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18 pages, 2662 KiB

Open AccessArticle

DFT-Based Studies on Carbon Adsorption on the wz-GaN Surfaces and the Influence of Point Defects on the Stability of the Diamond–GaN Interfaces

by Malgorzata Sznajder and Roman Hrytsak

Materials 2021, 14(21), 6532; https://doi.org/10.3390/ma14216532 - 29 Oct 2021

Cited by 1 | Viewed by 2416

Abstract

Integration of diamond with GaN-based high-electron-mobility transistors improves thermal management, influencing the reliability, performance, and lifetime of GaN-based devices. The current GaN-on-diamond integration technology requires precise interface engineering and appropriate interfacial layers. In this respect, we performed first principles calculation on the stability [...] Read more.

Integration of diamond with GaN-based high-electron-mobility transistors improves thermal management, influencing the reliability, performance, and lifetime of GaN-based devices. The current GaN-on-diamond integration technology requires precise interface engineering and appropriate interfacial layers. In this respect, we performed first principles calculation on the stability of diamond–GaN interfaces in the framework of density functional theory. Initially, some stable adsorption sites of C atoms were found on the Ga- and N-terminated surfaces that enabled the creation of a flat carbon monolayer. Following this, a model of diamond–GaN heterojunction with the growth direction [111] was constructed based on carbon adsorption results on GaN{0001} surfaces. Finally, we demonstrate the ways of improving the energetic stability of diamond–GaN interfaces by means of certain reconstructions induced by substitutional dopants present in the topmost GaN substrate’s layer. Full article

(This article belongs to the Special Issue New Findings in Carbon-Based Materials: From Functionalization to Applications)

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16 pages, 3847 KiB

Open AccessArticle

Analysis of Selected Methods Use for Calculation of the Coefficients of Adsorption Isotherms and Simplified Equations of Adsorption Dynamics with the Use of IZO Application

by Jacek Piekarski, Katarzyna Ignatowicz and Tomasz Dąbrowski

Materials 2021, 14(15), 4192; https://doi.org/10.3390/ma14154192 - 27 Jul 2021

Cited by 8 | Viewed by 2322

Abstract

The purpose of this paper is to present the IZO application that calculates and visualizes coefficients of adsorption isotherms according to Freundlich, Langmuir, and BET in a classic and linear system, in a simple communicative way. The application also calculates the working time [...] Read more.

The purpose of this paper is to present the IZO application that calculates and visualizes coefficients of adsorption isotherms according to Freundlich, Langmuir, and BET in a classic and linear system, in a simple communicative way. The application also calculates the working time of the adsorption bed based on the transformation of the mass balance equation, and according to the Zuchowicki, Zabieziński, Tichonow, and the Bohart-Adams equations. The laboratory tests of the adsorption process of leachate from a municipal landfill on selected active coals ORGANOSORB 10, DESOTEK, and BA-10, were conducted to check the program for accuracy. Results of tests confirm that the linearization method of the calculation of adsorption isotherms coefficients, used in the IZO application, gives sufficient accuracy and may be used as an alternative of, e.g., the nonlinear estimation method. Full article

(This article belongs to the Special Issue New Findings in Carbon-Based Materials: From Functionalization to Applications)

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14 pages, 2751 KiB

Open AccessArticle

New Insight into the Fluorescence Quenching of Nitrogen-Containing Carbonaceous Quantum Dots—From Surface Chemistry to Biomedical Applications

by Marek Wiśniewski, Joanna Czarnecka, Paulina Bolibok, Michał Świdziński and Katarzyna Roszek

Materials 2021, 14(9), 2454; https://doi.org/10.3390/ma14092454 - 9 May 2021

Cited by 14 | Viewed by 3112

Abstract

Carbon-based quantum dots are widely suggested as fluorescent carriers of drugs, genes or other bioactive molecules. In this work, we thoroughly examine the easy-to-obtain, biocompatible, nitrogen-containing carbonaceous quantum dots (N-CQDs) with stable fluorescent properties that are resistant to wide-range pH changes. Moreover, we [...] Read more.

