0.2 mm, containing up to 50 vol. % of graphite powder, 10 vol. % of CNT, and a mix of both fillers. As a result, resistivity below 0.2 Ωm for the 0.2 mm-diameter fibers was achieved. Additionally, conductive fibers are highly elastic, which makes them suitable for use in the textile industry as an element of circuits. The effect of strain on the change in resistance was also tested. Researches have shown that highly conductive fibers can withstand strain of up to 40%, with resistivity increasing nearly five times compared to the unstretched fiber. This research shows that the developed composites can also be used as strain sensors in textronic systems. Finally, functional demonstrators were made by directly sewing the developed fibers into a cotton fabric. First, the non-quantitative tests indicate the feasibility of using the composites as conductive fibers to power components in textronic systems and for bending detection. Full article

(This article belongs to the Special Issue Practical Application of Functionalized Carbon-Based Nanomaterials)

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16 pages, 3129 KiB

Open AccessArticle

The Formation of Nanoscale Closed Graphene Surfaces during Fullerite C₆₀ Hot Isostatic Pressing

by Danil V. Sivkov, Olga V. Petrova, Sergey V. Nekipelov, Alexander S. Vinogradov, Roman N. Skandakov, Ksenia A. Bakina, Sergey I. Isaenko, Anatoly M. Ob’edkov, Boris S. Kaverin and Viktor N. Sivkov

Appl. Sci. 2021, 11(24), 11646; https://doi.org/10.3390/app112411646 - 8 Dec 2021

Cited by 5 | Viewed by 2797

Abstract

The fullerite C₆₀ modified by hot isostatic pressing (HIP) at 0.1 GPa in argon near and beyond its thermal stability region (920–1270 K temperature interval) was studied by X-ray diffractometry, Raman spectroscopy, ultra soft X-ray photoelectron and near edge X-ray absorption fine [...] Read more.

The fullerite C₆₀ modified by hot isostatic pressing (HIP) at 0.1 GPa in argon near and beyond its thermal stability region (920–1270 K temperature interval) was studied by X-ray diffractometry, Raman spectroscopy, ultra soft X-ray photoelectron and near edge X-ray absorption fine structure spectroscopy. It was found that the C₆₀ molecules merge into closed nanocapsules with a graphene surface during the thermal treatment. The conducted studies showed that using HIP treatment of the fullerite C₆₀, it is possible to obtain a chemically resistant material with a high hardness and elasticity, as well as a density lower than that of the graphite. This new material, consisting of closed graphene nanocapsules 2–5 nm in size, formed by sp² covalent bonds between carbon atoms is promising for various applications, and as a basis for the synthesis of new composite materials. Full article

(This article belongs to the Special Issue Practical Application of Functionalized Carbon-Based Nanomaterials)

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10 pages, 2378 KiB

Open AccessArticle

Enhanced Performance of PVDF Composite Ultrafiltration Membrane via Degradation of Collagen-Modified Graphene Oxide

by Yonggang Hou, Shenghua Lv, Haoyan Hu, Xinming Wu and Leipeng Liu

Appl. Sci. 2021, 11(23), 11513; https://doi.org/10.3390/app112311513 - 4 Dec 2021

Cited by 8 | Viewed by 2392

Abstract

The collagen obtained from chrome leather waste can be used to modify graphene oxide (GO) to prepare polyvinylidene fluoride (PVDF) composite ultrafiltration membranes, a process that is conducive to the recovery of leather waste, comprehensive utilization of GO and improved performance of the [...] Read more.

