C | Special Issue : Carbon and Related Composites for Sensors and Energy Storage: Synthesis, Properties, and Application

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20 pages, 5501 KiB

Open AccessArticle

Preferential Stripping Analysis of Post-Transition Metals (In and Ga) at Bi/Hg Films Electroplated on Graphene-Functionalized Graphite Rods

by Nastaran Ghaffari, Nazeem Jahed, Zareenah Abader, Priscilla G. L. Baker and Keagan Pokpas

C 2024, 10(4), 95; https://doi.org/10.3390/c10040095 - 12 Nov 2024

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Abstract

In this study, we introduce a novel electrochemical sensor combining reduced graphene oxide (rGO) sheets with a bismuth–mercury (Bi/Hg) film, electroplated onto pencil graphite electrodes (PGEs) for the high-sensitivity detection of trace amounts of gallium (Ga³⁺) and indium (In³⁺) [...] Read more.

In this study, we introduce a novel electrochemical sensor combining reduced graphene oxide (rGO) sheets with a bismuth–mercury (Bi/Hg) film, electroplated onto pencil graphite electrodes (PGEs) for the high-sensitivity detection of trace amounts of gallium (Ga³⁺) and indium (In³⁺) in water samples using square wave anodic stripping voltammetry (SWASV). The electrochemical modification of PGEs with rGO and bimetallic Bi/Hg films (ERGO-Bi/HgF-PGE) exhibited synergistic effects, enhancing the oxidation signals of Ga and In. Graphene oxide (GO) was accumulated onto PGEs and reduced through cyclic reduction. Key parameters influencing the electroanalytical performance, such as deposition potential, deposition time, and pH, were systematically optimized. The improved adsorption of Ga³⁺ and In³⁺ ions at the Bi/Hg films on the graphene-functionalized electrodes during the preconcentration step significantly enhanced sensitivity, achieving detection limits of 2.53 nmol L⁻¹ for Ga³⁺ and 7.27 nmol L⁻¹ for In³⁺. The preferential accumulation of each post-transition metal, used in transparent displays, to form fused alloys at Bi and Hg films, respectively, is highlighted. The sensor demonstrated effective quantification of Ga³⁺ and In³⁺ in tap water, with detection capabilities well below the USEPA guidelines. This study pioneers the use of bimetallic films to selectively and simultaneously detect the post-transition metals In³⁺ and Ga³⁺, highlighting the role of graphene functionalization in augmenting metal film accumulation on cost-effective graphite rods. Additionally, the combined synergistic effects of Bi/Hg and graphene functionalization have been explored for the first time, offering promising implications for environmental analysis and water quality monitoring. Full article

(This article belongs to the Special Issue Carbon and Related Composites for Sensors and Energy Storage: Synthesis, Properties, and Application)

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24 pages, 5981 KiB

Open AccessArticle

Impact of Dispersive Solvent and Temperature on Supercapacitor Performance of N-Doped Reduced Graphene Oxide

by Ankit Yadav, Rajeev Kumar, Deepu Joseph, Nygil Thomas, Fei Yan and Balaram Sahoo

C 2024, 10(4), 89; https://doi.org/10.3390/c10040089 - 10 Oct 2024

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Abstract

This study evaluates the critical roles of the dispersion medium and temperature during the solvothermal synthesis of nitrogen-doped reduced graphene oxide (NG) for enhancing its performance as an active material in supercapacitor electrodes. Using a fixed volume of a solvent (THF, ethanol, acetonitrile, [...] Read more.

This study evaluates the critical roles of the dispersion medium and temperature during the solvothermal synthesis of nitrogen-doped reduced graphene oxide (NG) for enhancing its performance as an active material in supercapacitor electrodes. Using a fixed volume of a solvent (THF, ethanol, acetonitrile, water, N,N-Dimethylformamide, ethylene glycol, or N-Methyl-2-pyrrolidone) as the dispersive medium, a series of samples at different temperatures (60, 75, 95, 120, 150, 180, and 195 °C) are synthesized and investigated. A proper removal of the oxygen moieties from their surface and an optimum number of N-based defects are essential for a better reduction of graphene oxide and better stacking of the NG sheets. The origin of the supercapacitance of NG sheets can be correlated to the inherent properties such as the boiling point, viscosity, dipole moment, and dielectric constant of all the studied solvents, along with the synthesis temperature. Due to the achievement of a suitable synthesis environment, NG synthesized using N,N-Dimethylformamide at 150 °C displays an excellent supercapacitance value of 514 F/g at 0.5 A/g, which is the highest among all our samples and also competitive among several state-of-the-art lightweight carbon materials. Our work not only helps in understanding the origin of the supercapacitance exhibited by graphene-based materials but also tuning them through a suitable choice of synthesis conditions. Full article

(This article belongs to the Special Issue Carbon and Related Composites for Sensors and Energy Storage: Synthesis, Properties, and Application)