Carbon-based quantum dots are widely suggested as fluorescent carriers of drugs, genes or other bioactive molecules. In this work, we thoroughly examine the easy-to-obtain, biocompatible, nitrogen-containing carbonaceous quantum dots (N-CQDs) with stable fluorescent properties that are resistant to wide-range pH changes. Moreover, we explain the mechanism of fluorescence quenching at extreme pH conditions. Our in vitro results indicate that N-CQDs penetrate the cell membrane; however, fluorescence intensity measured inside the cells was lower than expected from carbonaceous dots extracellular concentration decrease. We studied the mechanism of quenching and identified reduced form of β-nicotinamide adenine dinucleotide (NADH) as one of the intracellular quenchers. We proved it experimentally that the elucidated redox process triggers the efficient reduction of amide functionalities to non-fluorescent amines on carbonaceous dots surface. We determined the 5 nm–wide reactive redox zone around the N-CQD surface. The better understanding of fluorescence quenching will help to accurately quantify and dose the internalized carbonaceous quantum dots for biomedical applications. Full article

(This article belongs to the Special Issue New Findings in Carbon-Based Materials: From Functionalization to Applications)

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13 pages, 2917 KiB

Open AccessArticle

The Importance of Structural Factors for the Electrochemical Performance of Graphene/Carbon Nanotube/Melamine Powders towards the Catalytic Activity of Oxygen Reduction Reaction

by Piotr Kamedulski, Jerzy P. Lukaszewicz, Lukasz Witczak, Pawel Szroeder and Przemyslaw Ziolkowski

Materials 2021, 14(9), 2448; https://doi.org/10.3390/ma14092448 - 9 May 2021

Cited by 54 | Viewed by 4217

Abstract

In this paper, we show the carbonization of binary composites consisting of graphene nanoplatelets and melamine (GNP/MM), multi-walled carbon nanotubes and melamine (CNT/MM) and trinary composites containing GNP, CNT, and MM. Additionally, the manuscript presents results on the influence of structural factors for [...] Read more.

In this paper, we show the carbonization of binary composites consisting of graphene nanoplatelets and melamine (GNP/MM), multi-walled carbon nanotubes and melamine (CNT/MM) and trinary composites containing GNP, CNT, and MM. Additionally, the manuscript presents results on the influence of structural factors for the electrochemical performance of carbon composites on their catalytic activity. This study contributes to the wide search and design of novel hybrid carbon composites for electrochemical applications. We demonstrate that intensive nitrogen atom insertion is not the governing factor since hybrid system modifications and porous structure sometimes play a more crucial role in the tailoring of electrochemical properties of the carbon hybrids seen as a noble metal-free alternative to traditional electrode materials. Additionally, HRTEM and Raman spectra study allowed for the evaluation of the quality of the obtained hybrid materials. Full article

(This article belongs to the Special Issue New Findings in Carbon-Based Materials: From Functionalization to Applications)

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17 pages, 2792 KiB

Open AccessArticle

Improved Laser Ablation Method for the Production of Luminescent Carbon Particles in Liquids

by Agata Kaczmarek, Piotr Denis, Marcin Krajewski, Tomasz Mościcki, Artur Małolepszy and Jacek Hoffman

Materials 2021, 14(9), 2365; https://doi.org/10.3390/ma14092365 - 1 May 2021

Cited by 6 | Viewed by 2012

Abstract

An improved method for the production of luminescent carbon nanoparticles is proposed in this work. The new method overcomes the disadvantages of commonly used approaches. It involves two-stage laser ablation in water and in aqueous solutions, where the first stage is the laser [...] Read more.