The collagen obtained from chrome leather waste can be used to modify graphene oxide (GO) to prepare polyvinylidene fluoride (PVDF) composite ultrafiltration membranes, a process that is conducive to the recovery of leather waste, comprehensive utilization of GO and improved performance of the membrane. In this paper, collagen-modified GO (CGO) was prepared by degradation of collagen from chrome leather waste and used to prepare a PVDF composite ultrafiltration membrane. The results show that the carboxyl content of CGO and dispersion were improved. The water flux and flux recovery rate of the modified ultrafiltration membrane were improved. The bovine serum albumin (BSA) intercepted on the membrane surface was easy to clean and the antifouling performance improved. The performance of the membrane decreased when the GO content exceeded 0.75 wt%, while CGO can reach 1.0 wt% without agglomeration due to its good dispersion. Full article

(This article belongs to the Special Issue Practical Application of Functionalized Carbon-Based Nanomaterials)

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13 pages, 3315 KiB

Open AccessArticle

Reduced Graphene Oxide-Metalloporphyrin Sensors for Human Breath Screening

by Bo Mi Lee, Ameen Eetemadi and Ilias Tagkopoulos

Appl. Sci. 2021, 11(23), 11290; https://doi.org/10.3390/app112311290 - 29 Nov 2021

Cited by 14 | Viewed by 2624

Abstract

The objective of this study is to validate reduced graphene oxide (RGO)-based volatile organic compounds (VOC) sensors, assembled by simple and low-cost manufacturing, for the detection of disease-related VOCs in human breath using machine learning (ML) algorithms. RGO films were functionalized by four [...] Read more.

The objective of this study is to validate reduced graphene oxide (RGO)-based volatile organic compounds (VOC) sensors, assembled by simple and low-cost manufacturing, for the detection of disease-related VOCs in human breath using machine learning (ML) algorithms. RGO films were functionalized by four different metalloporphryins to assemble cross-sensitive chemiresistive sensors with different sensing properties. This work demonstrated how different ML algorithms affect the discrimination capabilities of RGO–based VOC sensors. In addition, an ML-based disease classifier was derived to discriminate healthy vs. unhealthy individuals based on breath sample data. The results show that our ML models could predict the presence of disease-related VOC compounds of interest with a minimum accuracy and F1-score of 91.7% and 83.3%, respectively, and discriminate chronic kidney disease breath with a high accuracy, 91.7%. Full article

(This article belongs to the Special Issue Practical Application of Functionalized Carbon-Based Nanomaterials)

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12 pages, 15819 KiB

Open AccessArticle

In Situ Generation of Hydrogen Peroxide Using Polymetallic-Doped g-C₃N₄ for Pollutant Removal

by Liyan Wang, Jianqing Ma, Qianhui Guo, Liang Liu, Jiangnan Shou, Aojie Sun and Liaoyuan Zhao

Appl. Sci. 2021, 11(22), 10797; https://doi.org/10.3390/app112210797 - 15 Nov 2021

Cited by 2 | Viewed by 2352

Abstract

Fenton reaction is a powerful technology for pollutants’ removal from water. However, the cost of H₂O₂ becomes one of the major stumbling blocks in its application. H₂O₂ has a relatively high price and is easily decomposed during [...] Read more.

Fenton reaction is a powerful technology for pollutants’ removal from water. However, the cost of H₂O₂ becomes one of the major stumbling blocks in its application. H₂O₂ has a relatively high price and is easily decomposed during transportation and use; therefore, in situ synthesis of H₂O₂ could improve economic benefits effectively. In this study, a Fe/Ni/Pd ternary metal-doped graphitic carbon nitride (FeNi-Pd@CN) is prepared, and in situ H₂O₂ generation using formic acid as hydrogen sources for organics removal was proved. The catalyst is advantageous, as H₂O₂ could accumulate to 1.69 mmol/L in 150 min when pumping air rather than oxygen gases in other studies. Furthermore, 92.0% of Acid Red 73 (200 mg/L) and 93.2% of tetracycline hydrochloride (10 mg/L) could be removed in 150 min without any pH adjustment. Characterization results show that the catalyst has good stability in metal leaching and reuse tests. It is proved that •OH and •O₂⁻ are the main reactive oxygen species, and a synergistic effect between Fe and Ni exists that enhances ROS generation for organics degradation. This work offers a promising method to remove refectory organic contaminants from industrial wastewater. Full article