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14 pages, 5675 KiB

Open AccessArticle

A Novel Non-Enzymatic Efficient H₂O₂ Sensor Utilizing δ-FeOOH and Prussian Blue Anchoring on Carbon Felt Electrode

by Karoline S. Nantes, Ana L. H. K. Ferreira, Marcio C. Pereira, Francisco G. E. Nogueira and André S. Afonso

C 2024, 10(3), 82; https://doi.org/10.3390/c10030082 - 9 Sep 2024

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Abstract

In this study, an efficient H₂O₂ sensor was developed based on electrochemical Prussian blue (PB) synthesized from the acid suspension of δ-FeOOH and K₃[Fe(CN)₆] using cyclic voltammetry (CV) and anchored on carbon felt (CF), yielding an [...] Read more.

In this study, an efficient H₂O₂ sensor was developed based on electrochemical Prussian blue (PB) synthesized from the acid suspension of δ-FeOOH and K₃[Fe(CN)₆] using cyclic voltammetry (CV) and anchored on carbon felt (CF), yielding an enhanced CF/PB-FeOOH electrode for sensing of H₂O₂ in pH-neutral solution. CF/PB-FeOOH electrode construction was proved by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and X-ray diffraction (XRD), and electrochemical properties were verified by impedance electrochemical and CV. The synergy of δ-FeOOH and PB coupled to CF increases electrocatalytic activity toward H₂O_2, with the sensor showing a linear range of 1.2 to 300 μM and a limit of detection of 0.36 μM. Notably, the CF/PB-FeOOH electrode exhibited excellent selectivity for H₂O₂ detection in the presence of dopamine (DA), uric acid (UA), and ascorbic acid (AA). The calculated H₂O₂ recovery rates varied between 93% and 101% in fetal bovine serum diluted in PBS. This work underscores the potential of CF/PB-FeOOH electrodes in progressing electrochemical sensing technologies for various biological and environmental applications. Full article

(This article belongs to the Special Issue Carbon and Related Composites for Sensors and Energy Storage: Synthesis, Properties, and Application)

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11 pages, 2769 KiB

Open AccessArticle

A Nitrogen/Oxygen Dual-Doped Porous Carbon with High Catalytic Conversion Ability toward Polysulfides for Advanced Lithium–Sulfur Batteries

by Xiaoyan Shu, Yuanjiang Yang, Zhongtang Yang, Honghui Wang and Nengfei Yu

C 2024, 10(3), 67; https://doi.org/10.3390/c10030067 - 30 Jul 2024

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Abstract

Lithium–sulfur batteries (LSBs) have attracted widespread attention due to their high theoretical energy density and low cost. However, their development has been constrained by the shuttle effect of lithium polysulfides and their slow reaction kinetics. In this work, a nitrogen/oxygen dual-doped porous carbon [...] Read more.

Lithium–sulfur batteries (LSBs) have attracted widespread attention due to their high theoretical energy density and low cost. However, their development has been constrained by the shuttle effect of lithium polysulfides and their slow reaction kinetics. In this work, a nitrogen/oxygen dual-doped porous carbon (N/O-PC) was synthesized by annealing the precursor of zeolitic imidazolate framework-8 grown in situ on MWCNTs (ZIF-8/MWCNTs). Then, the N/O-PC composite served as an efficient host for LSBs through chemical adsorption and providing catalytic conversion sites of polysulfides. Moreover, the interconnected porous carbon-based structure facilitates electron and ion transfer. Thus, the S/N/O-PC cathode exhibits high cycling stability (a stable capacity of 685.9 mA h g⁻¹ at 0.2 C after 100 cycles). It also demonstrates excellent rate performance with discharge capacities of 1018.2, 890.2, 775.1, 722.7, 640.4, and 579.6 mAh g⁻¹ at 0.2, 0.5, 1.0, 2.0, 3.0, and 5.0 C, respectively. This work provides an effective strategy for designing and developing high energy density, long cycle life LSBs. Full article

(This article belongs to the Special Issue Carbon and Related Composites for Sensors and Energy Storage: Synthesis, Properties, and Application)

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23 pages, 6557 KiB

Open AccessArticle

FeS₂ Nanoparticles in S-Doped Carbon: Ageing Effects on Performance as a Supercapacitor Electrode

by Sirine Zallouz, Bénédicte Réty, Jean-Marc Le Meins, Mame Youssou Ndiaye, Philippe Fioux and Camélia Matei Ghimbeu

C 2023, 9(4), 112; https://doi.org/10.3390/c9040112 - 17 Nov 2023

Cited by 2 | Viewed by 2181

Abstract

Although transition metal sulfides have prodigious potential for use as electrode materials because of their low electronegativities, their large volume changes inhibit broad application. Moreover, there is only limited knowledge of the ageing processes of these materials at the nanoscale. Herein, nano-C/FeS₂ [...] Read more.

