Next Issue
Previous Issue

Table of Contents

C, Volume 5, Issue 2 (June 2019)

  • Issues are regarded as officially published after their release is announced to the table of contents alert mailing list.
  • You may sign up for e-mail alerts to receive table of contents of newly released issues.
  • PDF is the official format for papers published in both, html and pdf forms. To view the papers in pdf format, click on the "PDF Full-text" link, and use the free Adobe Readerexternal link to open them.
View options order results:
result details:
Displaying articles 1-21
Export citation of selected articles as:
Open AccessArticle
Mechanical Behavior of Porous Functionally Graded Nanocomposite Materials
Received: 5 May 2019 / Revised: 3 June 2019 / Accepted: 13 June 2019 / Published: 22 June 2019
Viewed by 416 | PDF Full-text (4008 KB) | HTML Full-text | XML Full-text
Abstract
Materials used in biomedical applications need to cope with a wide set of requisites, one of them being their structural adequacy to a specific application. Thus, it is important to understand their behavior under specified standard cases, namely concerning their structural performance. This [...] Read more.
Materials used in biomedical applications need to cope with a wide set of requisites, one of them being their structural adequacy to a specific application. Thus, it is important to understand their behavior under specified standard cases, namely concerning their structural performance. This objective constituted the focus of the present study, where nanocomposite functionally graded materials integrating different porosity distributions were analyzed. To this purpose a set of numerical simulations based on the finite element method, reproducing American Society for Testing and Materials (ASTM) tensile and bending tests were considered. The results obtained show a good performance of the models implemented through their preliminary verification. It is also possible to conclude that carbon nanotubes and porosity distributions provide different and opposite effects in the context of the nanocomposite materials analyzed. Full article
Figures

Figure 1

Open AccessReview
Carbon Dots for Sensing and Killing Microorganisms
Received: 12 April 2019 / Revised: 23 May 2019 / Accepted: 29 May 2019 / Published: 14 June 2019
Cited by 1 | Viewed by 529 | PDF Full-text (5066 KB) | HTML Full-text | XML Full-text
Abstract
Carbon dots (or carbon quantum dots) are small (less than 10 nm) and luminescent carbon nanoparticles with some form of surface passivation. As an emerging class of nanomaterials, carbon dots have found wide applications in medicine, bioimaging, sensing, electronic devices, and catalysis. In [...] Read more.
Carbon dots (or carbon quantum dots) are small (less than 10 nm) and luminescent carbon nanoparticles with some form of surface passivation. As an emerging class of nanomaterials, carbon dots have found wide applications in medicine, bioimaging, sensing, electronic devices, and catalysis. In this review, we focus on the recent advancements of carbon dots for sensing and killing microorganisms, including bacteria, fungi, and viruses. Synthesis, functionalization, and a toxicity profile of these carbon dots are presented. We also discuss the underlying mechanisms of carbon dot-based sensing and killing of microorganisms. Full article
(This article belongs to the Special Issue Recent Advances in Carbon Dots)
Figures

Graphical abstract

Open AccessArticle
Chemical Recycling of Consumer-Grade Black Plastic into Electrically Conductive Carbon Nanotubes
Received: 15 March 2019 / Revised: 13 May 2019 / Accepted: 14 May 2019 / Published: 12 June 2019
Viewed by 1701 | PDF Full-text (1265 KB) | HTML Full-text | XML Full-text
Abstract
The global plastics crisis has recently focused scientists’ attention on finding technical solutions for the ever-increasing oversupply of plastic waste. Black plastic is one of the greatest contributors to landfill waste, because it cannot be sorted using industrial practices based on optical reflection. [...] Read more.
The global plastics crisis has recently focused scientists’ attention on finding technical solutions for the ever-increasing oversupply of plastic waste. Black plastic is one of the greatest contributors to landfill waste, because it cannot be sorted using industrial practices based on optical reflection. However, it can be readily upcycled into carbon nanotubes (CNTs) using a novel liquid injection reactor (LIR) chemical vapor deposition (CVD) method. In this work, CNTs were formed using black and white polystyrene plastics to demonstrate that off-the-shelf materials can be used as feedstock for growth of CNTs. Scanning electron microscopy analysis suggests the CNTs from plastic sources improve diameter distribution homogeneity, with slightly increased diameters compared with control samples. Slight improvements in quality, as determined by Raman spectroscopy of the D and G peaks, suggest that plastics could lead to increased quality of CNTs. A small device was constructed as a demonstrator model to increase impact and public engagement. Full article
(This article belongs to the Special Issue Carbon in the Circular Economy)
Figures