An improved method for the production of luminescent carbon nanoparticles is proposed in this work. The new method overcomes the disadvantages of commonly used approaches. It involves two-stage laser ablation in water and in aqueous solutions, where the first stage is the laser ablation of a graphite target and the second is the shredding of particles produced in the first step. The two-stage method offers the optimization of the laser pulse fluence for the performance of each process. It was found that the two-stage process of laser ablation allows producing photoluminescent carbon structures in pure water. The additional reagent may be added either in the first or second stage. The first stage performed in pure water allows avoiding the contamination of the target. Moreover, it simplifies the identification of the origin of photoluminescence. Two synthesis routes for the preparation of carbon nanoparticles by the proposed method using pure water as well as urea aqueous solution are investigated. It was found that the use of urea as a reagent results in luminescence properties similar to those obtained with other more hazardous amine-based reagents. The influence of the synthesis approach and process parameters on the structural and luminescent properties of nanoparticles is also explored in this work. Full article

(This article belongs to the Special Issue New Findings in Carbon-Based Materials: From Functionalization to Applications)

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14 pages, 4435 KiB

Open AccessArticle

Nitric-Acid Oxidized Single-Walled Carbon Nanohorns as a Potential Material for Bio-Applications—Toxicity and Hemocompatibility Studies

by Wojciech Zieba, Joanna Czarnecka, Tomasz Rusak, Monika Zieba and Artur P. Terzyk

Materials 2021, 14(6), 1419; https://doi.org/10.3390/ma14061419 - 15 Mar 2021

Cited by 8 | Viewed by 2056

Abstract

The results of in vitro studies of single-walled carbon nanohorn (SWCNH) oxidized materials’ cytotoxicity obtained by the cell membrane integrity (Neutral Red Uptake (NRU)) and metabolic activity (by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT)) on A549 and human dermal fibroblasts (HDF) cell lines are presented. We [...] Read more.

The results of in vitro studies of single-walled carbon nanohorn (SWCNH) oxidized materials’ cytotoxicity obtained by the cell membrane integrity (Neutral Red Uptake (NRU)) and metabolic activity (by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT)) on A549 and human dermal fibroblasts (HDF) cell lines are presented. We also present hemocompatibility studies on human and porcine blood, and an erythrocyte concentrate to prove that the obtained samples will not interfere with blood components. Characterization of the materials is supplemented by ζ-potential measurements, Transmission Electron Microscope (TEM) imaging, and thermogravimetric studies (TG). The presented results show the correlation between the specific surface area of materials and the platelet aggregation, when the I_D/I_G ratio determined from Raman spectra correlates with hemoglobin release from the erythrocytes (in whole blood testing). A plausible mechanism explaining the observed correlations is given. The cytotoxicity and hemocompatibility studies prove that the studied materials are acceptable for use in biomedical applications, especially a sample SWCNH-ox-1.5 with the best application potential. Full article

(This article belongs to the Special Issue New Findings in Carbon-Based Materials: From Functionalization to Applications)

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13 pages, 4368 KiB

Open AccessArticle

A New Approach to Obtaining Nano-Sized Graphene Oxide for Biomedical Applications

by Paulina Bolibok, Bartosz Szymczak, Katarzyna Roszek, Artur P. Terzyk and Marek Wiśniewski

Materials 2021, 14(6), 1327; https://doi.org/10.3390/ma14061327 - 10 Mar 2021

Cited by 7 | Viewed by 2268

Abstract

Graphene oxide (GO) is one of the most exciting and widely used materials. A new method of nanographene oxide (n-GO) formation is presented. The described unique sequence of ultrasonication in dimethyl sulfoxide solution allows us to obtain different sizes of n-GO sheets by [...] Read more.