Although transition metal sulfides have prodigious potential for use as electrode materials because of their low electronegativities, their large volume changes inhibit broad application. Moreover, there is only limited knowledge of the ageing processes of these materials at the nanoscale. Herein, nano-C/FeS₂ materials were prepared via one-pot syntheses from green biodegradable carbon precursors, followed by activation and sulfidation. The increased activation/sulfidation time led to an increase in the size of the nanoparticles (7 to 17 nm) and their aggregation, as well as in an increase in the specific surface area. The materials were then used as electrodes in 2-electrode symmetric supercapacitors with 2 M KOH. The activation process resulted in improved capacitance (60 F g⁻¹ at 0.1 A g⁻¹) and rate capability (36%) depending on the composite porosity, conductivity, and size of the FeS₂ particles. The ageing of the FeS₂ nanoparticles was investigated under air, and a progressive transformation of the nano-FeS₂ into hydrated iron hydroxy sulfate with a significant morphological modification was observed, resulting in drastic decreases in the capacitance (70%) and retention. In contrast, the ageing of nano-FeS₂ during cycling led to the formation of a supplementary iron oxyhydroxide phase, which contributed to the enhanced capacitance (57%) and long-term cycling (132% up to 10,000 cycles) of the device. Full article

(This article belongs to the Special Issue Carbon and Related Composites for Sensors and Energy Storage: Synthesis, Properties, and Application)

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12 pages, 3855 KiB

Open AccessArticle

Synthesis and Characterization of Ni–Co–O Nanosheets on Silicon Carbide Microspheres/Graphite Composite for Supercapacitor Applications

by Han-Wei Chang, Zong-Ying Tsai, Jia-Jun Ye, Kuo-Chuang Chiu, Tzu-Yu Liu and Yu-Chen Tsai

C 2023, 9(4), 101; https://doi.org/10.3390/c9040101 - 29 Oct 2023

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Abstract

The well-interconnected ternary Ni–Co–O nanosheets were grown on silicon carbide microspheres/graphite composite (gra@SiC/Ni–Co–O) by optimizing the electrodeposition method. Silicon carbide microspheres/graphite composite (gra@SiC) serves as a conductive template for the growth of Ni–Co–O nanosheets to form a binder-free 3D well-designed hierarchical interconnected network [...] Read more.

The well-interconnected ternary Ni–Co–O nanosheets were grown on silicon carbide microspheres/graphite composite (gra@SiC/Ni–Co–O) by optimizing the electrodeposition method. Silicon carbide microspheres/graphite composite (gra@SiC) serves as a conductive template for the growth of Ni–Co–O nanosheets to form a binder-free 3D well-designed hierarchical interconnected network between the Ni–Co–O nanosheets and SiC microspheres. The obtained gra@SiC/Ni–Co–O is proposed as a great capacitance performance for supercapacitors. Field emission scanning electron microscopy (FESEM), Raman spectroscopy, high-resolution transmission electron microscopy (HRTEM) with selected area electron diffraction (SAED) and energy dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy, and electrochemical analysis were employed to investigate the morphology and structural and electrochemical characteristics. The synergistic effects of EDLC (SiC microspheres) and pseudo-capacitance (Ni–Co–O nanosheets) can effectively improve the supercapacitive performance. It is also worth mentioning that after electrochemical testing, the redox reaction of Ni–Co–O nanosheets greatly promoted the faradic pseudo-capacitance contribution, and silicon carbide microspheres/graphite composite contributed to the formation of a 3D interconnected network, improving the cycling stability during the charging/discharging processes. Full article

(This article belongs to the Special Issue Carbon and Related Composites for Sensors and Energy Storage: Synthesis, Properties, and Application)

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17 pages, 6900 KiB

Open AccessArticle

Chemical Activation of Apricot Pit-Derived Carbon Sorbents for the Effective Removal of Dyes in Environmental Remediation

by Vitalii Vashchynskyi, Olena Okhay and Tetiana Boychuk

C 2023, 9(4), 93; https://doi.org/10.3390/c9040093 - 29 Sep 2023

Cited by 4 | Viewed by 1540

Abstract

The aim of this work is to study the properties of carbon materials prepared from apricot stones by carbonization at 300–900 °C and chemical activation by KOH with different ratios between components. It was found that increasing the carbonization temperature to 800–900 °C [...] Read more.