Figure 1

Open AccessArticle
Microbiological Properties of Microwave-Activated Carbons Impregnated with Enoxil and Nanoparticles of Ag and Se
Received: 29 April 2019 / Revised: 26 May 2019 / Accepted: 3 June 2019 / Published: 8 June 2019
Viewed by 511 | PDF Full-text (4185 KB) | HTML Full-text | XML Full-text
Abstract
Microwave-activated carbons from walnut shells (ACMW) were impregnated with Ag and Se nanoparticles and with the Enoxil biologically active preparation, and the microbiological properties of the obtained composites were studied. To increase the functionality of the adsorbent, the activated carbon was oxidized with [...] Read more.
Microwave-activated carbons from walnut shells (ACMW) were impregnated with Ag and Se nanoparticles and with the Enoxil biologically active preparation, and the microbiological properties of the obtained composites were studied. To increase the functionality of the adsorbent, the activated carbon was oxidized with ozone, resulting in ACMWO containing aliphatic and aromatic carboxylic groups. There was a considerable decrease in the specific surface of the activated carbon after the oxidation process. Nitrogen adsorption was used to determine the structural parameters of the activated carbons. A simultaneous thermal analysis was used to study the thermal behavior of intact and oxidized activated carbons. Infrared spectroscopy was applied to analyze the surface chemistry of the adsorbents. The microbiological activity of the activated carbons was studied using Escherichia coli bacteria and Candida albicans fungi. The kinetic study of the microbiological activity allowed the estimation of the bactericidal/fungicidal action time of the activated carbons. Full article
(This article belongs to the Special Issue Biomedical Applications of Carbon Materials)
Figures

Graphical abstract

Open AccessArticle
Mechanothermal Approach for N-, S-, P-, and B-Doping of Carbon Nanotubes: Methodology and Catalytic Performance in Wet Air Oxidation
Received: 12 April 2019 / Revised: 17 May 2019 / Accepted: 29 May 2019 / Published: 4 June 2019
Viewed by 518 | PDF Full-text (2544 KB) | HTML Full-text | XML Full-text
Abstract
The texture and the surface chemistry of carbon nanotubes (CNTs) were modified using a solvent-free methodology involving a ball-milling mechanical treatment and thermal treatment under nitrogen in the presence of adequate precursors (melamine, sodium thiosulfate, sodium dihydrogen phosphate, and boric acid) of different [...] Read more.
The texture and the surface chemistry of carbon nanotubes (CNTs) were modified using a solvent-free methodology involving a ball-milling mechanical treatment and thermal treatment under nitrogen in the presence of adequate precursors (melamine, sodium thiosulfate, sodium dihydrogen phosphate, and boric acid) of different heteroatoms (N, S, P, and B, respectively). The incorporation of these heteroatoms promotes significant changes in the pristine textural and chemical properties. This easy post-doping method allows the introduction of large concentrations of heteroatoms. Their effect on the catalytic activity of the materials was evaluated in the oxidation of oxalic acid by catalytic wet air oxidation (CWAO), as an alternative to the noble metal and rare earth oxide catalysts traditionally used in this process. Improved catalytic activities were obtained using the N-, P-, and B-doped CNTs in oxalic acid oxidation, while the S-doped CNT sample underperformed in comparison to the pristine material. Full article
(This article belongs to the Special Issue Nitrogen-Doped Carbon Materials)
Figures