(This article belongs to the Special Issue Practical Application of Functionalized Carbon-Based Nanomaterials)

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10 pages, 5146 KiB

Open AccessArticle

Influence of Impurity Scattering on Surface Plasmons in Graphene in the Lindhard Approximation

by Mousa Bahrami and Panagiotis Vasilopoulos

Appl. Sci. 2021, 11(21), 10147; https://doi.org/10.3390/app112110147 - 29 Oct 2021

Cited by 1 | Viewed by 1663

Abstract

We study the influence of impurity scattering on transverse magnetic (TM) and transverse electric (TE) surface plasmons (SPs) in graphene using the Lindhard approximation. We show how the behaviour and domains of TM SPs are affected by the impurity strength

γ

and determine [...] Read more.

We study the influence of impurity scattering on transverse magnetic (TM) and transverse electric (TE) surface plasmons (SPs) in graphene using the Lindhard approximation. We show how the behaviour and domains of TM SPs are affected by the impurity strength

γ

and determine the critical value

γ_{c}

below which no SPs exist. The quality factor of TM SPs, for single-band and two-band transitions, is proportional to the square of

α λ_{S P} / γ

, with

α

being the fine-structure constant and

λ_{S P}

being the plasmon wavelength. In addition, we show that impurity scattering suppresses TE SPs. Full article

(This article belongs to the Special Issue Practical Application of Functionalized Carbon-Based Nanomaterials)

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14 pages, 47715 KiB

Open AccessArticle

Effect of Graphene Nanoplatelet on the Carbonation Depth of Concrete under Changing Climate Conditions

by Yingzi Zhang, Yanze Wang, Mingqian Yang, Huatao Wang, Guofang Chen and Song Zheng

Appl. Sci. 2021, 11(19), 9265; https://doi.org/10.3390/app11199265 - 6 Oct 2021

Cited by 8 | Viewed by 2471

Abstract

Climate change has been unprecedented in the past decades or even thousands of years, which has had an adverse impact on the mechanical properties of concrete structures. Many researchers have begun to study new concrete materials. Graphene nanoplatelet (GNP) is an attractive nanomaterial [...] Read more.

Climate change has been unprecedented in the past decades or even thousands of years, which has had an adverse impact on the mechanical properties of concrete structures. Many researchers have begun to study new concrete materials. Graphene nanoplatelet (GNP) is an attractive nanomaterial that can change the crystal structure of concrete and improve durability. The aim of the present study was to investigate the effect of GNP (0.05%wt) on the carbonation depth of concrete under simulated changing climate conditions (varying temperature, relative humidity, and carbon dioxide (CO₂) concentration), and compare it with ordinary concrete. When the concentration of CO₂ is variable, the carbonation depth of graphene concrete is 10% to 20% lower than that of ordinary concrete. When the temperature is lower than 33 °C, the carbonation depth of graphene concrete is less than that of the control sample; however, above 33 °C, the thermal conductivity of GNP increases the carbonation reaction rate of concrete. When the humidity is a variable, the carbonation depth of graphene concrete is less than 15% to 30% of ordinary concrete, and when the humidity is higher than 78%, the difference in the carbonation depth between the ordinary concrete and the graphene concrete decreases gradually. The overall results indicated that GNP has a favorable effect on anti-carbonation performance under changing climate conditions. Full article

(This article belongs to the Special Issue Practical Application of Functionalized Carbon-Based Nanomaterials)

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14 pages, 2688 KiB

Open AccessFeature PaperArticle

Vitamin C-Assisted Fabrication of Aerogels from Industrial Graphene Oxide for Gaseous Hexamethyldisiloxane Adsorption

by Yanhui Zheng, Xifeng Hou, Xiaolong Ma, Zelin Hao and Zichuan Ma

Appl. Sci. 2021, 11(18), 8486; https://doi.org/10.3390/app11188486 - 13 Sep 2021

Cited by 6 | Viewed by 2258

Abstract

Volatile methyl siloxanes (VMSs) as a trace impurity in biogas decreases its energy utilization, and thus need to be removed. In this paper, a one-step hydrothermal reduction was performed to produce three-dimensional reduced graphene oxide aerogels (rGOAs) using industrial-grade graphene oxide (IGGO) as [...] Read more.