Graphene oxide (GO) is one of the most exciting and widely used materials. A new method of nanographene oxide (n-GO) formation is presented. The described unique sequence of ultrasonication in dimethyl sulfoxide solution allows us to obtain different sizes of n-GO sheets by controlling the timing of the cutting and re-aggregation processes. The obtained n-GO exhibits only minor spectral changes, mainly due to the formation of S-containing surface groups; thus, it can be concluded that the material is not reduced during the process. Maintaining the initial oxygen functionalities together with the required nano-size (down to 200 nm) and high homogeneity are beneficial for extensive applications of n-GO. Moreover, we prove that the obtained material is evidently biocompatible. The calculated half-maximal effective concentration (EC50) increases by 5-fold, i.e., from 50 to 250 µg/mL, when GO is converted to n-GO. As a consequence, the new n-GO neither disturbs blood flow even in the narrowest capillaries nor triggers a toxic influence in surrounding cells. Thus, it can be a serious candidate for drugs and biomolecule carriers administered systemically. Full article

(This article belongs to the Special Issue New Findings in Carbon-Based Materials: From Functionalization to Applications)

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13 pages, 7127 KiB

Open AccessArticle

Luminescent Carbon Dots Synthesized by the Laser Ablation of Graphite in Polyethylenimine and Ethylenediamine

by Agata Kaczmarek, Jacek Hoffman, Jerzy Morgiel, Tomasz Mościcki, Leszek Stobiński, Zygmunt Szymański and Artur Małolepszy

Materials 2021, 14(4), 729; https://doi.org/10.3390/ma14040729 - 4 Feb 2021

Cited by 79 | Viewed by 4426

Abstract

Fluorescent carbon dots (CDs) synthesized by pulsed laser ablation in liquid (PLAL) are still interesting materials due to their possible applications. However, unlike CDs produced by the hydrothermal method, CDs produced the synthesis products by the PLAL method were never separated by dialysis, [...] Read more.

Fluorescent carbon dots (CDs) synthesized by pulsed laser ablation in liquid (PLAL) are still interesting materials due to their possible applications. However, unlike CDs produced by the hydrothermal method, CDs produced the synthesis products by the PLAL method were never separated by dialysis, which differentiates the synthesis products and allows the identification of the main source of fluorescence. In this work, the synthesis of fluorescent carbon dots (CDs) was performed by nanosecond laser ablation of a graphite target immersed in polyethyleneimine (PEI) and ethylenediamine (EDA), and the synthesis products were separated by dialysis. The results of optical measurements showed that the main source of luminescence of the obtained nanostructures are fluorescent particles or quasi-molecular fluorophores created in the ablation process. In the case of ablation in PEI, most of the produced molecular fluorophores are associated with carbogenic nanostructures, while in the case of EDA, free fluorescent molecules dominate. Full article

(This article belongs to the Special Issue New Findings in Carbon-Based Materials: From Functionalization to Applications)

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10 pages, 872 KiB

Open AccessArticle

Joule Heating-Induced Carbon Fibers for Flexible Fiber Supercapacitor Electrodes

by Jin Gu Kang, Gang Wang and Sung-Kon Kim

Materials 2020, 13(22), 5255; https://doi.org/10.3390/ma13225255 - 20 Nov 2020

Cited by 11 | Viewed by 3016

Abstract

Microscale fiber-based supercapacitors have become increasingly important for the needs of flexible, wearable, and lightweight portable electronics. Fiber electrodes without pre-existing cores enable a wider selection of materials and geometries than is possible through core-containing electrodes. The carbonization of fibrous precursors using an [...] Read more.

Microscale fiber-based supercapacitors have become increasingly important for the needs of flexible, wearable, and lightweight portable electronics. Fiber electrodes without pre-existing cores enable a wider selection of materials and geometries than is possible through core-containing electrodes. The carbonization of fibrous precursors using an electrically driven route, different from a conventional high-temperature process, is particularly promising for achieving this structure. Here, we present a facile and low-cost process for producing high-performance microfiber supercapacitor electrodes based on carbonaceous materials without cores. Fibrous carbon nanotubes-agarose composite hydrogels, formed by an extrusion process, are converted to a composite fiber consisting of carbon nanotubes (CNTs) surrounded by an amorphous carbon (aC) matrix via Joule heating. When assembled into symmetrical two-electrode cells, the composite fiber (aC-CNTs) supercapacitor electrodes deliver a volumetric capacitance of 5.1 F cm⁻³ even at a high current density of 118 mA cm⁻³. Based on electrochemical impedance spectroscopy analysis, it is revealed that high electrochemical properties are attributed to fast response kinetics with a characteristic time constant of 2.5 s. The aC-CNTs fiber electrodes exhibit a 94% capacitance retention at 14 mA cm⁻³ for at least 10,000 charge-discharge cycles even when deformed (90° bend), which is essentially the same as that (96%) when not deformed. The aC-CNTs fiber electrodes also demonstrate excellent storage performance under mechanical deformation—for example, 1000 bending-straightening cycles. Full article