Graphical abstract

Open AccessReview
The Advances in Biomedical Applications of Carbon Nanotubes
Received: 16 April 2019 / Revised: 16 May 2019 / Accepted: 17 May 2019 / Published: 23 May 2019
Viewed by 566 | PDF Full-text (766 KB) | HTML Full-text | XML Full-text
Abstract
Unique chemical, physical, and biological features of carbon nanotubes make them an ideal candidate for myriad applications in industry and biomedicine. Carbon nanotubes have excellent electrical and thermal conductivity, high biocompatibility, flexibility, resistance to corrosion, nano-size, and a high surface area, which can [...] Read more.
Unique chemical, physical, and biological features of carbon nanotubes make them an ideal candidate for myriad applications in industry and biomedicine. Carbon nanotubes have excellent electrical and thermal conductivity, high biocompatibility, flexibility, resistance to corrosion, nano-size, and a high surface area, which can be tailored and functionalized on demand. This review discusses the progress and main fields of bio-medical applications of carbon nanotubes based on recently-published reports. It encompasses the synthesis of carbon nanotubes and their application for bio-sensing, cancer treatment, hyperthermia induction, antibacterial therapy, and tissue engineering. Other areas of carbon nanotube applications were out of the scope of this review. Special attention has been paid to the problem of the toxicity of carbon nanotubes. Full article
(This article belongs to the Special Issue Biomedical Applications of Carbon Materials)
Figures

Graphical abstract

Open AccessArticle
Preparation of Few-Layer Graphene/Carbon Nanotube Hybrids Using Oxide Spinel Catalysts
Received: 18 April 2019 / Revised: 13 May 2019 / Accepted: 14 May 2019 / Published: 21 May 2019
Viewed by 547 | PDF Full-text (2292 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Functional 3D materials can be developed from graphene-based hybrids by introducing other nanomaterials, with multi-walled carbon nanotubes (CNTs) being the most studied additive. For large-scale applications, few-layer graphene (FLG)-CNT hybrids are produced by catalytic chemical vapor deposition (c-CVD) starting from a mixture of [...] Read more.
Functional 3D materials can be developed from graphene-based hybrids by introducing other nanomaterials, with multi-walled carbon nanotubes (CNTs) being the most studied additive. For large-scale applications, few-layer graphene (FLG)-CNT hybrids are produced by catalytic chemical vapor deposition (c-CVD) starting from a mixture of catalysts (one for FLG and one for CNTs) in the required proportions. Due to the difference in growth kinetics between CNTs and FLG, the composition of such hybrids is not well controlled. In this study, we report the single-step preparation of FLG-CNT hybrid materials by a fixed-bed c-CVD process using a single catalyst with the formula AlxCo1−xFe2O4 (x = 0.025–0.10). Different catalysts (with varying x) were prepared by the citrate–nitrate gel combustion method. Then, c-CVD synthesis was carried out at 650 °C in a horizontal fixed-bed reactor using ethylene as the carbon source. Only FLG was obtained when using CoFe2O4. However, the introduction of small amounts of Al (x < 0.05) induced the simultaneous production of CNTs, leading to the formation of uniform FLG-CNT hybrids. For catalysts with higher Al content (e.g., AlCoFeO4), CNTs were selectively produced. Thus, we observed the existence of a narrow Al-doping window, where CNTs and FLG can be obtained simultaneously. Our results can pave the way to developing high-yield single catalyst-based CVD synthesis of FLG-CNT hybrid materials. Full article
Figures

Graphical abstract

Open AccessReview
Methods for the Treatment of Cattle Manure—A Review
Received: 28 February 2019 / Revised: 29 April 2019 / Accepted: 6 May 2019 / Published: 15 May 2019
Viewed by 462 | PDF Full-text (858 KB) | HTML Full-text | XML Full-text
Abstract
Environmental concerns, caused by greenhouse gases released to the atmosphere and overrunning of nutrients and pathogens to water bodies, have led to reducing direct spread onto the land of cattle manure. In addition, this practice can be a source of water and air [...] Read more.
Environmental concerns, caused by greenhouse gases released to the atmosphere and overrunning of nutrients and pathogens to water bodies, have led to reducing direct spread onto the land of cattle manure. In addition, this practice can be a source of water and air pollution and toxicity to life by the release of undesirable heavy metals. Looking at the current practices, it is evident that most farms separate solids for recycling purposes, store slurries in large lagoons or use anaerobic digestion to produce biogas. The review explores the potential for cattle manure as an energy source due to its relatively large calorific value (HHV of 8.7–18.7 MJ/kg dry basis). This property is beneficial for thermochemical conversion processes, such as gasification and pyrolysis. This study also reviews the potential for upgrading biogas for transportation and heating use. This review discusses current cattle manure management technologies—biological treatment and thermochemical conversion processes—and the diverse physical and chemical properties due to the differences in farm practices. Full article
(This article belongs to the Special Issue Advanced Coal, Biomass and Waste Conversion Technologies)
Figures