The aim of this work is to study the properties of carbon materials prepared from apricot stones by carbonization at 300–900 °C and chemical activation by KOH with different ratios between components. It was found that increasing the carbonization temperature to 800–900 °C leads to the degradation of narrow micropores and the carbon matrix. The adsorbent materials were characterized with FTIR and SEM, and a specific surface area was calculated. Moreover, additional activation by HNO₃ and annealing at 450 °C led to an increase in surface area up to 1300 m²/g. The obtained N-enriched sorbents show adsorption activities of 190–235 mg/g for methylene blue and 210–260 mg/g for methyl orange. The results of this study can be useful for future scale-up using the apricot material as a low-cost adsorbent for the removal of dyes in environmental remediation production. Full article

(This article belongs to the Special Issue Carbon and Related Composites for Sensors and Energy Storage: Synthesis, Properties, and Application)

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20 pages, 3649 KiB

Open AccessArticle

Impacts of Mn Content and Mass Loading on the Performance of Flexible Asymmetric Solid-State Supercapacitors Using Mixed-Phase MnO₂/N-Containing Graphene Composites as Cathode Materials

by Hsin-Ya Chiu and Chun-Pei Cho

C 2023, 9(3), 88; https://doi.org/10.3390/c9030088 - 10 Sep 2023

Cited by 1 | Viewed by 2025

Abstract

MnO₂/nitrogen-containing graphene (x-NGM) composites with varying contents of Mn were used as the electrode materials for flexible asymmetric solid-state supercapacitors. The MnO₂ was a two-phase mixture of γ- and α-MnO₂. The combination of nitrogen-containing graphene and MnO₂ [...] Read more.

MnO₂/nitrogen-containing graphene (x-NGM) composites with varying contents of Mn were used as the electrode materials for flexible asymmetric solid-state supercapacitors. The MnO₂ was a two-phase mixture of γ- and α-MnO₂. The combination of nitrogen-containing graphene and MnO₂ improved reversible Faraday reactions and charge transfer. However, excessive MnO₂ reduced conductivity, hindering ion diffusion and charge transfer. Overloading the electrode with active materials also negatively affected conductivity. Both the mass loading and MnO₂ content were crucial to electrochemical performance. x-NGM composites served as cathode materials, while graphene acted as the anode material. Operating by two charge storage mechanisms enabled a synergistic effect, resulting in better charge storage purposes. Among the supercapacitors, the 3-NGM1//G1 exhibited the highest conductivity, efficient charge transfer, and superior capacitive characteristics. It showed a superior specific capacitance of 579 F·g⁻¹, leading to high energy density and power density. Flexible solid-state supercapacitors using x-NGM composites demonstrated good cycle stability, with a high capacitance retention rate of 86.7% after 2000 bending cycles. Full article

(This article belongs to the Special Issue Carbon and Related Composites for Sensors and Energy Storage: Synthesis, Properties, and Application)

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17 pages, 3888 KiB

Open AccessArticle

Phosphorus/Sulfur-Enriched Reduced Graphene Oxide Papers Obtained from Recycled Graphite: Solid-State NMR Characterization and Electrochemical Performance for Energy Storage

by Mariana A. Vieira, Tainara L. G. Costa, Gustavo R. Gonçalves, Daniel F. Cipriano, Miguel A. Schettino, Jr., Elen L. da Silva, Andrés Cuña and Jair C. C. Freitas

C 2023, 9(2), 60; https://doi.org/10.3390/c9020060 - 12 Jun 2023

Cited by 1 | Viewed by 2086

Abstract

The reduction of graphene oxide (GO) by means of thermal and/or chemical treatments leads to the production of reduced graphene oxide (rGO)—a material with improved electrical conductivity and considered a viable and low-cost alternative to pure graphene in several applications, including the production [...] Read more.

The reduction of graphene oxide (GO) by means of thermal and/or chemical treatments leads to the production of reduced graphene oxide (rGO)—a material with improved electrical conductivity and considered a viable and low-cost alternative to pure graphene in several applications, including the production of supercapacitor electrodes. In the present work, GO was prepared by the oxidation of graphite recycled from spent Li-ion batteries using mixtures of sulfuric and phosphoric acids (with different H₂SO₄/H₃PO₄ ratios), leading to the production of materials with significant S and P contents. These materials were then thermally reduced, resulting in rGO papers that were investigated by solid-state ¹³C and ³¹P nuclear magnetic resonance, along with other methods. The electrochemical properties of the produced rGO papers were evaluated, including the recording of cyclic voltammetry and galvanostatic charge–discharge curves, besides electrochemical impedance spectroscopy analyses. The samples obtained by thermal reduction at 150 °C exhibited good rate capability at high current density and high capacitance retention after a large number of charge–discharge cycles. The results evidenced a strong relationship between the electrochemical properties of the produced materials and their chemical and structural features, especially for the samples containing both S and P elements. The methods described in this work represent, then, a facile and low-cost alternative for the production of rGO papers using graphite recycled from spent batteries, with promising applications as supercapacitor electrodes. Full article

(This article belongs to the Special Issue Carbon and Related Composites for Sensors and Energy Storage: Synthesis, Properties, and Application)

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20 pages, 3025 KiB

Open AccessArticle

Hands-On Quantum Sensing with NV⁻ Centers in Diamonds

by J. L. Sánchez Toural, V. Marzoa, R. Bernardo-Gavito, J. L. Pau and D. Granados

C 2023, 9(1), 16; https://doi.org/10.3390/c9010016 - 29 Jan 2023

Viewed by 7616

Abstract

The physical properties of diamond crystals, such as color or electrical conductivity, can be controlled via impurities. In particular, when doped with nitrogen, optically active nitrogen-vacancy centers (

N V

), can be induced. The center is an outstanding quantum spin system that [...] Read more.