Volatile methyl siloxanes (VMSs) as a trace impurity in biogas decreases its energy utilization, and thus need to be removed. In this paper, a one-step hydrothermal reduction was performed to produce three-dimensional reduced graphene oxide aerogels (rGOAs) using industrial-grade graphene oxide (IGGO) as raw material and vitamin C (VC) as a reductant to facilitate the fabrication of rGOAs. The synthesis of rGOAs was a simple, green, and energy-efficient process. The developed rGOAs were characterized using the Brunauer–Emmett–Teller method, Raman spectrometry, scanning electron microscopy, Fourier-transform infrared spectroscopy, X-ray diffraction measurements and contact angle. The results obtained showed that rGOA-1 with a VC/IGGO ratio of 1/1 (m/m) exhibited a hierarchical porous structure and super-hydrophobicity, yielding a high specific surface area (137.9 m² g⁻¹) and superior water contact angle (143.8°). The breakthrough adsorption capacity of rGOA-1 for hexamethyldisiloxane (L2, a VMS model) was 11 times higher than that of IGGO. Low inlet concentration and bed temperature were considered beneficial for the L2 adsorption. Interestingly, rGOA-1 was less sensitive to water, and it was readily regenerated for reuse by annealing at 80 °C. The rGOAs have been demonstrated to have great potential for the removal of siloxanes from biogas. Full article

(This article belongs to the Special Issue Practical Application of Functionalized Carbon-Based Nanomaterials)

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18 pages, 3689 KiB

Open AccessArticle

MHD Flow and Heat Transfer of Hybrid Nanofluid over an Exponentially Shrinking Surface with Heat Source/Sink

by Mohamad Nizam Othman, Alias Jedi and Nor Ashikin Abu Bakar

Appl. Sci. 2021, 11(17), 8199; https://doi.org/10.3390/app11178199 - 3 Sep 2021

Cited by 29 | Viewed by 3236

Abstract

In nanotechnology research, nanofluid technology contributes many applications to engineering applications and industry, such as power generation, solar collection, heat exchangers for cooling, and many more. However, there are still a few constraints in terms of heat transfer enhancement, although nanofluid properties show [...] Read more.

In nanotechnology research, nanofluid technology contributes many applications to engineering applications and industry, such as power generation, solar collection, heat exchangers for cooling, and many more. However, there are still a few constraints in terms of heat transfer enhancement, although nanofluid properties show the best heat transfer rate compared with conventional fluids. Thus, this study was conducted for the purpose of investigating the behaviors of flow and heat transfer of hybrid nanofluid with carbon nanotubes (CNTs) on a permeable exponentially shrinking surface, as well as investigating the effects of a magnetic field and heat source/sink. This study was conducted by developing a mathematical model, which was the Tiwari–Das model for momentum and energy equations, and then transforming the model’s partial differential equations (PDEs) to ordinary differential equations (ODEs) using a similarity solution. Next, these equations were solved numerically using the MATLAB bvp4c boundary value problem solver. The authors particularly explored these behaviors with a few variations. Based on the results obtained, it was found that dual solutions exist in a specific range of the shrinking case,