Graphical abstract

Open AccessArticle
Highly Active, High Specific Surface Area Fe/C/N ORR Electrocatalyst from Liquid Precursors by Combination of CO2 Laser Pyrolysis and Single NH3 Thermal Post-Treatment
Received: 19 March 2019 / Revised: 24 April 2019 / Accepted: 30 April 2019 / Published: 14 May 2019
Viewed by 832 | PDF Full-text (3032 KB) | HTML Full-text | XML Full-text
Abstract
This paper reports original results on the synthesis and characterization of Fe/C/N ORR electrocatalysts obtained by a combination of CO2 laser pyrolysis and thermal post-treatment. The precursor liquid media, consisting in a 14 g·L−1 iron III acetylacetonate solution in toluene, was [...] Read more.
This paper reports original results on the synthesis and characterization of Fe/C/N ORR electrocatalysts obtained by a combination of CO2 laser pyrolysis and thermal post-treatment. The precursor liquid media, consisting in a 14 g·L−1 iron III acetylacetonate solution in toluene, was aerosolized and then exposed to a CO2 laser beam for pyrolysis in continuous flow. Ammonia was used in the pyrolysis process, both as the laser wavelength absorbing gas (i.e., energy transfer agent) and as the sole source of nitrogen. After the laser pyrolysis step, the material was submitted to thermal post-treatment under argon on the one hand, and ammonia on another hand. The three materials—one as-prepared, one thermally treated under argon, and one thermally treated under ammonia—were characterized, in particular, through specific surface area determination, XPS analysis, and ORR measurement. It was found that both kinds of thermal treatment significantly improved the ORR performances, which were evaluated on porous electrodes. Indeed, while the as-prepared material showed an ORR onset potential at ≈790 mV vs. the standard hydrogen electrode (SHE) in HClO4 1M, the argon treatment increased the latter to ≈820 mV, and the ammonia treatment led to a very high value of ≈910 mV. Selectivities of 3.65 and 3.93 were measured for the argon and ammonia treated materials, respectively. The outstanding ORR performance resulting from the ammonia treatment is probably related to the very high BET specific surface area measured at 1130 m2·g−1, which was notably obtained without using any templating or sacrificial component in the precursor media. Full article
(This article belongs to the Special Issue Nitrogen-Doped Carbon Materials)
Figures

Graphical abstract

Open AccessArticle
Fabrication of Graphene-Reinforced Nanocomposites with Improved Fracture Toughness in Net Shape for Complex 3D Structures via Digital Light Processing
Received: 21 March 2019 / Revised: 28 April 2019 / Accepted: 30 April 2019 / Published: 9 May 2019
Viewed by 557 | PDF Full-text (3467 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
A solvent-free method to fabricate graphene-reinforced nanocomposites in net shape via digital light processing (DLP) 3D printing has been developed in this work. The effect of graphene nanofillers on resin viscosity and wettability for various printing parameters has been examined, with a systematic [...] Read more.
A solvent-free method to fabricate graphene-reinforced nanocomposites in net shape via digital light processing (DLP) 3D printing has been developed in this work. The effect of graphene nanofillers on resin viscosity and wettability for various printing parameters has been examined, with a systematic characterization of the mechanical and thermomechanical properties. With the addition of 0.5 wt.% graphene nanoplatelets in the resin, the flexural modulus and fracture toughness have been improved by 14% and 28% from neat resin, respectively. Thermomechanical properties of graphene-reinforced nanocomposites were also enhanced compared with the neat resin, without scarification in their printability. The feasibility of utilizing the DLP method to fabricate a fracture toughness specimen (KIC test) without complex skill-dependent notch preparation steps was explored, with different notch tip angles printed for net-shaped specimens. This provided a simple and versatile way to perform a quick examination of reinforcing efficiency from nanofillers at very low cost with high resolution and reproducibility. To demonstrate the suitability of current resins for complexly shaped structures, a gyroid scaffold for tissue engineering applications based on current graphene nanocomposite resins has been successfully fabricated via DLP, showing the great potential of current photocurable resins for applications in various fields such as tissue engineering or personalized medical devices without the cost barriers of traditional methods. Full article
(This article belongs to the Special Issue Graphene-Reinforced Polymer Nanocomposites)
Figures