The physical properties of diamond crystals, such as color or electrical conductivity, can be controlled via impurities. In particular, when doped with nitrogen, optically active nitrogen-vacancy centers (

N V

), can be induced. The center is an outstanding quantum spin system that enables, under ambient conditions, optical initialization, readout, and coherent microwave control with applications in sensing and quantum information. Under optical and radio frequency excitation, the Zeeman splitting of the degenerate states allows the quantitative measurement of external magnetic fields with high sensitivity. This study provides a pedagogical introduction to the properties of the

N V

centers as well as a step-by-step process to develop and test a simple magnetic quantum sensor based on color centers with significant potential for the development of highly compact multisensor systems. Full article

(This article belongs to the Special Issue Carbon and Related Composites for Sensors and Energy Storage: Synthesis, Properties, and Application)

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13 pages, 2203 KiB

Open AccessArticle

Carbon Dots versus Nano-Carbon/Organic Hybrids—Divergence between Optical Properties and Photoinduced Antimicrobial Activities

by Audrey F. Adcock, Ping Wang, Elton Y. Cao, Lin Ge, Yongan Tang, Isaiah S. Ferguson, Fares S. Abu Sweilem, Lauren Petta, William Cannon, Liju Yang, Christopher E. Bunker and Ya-Ping Sun

C 2022, 8(4), 54; https://doi.org/10.3390/c8040054 - 20 Oct 2022

Cited by 3 | Viewed by 2985

Abstract

Carbon dots (CDots) are generally defined as small-carbon nanoparticles with surface organic functionalization and their classical synthesis is literally the functionalization of preexisting carbon nanoparticles. Other than these “classically defined CDots”, however, the majority of the dot samples reported in the literature were [...] Read more.

Carbon dots (CDots) are generally defined as small-carbon nanoparticles with surface organic functionalization and their classical synthesis is literally the functionalization of preexisting carbon nanoparticles. Other than these “classically defined CDots”, however, the majority of the dot samples reported in the literature were prepared by thermal carbonization of organic precursors in mostly “one-pot” processing. In this work, thermal processing of the selected precursors intended for carbonization was performed with conditions of 200 °C for 3 h, 330 °C for 6 h, and heating by microwave irradiation, yielding samples denoted as CS200, CS330, and CS_MT, respectively. These samples are structurally different from the classical CDots and should be considered as “nano-carbon/organic hybrids”. Their optical spectroscopic properties were found comparable to those of the classical CDots, but very different in the related photoinduced antibacterial activities. Mechanistic origins of the divergence were explored, with the results suggesting major factors associated with the structural and morphological characteristics of the hybrids. Full article

(This article belongs to the Special Issue Carbon and Related Composites for Sensors and Energy Storage: Synthesis, Properties, and Application)

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14 pages, 3132 KiB

Open AccessArticle

Easy and Low-Cost Method for Synthesis of Carbon–Silica Composite from Vinasse and Study of Ibuprofen Removal

by Yuvarat Ngernyen, Thitipong Siriketh, Kritsada Manyuen, Panta Thawngen, Wipha Rodtoem, Kritiyaporn Wannuea, Jesper T. N. Knijnenburg and Supattra Budsaereechai

C 2022, 8(4), 51; https://doi.org/10.3390/c8040051 - 7 Oct 2022

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Abstract

Vinasse was successfully utilized to synthesize carbon–silica composite with a low-cost silica source available in Thailand (sodium silicate, Na₂SiO₃) and most commonly used source, tetraethyl orthosilicate (TEOS). The composites were prepared by a simple one-step sol–gel process by varying [...] Read more.

Vinasse was successfully utilized to synthesize carbon–silica composite with a low-cost silica source available in Thailand (sodium silicate, Na₂SiO₃) and most commonly used source, tetraethyl orthosilicate (TEOS). The composites were prepared by a simple one-step sol–gel process by varying the vinasse (as carbon source) to silica source (Na₂SiO₃ or TEOS) weight ratio. The resulting composites were characterized by N₂ adsorption, moisture and ash contents, pH, pH_pzc, bulk density, Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and scanning electron microscopy-energy dispersive X-ray analysis (SEM-EDX). The composites had highest surface area of 313 and 456 m²/g, with average mesopore diameters of 5.00 and 2.62 nm when using Na₂SiO₃ and TEOS as the silica sources, respectively. The adsorption of a non-steroidal anti-inflammatory drug, ibuprofen, was investigated. The contact time to reach equilibrium was 60 min for both composites. The adsorption kinetics were fitted by a pseudo-second-order model with the correlation coefficient R² > 0.997. The adsorption isotherms were well described by the Langmuir model (R² > 0.992), which indicates monolayer adsorption. The maximal adsorption capacities of the Na₂SiO₃- and TEOS-based composites were as high as 406 and 418 mg/g at pH 2, respectively. The research results indicate that vinasse and a low-cost silica source (Na₂SiO₃) show great potential to synthesize adsorbents through a simple method with high efficiency. Full article