(This article belongs to the Special Issue New Findings in Carbon-Based Materials: From Functionalization to Applications)

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16 pages, 5422 KiB

Open AccessArticle

Temperature-Dependent Dynamic Characteristics of Carbon-Fiber-Reinforced Plastic for Different Spectral Loading Patterns

by Chan-Jung Kim

Materials 2020, 13(22), 5238; https://doi.org/10.3390/ma13225238 - 19 Nov 2020

Cited by 9 | Viewed by 1796

Abstract

The dynamic properties of carbon-fiber-reinforced plastic (CFRP) can be efficiently estimated through a modal damping coefficient and a resonance frequency, and the modal parameters can be calculated using a frequency response function (FRF). The modal parameters used in an CFRP FRF are influenced [...] Read more.

The dynamic properties of carbon-fiber-reinforced plastic (CFRP) can be efficiently estimated through a modal damping coefficient and a resonance frequency, and the modal parameters can be calculated using a frequency response function (FRF). The modal parameters used in an CFRP FRF are influenced by the carbon fiber direction, temperature, and spectral loading pattern, as well as the operating conditions. In this study, three parameters—temperature, spectral loading pattern, and carbon fiber direction—were selected as the influential factors for CFRP dynamics, and the sensitivity index formulation was derived from the parameter-dependent FRF of the CFRP structure. The derivatives of the parameter-dependent FRF over the three considered parameters were calculated from the measured modal parameters, and the dynamic sensitivity of the CFRP specimens was explored from the sensitivity index results for five different directional CFRP specimens. The acceleration response of a simple CFRP specimen was obtained via a uniaxial excitation test at temperatures ranging from −8 to 105 °C for the following two spectral loading cases: harmonic and random. Full article

(This article belongs to the Special Issue New Findings in Carbon-Based Materials: From Functionalization to Applications)

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14 pages, 2435 KiB

Open AccessArticle

Highly Effective Methods of Obtaining N-Doped Graphene by Gamma Irradiation

by Piotr Kamedulski, Stanislaw Truszkowski and Jerzy P. Lukaszewicz

Materials 2020, 13(21), 4975; https://doi.org/10.3390/ma13214975 - 5 Nov 2020

Cited by 26 | Viewed by 3037

Abstract

The design and fabrication of a new effective manufacturing method of heteroatom-doped carbon materials is still ongoing. In this paper, we present alternative and facile methods to obtain N-rich graphene with the use of low energy gamma radiation. This method was used as [...] Read more.

The design and fabrication of a new effective manufacturing method of heteroatom-doped carbon materials is still ongoing. In this paper, we present alternative and facile methods to obtain N-rich graphene with the use of low energy gamma radiation. This method was used as a pure and facile method for altering the physical and chemical properties of graphene. The obtained materials have an exceptionally high N content—up to 4 wt %. (dry method) and up to 2 wt %. (wet method). High-resolution transmission electron microscopy (HRTEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman spectra and X-ray photoelectron spectroscopy (XPS) studies allowed us to evaluate the quality of the obtained materials. The presented results will provide new insights in designing and optimizing N-doped carbon materials potentially for the development of anode or cathode materials for electrochemical device applications, especially supercapacitors, metal–air batteries and fuel cells. Nitrogen atoms are exclusively bonded as quaternary groups. The method is expandable to the chemical insertion of other heteroatoms to graphene, especially such as sulfur, boron or phosphorus. Full article