Figure 1

Open AccessReview
Recent Advancements in Doped/Co-Doped Carbon Quantum Dots for Multi-Potential Applications
Received: 31 March 2019 / Revised: 26 April 2019 / Accepted: 28 April 2019 / Published: 6 May 2019
Cited by 1 | Viewed by 658 | PDF Full-text (5213 KB) | HTML Full-text | XML Full-text
Abstract
Carbon quantum dots (CQDs)/carbon nanodots are a new class of fluorescent carbon nanomaterials having an approximate size in the range of 2–10 nm. The majority of the reported review articles have discussed about the development of the CQDs (via simple and cost-effective synthesis [...] Read more.
Carbon quantum dots (CQDs)/carbon nanodots are a new class of fluorescent carbon nanomaterials having an approximate size in the range of 2–10 nm. The majority of the reported review articles have discussed about the development of the CQDs (via simple and cost-effective synthesis methods) for use in bio-imaging and chemical-/biological-sensing applications. However, there is a severe lack of consolidated studies on the recently developed CQDs (especially doped/co-doped) that are utilized in different areas of application. Hence, in this review, we have extensively discussed about the recent development in doped and co-doped CQDs (using elements/heteroatoms—e.g., boron (B), fluorine (F), nitrogen (N), sulphur (S), and phosphorous (P)), along with their synthesis method, reaction conditions, and/or quantum yield (QY), and their emerging multi-potential applications including electrical/electronics (such as light emitting diode (LED) and solar cells), fluorescent ink for anti-counterfeiting, optical sensors (for detection of metal ions, drugs, and pesticides/fungicides), gene delivery, and temperature probing. Full article
(This article belongs to the Special Issue Recent Advances in Carbon Dots)
Figures

Graphical abstract

Open AccessArticle
Vertically Aligned Few-Layered Graphene-Based Non-Cryogenic Bolometer
Received: 5 April 2019 / Revised: 25 April 2019 / Accepted: 26 April 2019 / Published: 2 May 2019
Viewed by 498 | PDF Full-text (2191 KB) | HTML Full-text | XML Full-text
Abstract
In this study, we report the photoresponse of vertically aligned few-layered graphene (VAG) upon infra-red (IR) irradiation at room temperature. Four probe measurements showed the current–voltage (I–V) characteristic of electrical switching during pulsed IR irradiation. The photoresponse reported here for VAG was significantly [...] Read more.
In this study, we report the photoresponse of vertically aligned few-layered graphene (VAG) upon infra-red (IR) irradiation at room temperature. Four probe measurements showed the current–voltage (I–V) characteristic of electrical switching during pulsed IR irradiation. The photoresponse reported here for VAG was significantly higher than that reported for carbon nanotube (CNT) samples. Our investigation shows that such a photoresponse arose solely from the bolometric effect, where the conductivity changed with temperature. The resistance magnitude of the VAGs increased ~two fold for each 6 °C increase in temperature. Also, the Thermal Coefficient of Resistance (TCR) in this region was ~11%/K, which is the highest TCR value reported for any carbon nanomaterial. Full article
(This article belongs to the Special Issue Carbon Nanomaterials for Energy Conversion and Storage Technologies)
Figures