(This article belongs to the Special Issue Carbon and Related Composites for Sensors and Energy Storage: Synthesis, Properties, and Application)

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9 pages, 2783 KiB

Open AccessArticle

Synthesis of Graphene Quantum Dots by a Simple Hydrothermal Route Using Graphite Recycled from Spent Li-Ion Batteries

by Lyane M. Darabian, Tainara L. G. Costa, Daniel F. Cipriano, Carlos W. Cremasco, Miguel A. Schettino, Jr. and Jair C. C. Freitas

C 2022, 8(4), 48; https://doi.org/10.3390/c8040048 - 22 Sep 2022

Cited by 4 | Viewed by 2787

Abstract

Graphene quantum dots (GQDs) are nanosized systems that combine beneficial properties typical of graphenic materials (such as chemical stability, biocompatibility and ease of preparation from low-cost precursors) with remarkable photoluminescent features. GQDs are well-known for their low cytotoxicity and for being promising candidates [...] Read more.

Graphene quantum dots (GQDs) are nanosized systems that combine beneficial properties typical of graphenic materials (such as chemical stability, biocompatibility and ease of preparation from low-cost precursors) with remarkable photoluminescent features. GQDs are well-known for their low cytotoxicity and for being promising candidates in applications, such as bioimaging, optoelectronics, electrochemical energy storage, sensing and catalysis, among others. This work describes a simple and low-cost synthesis of GQDs, starting from an alcoholic aqueous suspension of graphene oxide (GO) and using a hydrothermal route. GO was prepared using graphite recycled from spent Li-ion batteries, via a modified Hummers method. The GO suspension was submitted to hydrothermal treatments at different temperatures using a homemade hydrothermal reactor that allows the control of the heating program and the assessment of the internal pressure generated in the reaction. The synthesized GQDs exhibited bright blue/green luminescence under UV light; showing the success of the chosen route and opening the way for future applications of these materials in the field of optoelectronic devices. Full article

(This article belongs to the Special Issue Carbon and Related Composites for Sensors and Energy Storage: Synthesis, Properties, and Application)

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17 pages, 26314 KiB

Open AccessArticle

Investigation of Electron Transfer Mechanistic Pathways of Ferrocene Derivatives in Droplet at Carbon Electrode

by Sidra Ayaz, Afzal Shah and Shamsa Munir

C 2022, 8(3), 45; https://doi.org/10.3390/c8030045 - 9 Sep 2022

Cited by 3 | Viewed by 2872

Abstract

The results of cyclic, differential pulse and square wave voltammetric studies of four ferrocene derivatives, i.e., 4-ferrocenyl-3-methyl aniline (FMA), 3-Chloro-4-ferrocenyl aniline (CFA), 4-ferrocenyl aniline (FA) and ferrocenyl benzoic acid (FBA) on carbon electrode, revealed that the redox behavior of these compounds is [...] Read more.

The results of cyclic, differential pulse and square wave voltammetric studies of four ferrocene derivatives, i.e., 4-ferrocenyl-3-methyl aniline (FMA), 3-Chloro-4-ferrocenyl aniline (CFA), 4-ferrocenyl aniline (FA) and ferrocenyl benzoic acid (FBA) on carbon electrode, revealed that the redox behavior of these compounds is sensitive to pH, concentration, scan number and scan rate. One electron, diffusion controlled, with a quasi-reversible redox signal displaying ferrocene/ferrocenium couple was observed for each of the studied ferrocenyl derivatives. Quasi-reversibility of this signal is evidenced by ∆E_p, I_a/I_c current ratio and k_sh values. Another one electron and one proton irreversible oxidation signal was noticed in the voltammograms of these compounds except FBA. This signal corresponds to the electro-oxidation of the amine group and its irreversibility, as supported by ∆E_p, I_a/I_c current ratio and k_sh values, is due to the influence of the electron donating nature of the amine group. A number of electrochemical parameters such as D, k_sh, LOD and LOQ were evaluated for the targeted ferrocene derivatives. The obtained parameters are expected to provide insights into the redox mechanism for understanding their biochemical actions. The electrochemistry presented in this work is done using a unique environmentally benign and cost-effective droplet electrochemical approach. Full article

(This article belongs to the Special Issue Carbon and Related Composites for Sensors and Energy Storage: Synthesis, Properties, and Application)

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14 pages, 4311 KiB

Open AccessArticle

Power Generation Characteristics of Polymer Electrolyte Fuel Cells Using Carbon Nanowalls as Catalyst Support Material

by Takayuki Ohta, Hiroaki Iwata, Mineo Hiramatsu, Hiroki Kondo and Masaru Hori

C 2022, 8(3), 44; https://doi.org/10.3390/c8030044 - 27 Aug 2022

Cited by 4 | Viewed by 3026

Abstract

We evaluated the power generation characteristics of a polymer electrolyte fuel cell (PEFC) composed of Pt-supported carbon nanowalls (CNWs) and a microporous layer (MPL) of carbon black on carbon paper (CP) as catalyst support materials. CNWs, standing vertically on highly crystallizing graphene sheets, [...] Read more.