λ_{c} < λ < - λ

and that the critical point

λ_{c}

also exists in a range of −1.5 <

λ_{c}

< −1 with different parameters. For the heat source/sink effect, the Nusselt number was higher when heat sink case ε < 0, whereas it decreased when the heat source case ε > 0. Therefore, this study deduced that the heat transfer rate of hybrid nanofluid (CNTs/Cu–water) is better than regular nanofluid (CNT–water) and conventional fluid (water). The present study took into consideration the problem of MHD flow and heat transfer analysis of a hybrid nanofluid towards an exponentially shrinking surface with the presence of heat source/sink and thermal radiation effects. The authors show that dual solutions exist within a specific range of values due to the shrinking case. The current work is predicted to have numerous benefits in equivalent real-world systems. Full article

(This article belongs to the Special Issue Practical Application of Functionalized Carbon-Based Nanomaterials)

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14 pages, 4964 KiB

Open AccessFeature PaperArticle

Carbon Allotropes/Epoxy Nanocomposites as Capacitive Energy Storage/Harvesting Systems

by Sotirios G. Stavropoulos, Aikaterini Sanida and Georgios C. Psarras

Appl. Sci. 2021, 11(15), 7059; https://doi.org/10.3390/app11157059 - 30 Jul 2021

Cited by 5 | Viewed by 2137

Abstract

The present work aims at the development and characterization of carbon/polymer matrix nanocomposites, which will be able to operate as compact materials systems for energy storage and harvesting. Series of polymer nanocomposites employing different types of carbon allotropes (carbon black nanoparticles, multi-walled carbon [...] Read more.

The present work aims at the development and characterization of carbon/polymer matrix nanocomposites, which will be able to operate as compact materials systems for energy storage and harvesting. Series of polymer nanocomposites employing different types of carbon allotropes (carbon black nanoparticles, multi-walled carbon nanotubes, graphene nanoplatelets and nanodiamonds) were developed varying the filler type and content. The energy storage ability of the systems was examined under AC and DC conditions to evaluate the influence of temperature, DC voltage and different types of filler content upon the stored and harvested energy. Experimental data confirmed the ability of the examined systems to store energy and release it on demand via a fast charge/discharge process. The addition of carbon nanoparticles significantly enhances the energy density of the systems. The coefficient of energy efficiency (n_eff) was determined for all systems, reaching up to 80% for the nanocomposite with 5 phr (parts per hundred resin per mass) carbon black content. In order to examine the optimal operational conditions of the systems, their structural integrity and thermomechanical properties were also investigated by means of static tensile tests, Dynamic Mechanical Analysis (DMA) and Differential Scanning Calorimetry (DSC). Full article

(This article belongs to the Special Issue Practical Application of Functionalized Carbon-Based Nanomaterials)

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8 pages, 2177 KiB

Open AccessArticle

Fabrication of Eco-Friendly Graphene Nanoplatelet Electrode for Electropolishing and Its Properties

by Junyoung Jeong, Wanjun Yoon, Bongjin Chung, Giyoung Jeon and Seongwoo Ryu

Appl. Sci. 2021, 11(7), 3224; https://doi.org/10.3390/app11073224 - 3 Apr 2021

Cited by 4 | Viewed by 2095

Abstract

Electropolishing is one of the most widely applied metal polishing techniques for passivating and deburring metal parts. Copper is often used as cathode electrode for electropolishing due to its low electrical resistance and low flow values. However, during the electropolishing process, elution of [...] Read more.

Electropolishing is one of the most widely applied metal polishing techniques for passivating and deburring metal parts. Copper is often used as cathode electrode for electropolishing due to its low electrical resistance and low flow values. However, during the electropolishing process, elution of the cathode electrode caused by the electrolyte and remaining oxygen gas also causes critical water pollution and inhibits electropolishing efficiency. Therefore, to achieve an efficient and eco-friendly electropolishing process, development of a highly corrosion resistive and conductive electrode is necessary. We developed a highly oriented graphene nanoplatelet (GNP) electrode that minimizes water pollution in the electropolishing process. We functionalized GNP by a one-step mass-productive ball-milling process and non-covalent melamine functionalization. Melamine is an effective amphiphilic molecule that enhances dispersibility and nematic liquid crystal phase transformation of GNP. The functionalization mechanism and the material interaction were confirmed by Raman spectroscopy after high-speed shear printing. After the electropolishing process by melamine-functionalized GNP electrodes, 304 stainless steel samples were noticeably polished as copper electrodes and elution of carbon was over 50 times less than was the case when using copper electrodes. This electropolishing performance of a highly oriented GNP electrode indicates that melamine-functionalized GNP has great potential for eco-friendly electropolishing applications. Full article