Graphical abstract

Open AccessArticle
Sustainable Recycling of Formic Acid by Bio-Catalytic CO2 Capture and Re-Hydrogenation
Received: 22 March 2019 / Revised: 20 April 2019 / Accepted: 22 April 2019 / Published: 1 May 2019
Viewed by 513 | PDF Full-text (1710 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Formic acid (FA) is a promising reservoir for hydrogen storage and distribution. Its dehydrogenation releases CO2 as a by-product, which limits its practical application. A proof of concept for a bio-catalytic system that simultaneously combines the dehydrogenation of formic acid for H [...] Read more.
Formic acid (FA) is a promising reservoir for hydrogen storage and distribution. Its dehydrogenation releases CO2 as a by-product, which limits its practical application. A proof of concept for a bio-catalytic system that simultaneously combines the dehydrogenation of formic acid for H2, in-situ capture of CO2 and its re-hydrogenation to reform formic acid is demonstrated. Enzymatic reactions catalyzed by carbonic anhydrase (CA) and formate dehydrogenase (FDH) under ambient condition are applied for in-situ CO2 capture and re-hydrogenation, respectively, to develop a sustainable system. Continuous production of FA from stripped CO2 was achieved at a rate of 40% using FDH combined with sustainable co-factor regeneration achieved by electrochemistry. In this study, the complete cycle of FA dehydrogenation, CO2 capture, and re-hydrogenation of CO2 to FA has been demonstrated in a single system. The proposed bio-catalytic system has the potential to reduce emissions of CO2 during H2 production from FA by effectively using it to recycle FA for continuous energy supply. Full article
(This article belongs to the Special Issue Advanced Coal, Biomass and Waste Conversion Technologies)
Figures

Graphical abstract

Open AccessArticle
Finger-Like Carbon-Based Nanostructures Produced by Combustion of Flour-Based Sticks (Spaghetti)
Received: 1 March 2019 / Revised: 29 March 2019 / Accepted: 16 April 2019 / Published: 29 April 2019
Viewed by 404 | PDF Full-text (7527 KB) | HTML Full-text | XML Full-text
Abstract
Biomass is becoming particularly important as a starting material for advanced carbon structures. In this study, we found interesting nanostructures on the surface of burnt spaghetti using scanning electron microscopy, transmission electron microscopy (TEM), and energy dispersive X-ray spectroscopy (EDX) for analysis. The [...] Read more.
Biomass is becoming particularly important as a starting material for advanced carbon structures. In this study, we found interesting nanostructures on the surface of burnt spaghetti using scanning electron microscopy, transmission electron microscopy (TEM), and energy dispersive X-ray spectroscopy (EDX) for analysis. The structures were elongated and finger-like, with evidence that the tubes have shell and core components. The shell was carbon that included amorphous and layered graphene structures. EDX showed enriched potassium and phosphorous in the core and at the tip of the tubes. The results indicate that tube formation depends on phase separation of polar/ionic and nonpolar moieties when water is produced in the biomass from the pyrolysis/combustion. The tube growth is most probably due to the raising pressure of vapor that cannot escape through the carbon film that is formed at the surface of the stick from flame heat. This process resembles glass blowing or volcanic activity, where the carbon acts as the glass or earth’s crust, respectively. These observations suggest that new interesting tubular nanostructures with different properties on the inside and outside can be produced in a relatively simple way, utilizing processes of combustion of starch-rich biomass materials. Full article
(This article belongs to the Special Issue Advanced Coal, Biomass and Waste Conversion Technologies)
Figures