We evaluated the power generation characteristics of a polymer electrolyte fuel cell (PEFC) composed of Pt-supported carbon nanowalls (CNWs) and a microporous layer (MPL) of carbon black on carbon paper (CP) as catalyst support materials. CNWs, standing vertically on highly crystallizing graphene sheets, were synthesized on an MPL/CP by plasma-enhanced chemical vapor deposition (PECVD) using inductively coupled plasma (ICP). Pt nanoparticles were supported on the CNW surface using the liquid-phase reduction method. The three types of voltage loss, namely those due to activated polarization, resistance polarization, and diffusion polarization, are discussed for the power generation characteristics of the PEFC using the Pt/CNWs/MPL/CP. The relationship between the height or gap area of the CNWs and the voltage loss of the PEFC is demonstrated, whereby the CNW height increased with the extension of growth time. The three-phase interface area increased with the increase in the CNW height, resulting in mitigation of the loss due to activated polarization. The gap area of the CNWs varied when changing the CH₄/H₂ gas ratio. The loss due to diffusion polarization was reduced by enlarging the gap area, due to the increased diffusion of fuel gas and discharge of water. The secondary growth of the CNWs caused the three-phase interface area to decrease as a result of platinum aggregation, impedance of the supply of ionomer dispersion solution to the bottom of the CNWs, and inhibition of fuel gas and water diffusion, which led to the loss of activated and diffuse polarizations. The voltage losses can be mitigated by increasing the height of CNWs while avoiding secondary growth. Full article

(This article belongs to the Special Issue Carbon and Related Composites for Sensors and Energy Storage: Synthesis, Properties, and Application)

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14 pages, 4117 KiB

Open AccessArticle

Development of Disposable and Flexible Supercapacitor Based on Carbonaceous and Ecofriendly Materials

by Giovanni G. Daniele, Daniel C. de Souza, Paulo Roberto de Oliveira, Luiz O. Orzari, Rodrigo V. Blasques, Rafael L. Germscheidt, Emilly C. da Silva, Leandro A. Pocrifka, Juliano A. Bonacin and Bruno C. Janegitz

C 2022, 8(2), 32; https://doi.org/10.3390/c8020032 - 7 Jun 2022

Cited by 3 | Viewed by 3042

Abstract

A novel flexible supercapacitor device was developed from a polyethylene terephthalate substrate, reused from beverage bottles, and a conductive ink based on carbon black (CB) and cellulose acetate (CA). The weight composition of the conductive ink was evaluated to determine the best mass [...] Read more.

A novel flexible supercapacitor device was developed from a polyethylene terephthalate substrate, reused from beverage bottles, and a conductive ink based on carbon black (CB) and cellulose acetate (CA). The weight composition of the conductive ink was evaluated to determine the best mass percentage ratio between CB and CA in terms of capacitive behavior. The evaluation was performed by using different electrochemical techniques: cyclic voltammetry, obtaining the highest capacitance value for the device with the 66.7/33.3 wt% CB/CA in a basic H₂SO₄ solution, reaching 135.64 F g⁻¹. The device was applied in potentiostatic charge/discharge measurements, achieving values of 2.45 Wh kg⁻¹ for specific energy and around 1000 W kg⁻¹ for specific power. Therefore, corroborated with electrochemical impedance spectroscopy assays, the relatively low-price proposed device presented a suitable performance for application as supercapacitors, being manufactured from reused materials, contributing to the energy storage field enhancement. Full article

(This article belongs to the Special Issue Carbon and Related Composites for Sensors and Energy Storage: Synthesis, Properties, and Application)

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37 pages, 5769 KiB

Open AccessReview

A Review of Carbon Nanotubes, Graphene and Nanodiamond Based Strain Sensor in Harsh Environments

by Xiaoyan Wang, Eng Gee Lim, Kai Hoettges and Pengfei Song

C 2023, 9(4), 108; https://doi.org/10.3390/c9040108 - 14 Nov 2023

Cited by 6 | Viewed by 3962

Abstract

Flexible and wearable electronics have attracted significant attention for their potential applications in wearable human health monitoring, care systems, and various industrial sectors. The exploration of wearable strain sensors in diverse application scenarios is a global issue, shaping the future of our intelligent [...] Read more.