(This article belongs to the Special Issue Practical Application of Functionalized Carbon-Based Nanomaterials)

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9 pages, 3174 KiB

Open AccessArticle

X-ray Photoelectron Spectra of Ag-Au Colloidal Nanoparticles after Interaction with Linear Carbon Chains

by Ivan S. Zhidkov, Ernst Z. Kurmaev, Marcello Condorelli, Seif O. Cholakh, Alexey S. Boyarchenkov, Enza Fazio and Luisa D’Urso

Appl. Sci. 2021, 11(2), 685; https://doi.org/10.3390/app11020685 - 12 Jan 2021

Cited by 4 | Viewed by 3152

Abstract

The results of X-ray photoelectron spectra (XPS) characterization of the surface of Ag-Au colloidal nanoparticles (Ag-Au NPs), prepared by laser ablation in water before and after interaction with linear carbon chains (LCC), are presented. No additional features appear in high-energy resolved XPS core [...] Read more.

The results of X-ray photoelectron spectra (XPS) characterization of the surface of Ag-Au colloidal nanoparticles (Ag-Au NPs), prepared by laser ablation in water before and after interaction with linear carbon chains (LCC), are presented. No additional features appear in high-energy resolved XPS core level spectra of Ag-Au NPs which indicates that surface is not oxidized. The measurements of XPS Ag 3d-spectrum of (Ag-Au)@LCC manifests the additional low-energy structure that is associated with the formation of Ag–C bonds. The charge transfer between Au atoms on the NPs surface and LCC was established. Additionally, some oxidation of the Ag atoms on the surface of (Ag-Au)@LCC is observed which arises during laser ablation in water. We assume that oxidative species will preferably interact with the areas outside the LCC instead of oxidizing the carbon chains which was confirmed by XPS C 1s spectra. Full article

(This article belongs to the Special Issue Practical Application of Functionalized Carbon-Based Nanomaterials)

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Review

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23 pages, 3244 KiB

Open AccessReview

The Use of Carbon-Containing Compounds to Prepare Functional and Structural Composite Materials: A Review

by Elena G. Zemtsova, Andrey Yu. Arbenin, Yuri V. Sidorov, Nikita F. Morozov, Petr M. Korusenko, Boris N. Semenov and Vladimir M. Smirnov

Appl. Sci. 2022, 12(19), 9945; https://doi.org/10.3390/app12199945 - 3 Oct 2022

Cited by 12 | Viewed by 2865

Abstract

The review presents data on the synthesis, properties of carbon-containing compounds, and their application in the technology of obtaining functional and structural composites. Such materials are widely used in recent years due to their good physical and mechanical properties. The review discusses in [...] Read more.

The review presents data on the synthesis, properties of carbon-containing compounds, and their application in the technology of obtaining functional and structural composites. Such materials are widely used in recent years due to their good physical and mechanical properties. The review discusses in detail the influence of the chemical composition of various carbon-containing substances and the size of the dispersed phase on the mechanical and physical properties of produced metal matrix composite. The review also concerns methods for the modern synthesis of graphene, carbon nanotubes, and metallic functional and structural composites with reinforcing carbon-containing compounds. Additionally, the results of metal matrix composite modeling are presented. They show that the improved mechanical properties of CNT–Al composites can be attributed to three factors: CNT hardening, matrix grain refinement, and layered architecture. Full article

(This article belongs to the Special Issue Practical Application of Functionalized Carbon-Based Nanomaterials)