(This article belongs to the Special Issue New Findings in Carbon-Based Materials: From Functionalization to Applications)

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13 pages, 2540 KiB

Open AccessArticle

Nickel-Embedded Carbon Materials Derived from Wheat Flour for Li-Ion Storage

by Wen Ding, Xiaozhong Wu, Yanyan Li, Shuo Wang and Shuping Zhuo

Materials 2020, 13(20), 4611; https://doi.org/10.3390/ma13204611 - 16 Oct 2020

Cited by 8 | Viewed by 2554

Abstract

The biomass-based carbons anode materials have drawn significant attention because of admirable electrochemical performance on account of their nontoxicity and abundance resources. Herein, a novel type of nickel-embedded carbon material (nickel@carbon) is prepared by carbonizing the dough which is synthesized by mixing wheat [...] Read more.

The biomass-based carbons anode materials have drawn significant attention because of admirable electrochemical performance on account of their nontoxicity and abundance resources. Herein, a novel type of nickel-embedded carbon material (nickel@carbon) is prepared by carbonizing the dough which is synthesized by mixing wheat flour and nickel nitrate as anode material in lithium-ion batteries. In the course of the carbonization process, the wheat flour is employed as a carbon precursor, while the nickel nitrate is introduced as both a graphitization catalyst and a pore-forming agent. The in situ formed Ni nanoparticles play a crucial role in catalyzing graphitization and regulating the carbon nanocrystalline structure. Mainly owing to the graphite-like carbon microcrystalline structure and the microporosity structure, the NC-600 sample exhibits a favorable reversible capacity (700.8 mAh g⁻¹ at 0.1 A g⁻¹ after 200 cycles), good rate performance (51.3 mAh g⁻¹ at 20 A g⁻¹), and long-cycling durability (257.25 mAh g⁻¹ at 1 A g⁻¹ after 800 cycles). Hence, this work proposes a promising inexpensive and highly sustainable biomass-based carbon anode material with superior electrochemical properties in LIBs. Full article

(This article belongs to the Special Issue New Findings in Carbon-Based Materials: From Functionalization to Applications)

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18 pages, 6221 KiB

Open AccessArticle

Ciprofloxacin and Graphene Oxide Combination—New Face of a Known Drug

by Karolina Matulewicz, Łukasz Kaźmierski, Marek Wiśniewski, Szymon Roszkowski, Krzysztof Roszkowski, Oliwia Kowalczyk, Archi Roy, Bartosz Tylkowski and Anna Bajek

Materials 2020, 13(19), 4224; https://doi.org/10.3390/ma13194224 - 23 Sep 2020

Cited by 10 | Viewed by 2249

Abstract

Drug modification with nanomaterials is a new trend in pharmaceutical studies and shows promising results, especially considering carbon-based solutions. Graphene and its derivatives have attracted much research interest for their potential applications in biomedical areas as drug modifiers. The following work is a [...] Read more.

Drug modification with nanomaterials is a new trend in pharmaceutical studies and shows promising results, especially considering carbon-based solutions. Graphene and its derivatives have attracted much research interest for their potential applications in biomedical areas as drug modifiers. The following work is a comprehensive study regarding the toxicity of ciprofloxacin (CIP) modified by graphene oxide (GO). The influence on the morphology, viability, cell death pathway and proliferation of T24 and 786-0 cells was studied. The results show that ciprofloxacin modified with graphene oxide (CGO) shows the highest increase in cytotoxic potential, especially in the case of T24 cells. We discovered a clear connection between CIP modification with GO and the increase in its apoptotic potential. Our results show that drug modification with carbon-based nanomaterials might be a promising strategy to improve the qualities of existing drugs. Nevertheless, it is important to remember that cytotoxicity effects are highly dependent on dose and nanomaterial size. It is necessary to conduct further research to determine the optimal dose of GO for drug modification. Full article

(This article belongs to the Special Issue New Findings in Carbon-Based Materials: From Functionalization to Applications)