Flexible and wearable electronics have attracted significant attention for their potential applications in wearable human health monitoring, care systems, and various industrial sectors. The exploration of wearable strain sensors in diverse application scenarios is a global issue, shaping the future of our intelligent community. However, current state-of-the-art strain sensors still encounter challenges, such as susceptibility to interference under humid conditions and vulnerability to chemical and mechanical fragility. Carbon materials offer a promising solution due to their unique advantages, including excellent electrical conductivity, intrinsic and structural flexibility, lightweight nature, high chemical and thermal stability, ease of chemical functionalization, and potential for mass production. Carbon-based materials, such as carbon nanotubes, graphene, and nanodiamond, have been introduced as strain sensors with mechanical and chemical robustness, as well as water repellency functionality. This review reviewed the ability of carbon nanotubes-, graphene-, and nanodiamond-based strain sensors to withstand extreme conditions, their sensitivity, durability, response time, and diverse applications, including strain/pressure sensors, temperature/humidity sensors, and power devices. The discussion highlights the promising features and potential advantages offered by these carbon materials in strain sensing applications. Additionally, this review outlines the existing challenges in the field and identifies future opportunities for further advancement and innovation. Full article

(This article belongs to the Special Issue Carbon and Related Composites for Sensors and Energy Storage: Synthesis, Properties, and Application)

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30 pages, 8911 KiB

Open AccessFeature PaperEditor’s ChoiceReview

Carbon Fibers: From PAN to Asphaltene Precursors; A State-of-Art Review

by Hossein Bisheh and Yasmine Abdin

C 2023, 9(1), 19; https://doi.org/10.3390/c9010019 - 4 Feb 2023

Cited by 11 | Viewed by 9142

Abstract

Due to their outstanding material properties, carbon fibers are widely used in various industrial applications as functional or structural materials. This paper reviews the material properties and use of carbon fiber in various applications and industries and compares it with other existing fillers [...] Read more.

Due to their outstanding material properties, carbon fibers are widely used in various industrial applications as functional or structural materials. This paper reviews the material properties and use of carbon fiber in various applications and industries and compares it with other existing fillers and reinforcing fibers. The review also examines the processing of carbon fibers and the main challenges in their fabrication. At present, two main precursors are primarily utilized to produce carbon fibers, i.e., polyacrylonitrile (PAN) and petroleum pitch. Each of these precursors makes carbon fibers with different properties. However, due to the costly and energy-intensive processes of carbon fiber production based on the existing precursors, there is an increasingly growing need to introduce cheaper precursors to compete with other fibers on the market. A special focus will be given to the most recent development of manufacturing more sustainable and cost-effective carbon fibers derived from petroleum asphaltenes. This review paper demonstrates that low-cost asphaltene-based carbon fibers can be a substitute for costly PAN/pitch-based carbon fibers at least for functional applications. The value proposition, performance/cost advantages, potential market, and market size as well as processing challenges and methods for overcoming these will be discussed. Full article

(This article belongs to the Special Issue Carbon and Related Composites for Sensors and Energy Storage: Synthesis, Properties, and Application)

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19 pages, 3793 KiB

Open AccessReview

Recent Advances on Capacitive Proximity Sensors: From Design and Materials to Creative Applications

by Reza Moheimani, Paniz Hosseini, Saeed Mohammadi and Hamid Dalir

C 2022, 8(2), 26; https://doi.org/10.3390/c8020026 - 5 May 2022

Cited by 25 | Viewed by 12436

Abstract

Capacitive proximity sensors (CPSs) have recently been a focus of increased attention because of their widespread applications, simplicity of design, low cost, and low power consumption. This mini review article provides a comprehensive overview of various applications of CPSs, as well as current [...] Read more.

Capacitive proximity sensors (CPSs) have recently been a focus of increased attention because of their widespread applications, simplicity of design, low cost, and low power consumption. This mini review article provides a comprehensive overview of various applications of CPSs, as well as current advancements in CPS construction approaches. We begin by outlining the major technologies utilized in proximity sensing, highlighting their characteristics and applications, and discussing their advantages and disadvantages, with a heavy emphasis on capacitive sensors. Evaluating various nanocomposites for proximity sensing and corresponding detecting approaches ranging from physical to chemical detection are emphasized. The matrix and active ingredients used in such sensors, as well as the measured ranges, will also be discussed. A good understanding of CPSs is not only essential for resolving issues, but is also one of the primary forces propelling CPS technology ahead. We aim to examine the impediments and possible solutions to the development of CPSs. Furthermore, we illustrate how nanocomposite fusion may be used to improve the detection range and accuracy of a CPS while also broadening the application scenarios. Finally, the impact of conductance on sensor performance and other variables that impact the sensitivity distribution of CPSs are presented. Full article

(This article belongs to the Special Issue Carbon and Related Composites for Sensors and Energy Storage: Synthesis, Properties, and Application)

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