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19 pages, 3213 KiB

Open AccessReview

Functionalized Carbon-Based Electrochemical Sensors for Food and Alcoholic Beverage Safety

by Zhongjie Yang, Xiaofei Zhang and Jun Guo

Appl. Sci. 2022, 12(18), 9082; https://doi.org/10.3390/app12189082 - 9 Sep 2022

Cited by 16 | Viewed by 2673

Abstract

Food is a necessity in people’s lives. Equally importantly, alcoholic beverages are also highly demanded globally due to the indispensable role they play in cultural, social, and ritual events. However, the production of food and alcoholic beverages suffers from a variety of contaminants, [...] Read more.

Food is a necessity in people’s lives. Equally importantly, alcoholic beverages are also highly demanded globally due to the indispensable role they play in cultural, social, and ritual events. However, the production of food and alcoholic beverages suffers from a variety of contaminants, such as toxins, pesticides, antibiotic residues, and heavy metals, which are seriously harmful to human beings. These urgent threats have raised the awareness of the need to improve product quality and safety via developing effective, rapid, and economical monitoring and detecting methods. Fortunately, due to their numerous advantages, including high sensitivity, short response time, low cost, and easy portability, electrochemistry sensors have made huge contributions to ensuring the quality of food and alcoholic beverages. The purpose of this review is to introduce applications of electrochemical sensors to foods and alcoholic beverages, and to highlight the important role of carbon-based materials (i.e., carbon dots, carbon nanotubes, and graphene) as electrochemical sensors in detecting various contaminants. In addition, the preparation methods of these carbon-based electrochemical sensors and corresponding detection mechanisms are discussed in detail. It is hoped that this review can inspire more innovative detection technologies for ensuring the safety of food and alcoholic beverages. Full article

(This article belongs to the Special Issue Practical Application of Functionalized Carbon-Based Nanomaterials)

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29 pages, 8836 KiB

Open AccessReview

Electrospinning-Based Carbon Nanofibers for Energy and Sensor Applications

by Trong Danh Nguyen and Jun Seop Lee

Appl. Sci. 2022, 12(12), 6048; https://doi.org/10.3390/app12126048 - 14 Jun 2022

Cited by 25 | Viewed by 7154

Abstract

Carbon nanofibers (CNFs) are the most basic structure of one-dimensional nanometer-scale sp² carbon. The CNF’s structure provides fast current transfer and a large surface area and it is widely used as an energy storage material and as a sensor electrode material. Electrospinning [...] Read more.

Carbon nanofibers (CNFs) are the most basic structure of one-dimensional nanometer-scale sp² carbon. The CNF’s structure provides fast current transfer and a large surface area and it is widely used as an energy storage material and as a sensor electrode material. Electrospinning is a well-known technology that enables the production of a large number of uniform nanofibers and it is the easiest way to mass-produce CNFs of a specific diameter. In this review article, we introduce an electrospinning method capable of manufacturing CNFs using a polymer precursor, thereafter, we present the technologies for manufacturing CNFs that have a porous and hollow structure by modifying existing electrospinning technology. This paper also discusses research on the applications of CNFs with various structures that have recently been developed for sensor electrode materials and energy storage materials. Full article

(This article belongs to the Special Issue Practical Application of Functionalized Carbon-Based Nanomaterials)

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12 pages, 3286 KiB

Open AccessReview

Graphene on Silicon Photonics: Light Modulation and Detection for Cutting-Edge Communication Technologies

by Siqi Yan, Jeremy Adcock and Yunhong Ding

Appl. Sci. 2022, 12(1), 313; https://doi.org/10.3390/app12010313 - 29 Dec 2021

Cited by 7 | Viewed by 3586

Abstract

Graphene—a two-dimensional allotrope of carbon in a single-layer honeycomb lattice nanostructure—has several distinctive optoelectronic properties that are highly desirable in advanced optical communication systems. Meanwhile, silicon photonics is a promising solution for the next-generation integrated photonics, owing to its low cost, low propagation [...] Read more.