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13 pages, 3425 KiB

Open AccessArticle

Synthesis of Hybrid Carbon Materials Consisting of N-Doped Microporous Carbon and Amorphous Carbon Nanotubes

by Wojciech Zielinski, Piotr Kamedulski, Aleksander Smolarkiewicz-Wyczachowski, Malgorzata Skorupska, Jerzy P. Lukaszewicz and Anna Ilnicka

Materials 2020, 13(13), 2997; https://doi.org/10.3390/ma13132997 - 6 Jul 2020

Cited by 5 | Viewed by 2317

Abstract

The N-doped hybrid carbon materials containing amorphous carbon nanotubes (ACNTs) were obtained by free growth of a polymer at 200 °C. The improvement of electrical conductivity was achieved by a final carbonization at 600–800 °C under the flow of nitrogen. The microstructure of [...] Read more.

The N-doped hybrid carbon materials containing amorphous carbon nanotubes (ACNTs) were obtained by free growth of a polymer at 200 °C. The improvement of electrical conductivity was achieved by a final carbonization at 600–800 °C under the flow of nitrogen. The microstructure of ACNT/N-doped hybrids was characterized using a transmission electron microscope and X-ray diffusion. Furthermore, their elemental composition was measured using energy-dispersive X-ray spectroscopy and an elemental analyzer. The experimental results indicated that the ACNTs had a diameter in the range of 40–60 nm and the N-doped carbon background contained nitrogen atoms in most bonded pyrrolic-N and quaternary-N groups. The results revealed that the microstructure of the as-grown nanotubes, prepared by the proposed method, is mainly amorphous. This technique introduces the advantages of low cost and process simplicity, which may redeem some drawbacks of the methods commonly used in ACNT synthesis. Full article

(This article belongs to the Special Issue New Findings in Carbon-Based Materials: From Functionalization to Applications)

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14 pages, 4697 KiB

Open AccessArticle

Improving the Performance of Zn-Air Batteries with N-Doped Electroexfoliated Graphene

by Anna Ilnicka, Malgorzata Skorupska, Piotr Romanowski, Piotr Kamedulski and Jerzy P. Lukaszewicz

Materials 2020, 13(9), 2115; https://doi.org/10.3390/ma13092115 - 2 May 2020

Cited by 14 | Viewed by 2898

Abstract

The constantly growing demand for active, durable, and low-cost electrocatalysts usable in energy storage devices, such as supercapacitors or electrodes in metal-air batteries, has triggered the rapid development of heteroatom-doped carbon materials, which would, among other things, exhibit high catalytic activity in the [...] Read more.

The constantly growing demand for active, durable, and low-cost electrocatalysts usable in energy storage devices, such as supercapacitors or electrodes in metal-air batteries, has triggered the rapid development of heteroatom-doped carbon materials, which would, among other things, exhibit high catalytic activity in the oxygen reduction reaction (ORR). In this article, a method of synthesizing nitrogen-doped graphene is proposed. Few-layered graphene sheets (FL-graphene) were prepared by electrochemical exfoliation of commercial graphite in a Na₂SO₄ electrolyte with added calcium carbonate as a separator of newly-exfoliated FL-graphene sheets. Exfoliated FL-graphene was impregnated with a suspension of green algae used as a nitrogen carrier. Impregnated FL-graphene was carbonized at a high temperature under the flow of nitrogen. The N-doped FL-graphene was characterized through instrumental methods: high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, and Raman spectroscopy. Electrochemical performance was determined using cyclic voltamperometry and linear sweep voltamperometry to check catalytic activity in ORR. The N-doped electroexfoliated FL-graphene obeyed the four-electron transfer pathways, leading us to further test these materials as electrode components in rechargeable zinc-air batteries. The obtained results for Zn-air batteries are very important for future development of industry, because the proposed graphene electrode materials do not contain any heavy and noble metals in their composition. Full article

(This article belongs to the Special Issue New Findings in Carbon-Based Materials: From Functionalization to Applications)