Graphene—a two-dimensional allotrope of carbon in a single-layer honeycomb lattice nanostructure—has several distinctive optoelectronic properties that are highly desirable in advanced optical communication systems. Meanwhile, silicon photonics is a promising solution for the next-generation integrated photonics, owing to its low cost, low propagation loss and compatibility with CMOS fabrication processes. Unfortunately, silicon’s photodetection responsivity and operation bandwidth are intrinsically limited by its material characteristics. Graphene, with its extraordinary optoelectronic properties has been widely applied in silicon photonics to break this performance bottleneck, with significant progress reported. In this review, we focus on the application of graphene in high-performance silicon photonic devices, including modulators and photodetectors. Moreover, we explore the trend of development and discuss the future challenges of silicon-graphene hybrid photonic devices. Full article

(This article belongs to the Special Issue Practical Application of Functionalized Carbon-Based Nanomaterials)

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28 pages, 4938 KiB

Open AccessFeature PaperReview

Carbon Nanostructures Decorated with Titania: Morphological Control and Applications

by Maria Cristina Cringoli, Siglinda Perathoner, Paolo Fornasiero and Silvia Marchesan

Appl. Sci. 2021, 11(15), 6814; https://doi.org/10.3390/app11156814 - 24 Jul 2021

Cited by 6 | Viewed by 3968

Abstract

Nanostructured titania (TiO₂) is the most widely applied semiconducting oxide for a variety of purposes, and it is found in many commercial products. The vast majority of uses rely on its photo-activity, which, upon light irradiation, results in excited states that [...] Read more.

Nanostructured titania (TiO₂) is the most widely applied semiconducting oxide for a variety of purposes, and it is found in many commercial products. The vast majority of uses rely on its photo-activity, which, upon light irradiation, results in excited states that can be used for diverse applications. These range from catalysis, especially for energy or environmental remediation, to medicine—in particular, to attain antimicrobial surfaces and coatings for titanium implants. Clearly, the properties of titania are enhanced when working at the nanoscale, thanks to the increasingly active surface area. Nanomorphology plays a key role in the determination of the materials’ final properties. In particular, the nucleation and growth of nanosized titania onto carbon nanostructures as a support is a hot topic of investigation, as the nanocarbons not only provide structural stability but also display the ability of electronic communication with the titania, leading to enhanced photoelectronic properties of the final materials. In this concise review, we present the latest progress pertinent to the use of nanocarbons as templates to tailor nanostructured titania, and we briefly review the most promising applications and future trends of this field. Full article

(This article belongs to the Special Issue Practical Application of Functionalized Carbon-Based Nanomaterials)

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19 pages, 4997 KiB

Open AccessFeature PaperReview

Laser Synthesized Graphene and Its Applications

by Vittorio Scardaci

Appl. Sci. 2021, 11(14), 6304; https://doi.org/10.3390/app11146304 - 8 Jul 2021

Cited by 15 | Viewed by 4346

Abstract

Since graphene was discovered, a great deal of research effort has been devoted to finding more and more effective synthetic routes, stimulated by its astounding properties and manifold promising applications. Over the past decade, laser synthesis has been proposed as a viable synthesis [...] Read more.

Since graphene was discovered, a great deal of research effort has been devoted to finding more and more effective synthetic routes, stimulated by its astounding properties and manifold promising applications. Over the past decade, laser synthesis has been proposed as a viable synthesis method to reduce graphene oxide to graphene as well as to obtain graphene from other carbonaceous sources such as polymers or other natural materials. This review first proposes to discuss the various conditions under which graphene is obtained from the reduction of graphene oxide or is induced from other materials using laser sources. After that, a wide range of applications proposed for the obtained materials are discussed. Finally, conclusions are drawn and the author’s perspectives are given. Full article

(This article belongs to the Special Issue Practical Application of Functionalized Carbon-Based Nanomaterials)

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