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13 pages, 4261 KiB

Open AccessArticle

Cytotoxic or Not? Disclosing the Toxic Nature of Carbonaceous Nanomaterials through Nano–Bio Interactions

by Joanna Czarnecka, Marek Wiśniewski, Natalia Forbot, Paulina Bolibok, Artur P. Terzyk and Katarzyna Roszek

Materials 2020, 13(9), 2060; https://doi.org/10.3390/ma13092060 - 29 Apr 2020

Cited by 22 | Viewed by 2453

Abstract

The cytotoxic influence of two different carbonaceous nanomaterials on human mesenchymal stem cells (MSCs) cultured in vitro was compared in the short (1–3 days) and long term (up to 60 days). Amorphous carbon and single-walled carbon nanotubes were chosen and evaluated due to [...] Read more.

The cytotoxic influence of two different carbonaceous nanomaterials on human mesenchymal stem cells (MSCs) cultured in vitro was compared in the short (1–3 days) and long term (up to 60 days). Amorphous carbon and single-walled carbon nanotubes were chosen and evaluated due to their contrasting physicochemical properties. Both materials, though supposed similarly low-toxic in basic short-term cytotoxicity assays, demonstrated dramatically different properties in the long-term study. The surface chemistry and biomolecule-adsorption capacity turned out to be crucial factors influencing cytotoxicity. We proved that amorphous carbon is able to weakly bind a low-affinity protein coat (so-called soft corona), while carbon nanotubes behaved oppositely. Obtained results from zeta-potential and adsorption measurements for both nanomaterials confirmed that a hard protein corona was present on the single-walled carbon-nanotube surface that aggravated their cytotoxic influence. The long-term exposure of the mesenchymal stem cells to carbon nanotubes, coated by the strongly bound proteins, showed a significant decrease in cell-growth rate, followed by cell senescence and death. These results are of great importance in the light of increasing nanomaterial applications in biomedicine and cell-based therapies. Our better understanding of the puzzling cytotoxicity of carbonaceous nanomaterials, reflecting their surface chemistry and interactions, is helpful in adjusting their properties when tailored for specific applications. Full article

(This article belongs to the Special Issue New Findings in Carbon-Based Materials: From Functionalization to Applications)

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23 pages, 1075 KiB

Open AccessReview

Carbon Materials in Electroanalysis of Preservatives: A Review

by Slawomir Michalkiewicz, Agata Skorupa and Magdalena Jakubczyk

Materials 2021, 14(24), 7630; https://doi.org/10.3390/ma14247630 - 11 Dec 2021

Cited by 33 | Viewed by 3321

Abstract

Electrochemical sensors in electroanalysis are a particularly useful and relatively simple way to identify electroactive substances. Among the materials used to design sensors, there is a growing interest in different types of carbon. This is mainly due to its non-toxic properties, low cost, [...] Read more.

Electrochemical sensors in electroanalysis are a particularly useful and relatively simple way to identify electroactive substances. Among the materials used to design sensors, there is a growing interest in different types of carbon. This is mainly due to its non-toxic properties, low cost, good electrical conductivity, wide potential range, and the possibility of using it in both aqueous and nonaqueous media. The electrodes made of carbon, and especially of carbon modified with different materials, are currently most often used in the voltammetric analysis of various compounds, including preservatives. The objective of this paper is to present the characteristics and suitability of different carbon materials for the construction of working electrodes used in the voltammetric analysis. Various carbon materials were considered and briefly discussed. Their analytical application was presented on the example of the preservatives commonly used in food, cosmetic, and pharmaceutical preparations. It was shown that for the electroanalysis of preservatives, mainly carbon electrodes modified with various modifiers are used. These modifications ensure appropriate selectivity, high sensitivity, low limits of detection and quantification, as well as a wide linearity range of voltammetric methods of their identification and determination. Full article

(This article belongs to the Special Issue New Findings in Carbon-Based Materials: From Functionalization to Applications)

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