Graphical abstract

Open AccessCommunication
Temperature-Dependence of Solvent-Induced Stokes Shift and Fluorescence Tunability in Carbon Nanodots
Received: 29 March 2019 / Revised: 12 April 2019 / Accepted: 16 April 2019 / Published: 24 April 2019
Cited by 1 | Viewed by 496 | PDF Full-text (1293 KB) | HTML Full-text | XML Full-text
Abstract
We carried out a cryogenic investigation on the optical properties of carbon dots, aiming to better understand their emission mechanism and the role of the solvent. The solvatochromic Stokes shift is quantified by a low temperature approach which allows freezing of the photo-excited [...] Read more.
We carried out a cryogenic investigation on the optical properties of carbon dots, aiming to better understand their emission mechanism and the role of the solvent. The solvatochromic Stokes shift is quantified by a low temperature approach which allows freezing of the photo-excited state of carbon dots, preventing any solvation relaxation. Moreover, the reduction in temperature helps to identify the dynamical inhomogeneous contribution to the broadening of the emission band; therefore, disentangling the role of solvent from other types of broadening, such as the homogeneous and the static inhomogeneous contributions. Full article
(This article belongs to the Special Issue Recent Advances in Carbon Dots)
Figures

Graphical abstract

Open AccessReview
Bioimaging Applications of Carbon Nanodots: A Review
Received: 31 March 2019 / Revised: 12 April 2019 / Accepted: 16 April 2019 / Published: 22 April 2019
Cited by 1 | Viewed by 572 | PDF Full-text (12665 KB) | HTML Full-text | XML Full-text
Abstract
Carbon nanodots (CNDs) is the newest member of carbon-based nanomaterials and one of the most promising for the development of new, advanced applications. Owing to their unique and unparalleled physicochemical and photoluminescent properties, they are considered to be a rising star among nanomaterials. [...] Read more.
Carbon nanodots (CNDs) is the newest member of carbon-based nanomaterials and one of the most promising for the development of new, advanced applications. Owing to their unique and unparalleled physicochemical and photoluminescent properties, they are considered to be a rising star among nanomaterials. During the last decade, many applications have been developed based on CNDs. Among others, they have been used as bioimaging agents to label cells and tissues. In this review, we will discuss the advancements in the applications of CNDs in in the field of imaging, in all types of organisms (i.e., prokaryotes, eukaryotes, and animals). Selective imaging of one type of cells over another, imaging of (bio)molecules inside cells and tumor-targeting imaging are some of the studies that will be discussed hereafter. We hope that this review will assist researchers with obtaining a holistic view of the developed applications and hit on new ideas so that more advanced applications can be developed in the near future. Full article
(This article belongs to the Special Issue Recent Advances in Carbon Dots)
Figures

Graphical abstract

Open AccessArticle
Electrochemical Properties of Graphene Oxide Nanoribbons/Polypyrrole Nanocomposites
Received: 5 February 2019 / Revised: 1 April 2019 / Accepted: 8 April 2019 / Published: 12 April 2019
Viewed by 496 | PDF Full-text (7243 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Graphene is a highly studied material due to its unique electrical, optical, and mechanical properties. Graphene is widely applied in the field of energy such as in batteries, supercapacitors, and solar cells. The properties of graphene can be further improved by making nanocomposites [...] Read more.
Graphene is a highly studied material due to its unique electrical, optical, and mechanical properties. Graphene is widely applied in the field of energy such as in batteries, supercapacitors, and solar cells. The properties of graphene can be further improved by making nanocomposites with conducting polymers. In this work, graphene oxide nanoribbons (GONRs) were synthesized by unzipping multiwall carbon nanotubes. Graphene nanoribbons were used to make nanocomposites with polypyrrole for energy storage applications. The synthesized nanocomposites were structurally and electrochemically characterized to understand their structure and electrochemical properties. The electrochemical characterizations of these nanocomposites were carried out using cyclic voltammetry. The specific capacitance of the nanocomposites was observed to decrease with increasing scan rates. The highest specific capacitance of 2066 F/g was observed using cyclic voltammetry for the optimized nanocomposite of GONR and polypyrrole. Our study suggests that the electrochemical properties of graphene or polypyrrole can be improved by making their composites and that they could be successfully used as electrode materials for energy storage applications. This study can also be extended to the self-assembly of other conducting polymers and graphene nanoribbons through a simple route for various other applications. Full article
(This article belongs to the Special Issue Carbon Nanomaterials for Energy Conversion and Storage Technologies)
Figures

Graphical abstract

Open AccessFeature PaperArticle
A Multifunctional Wearable Device with a Graphene/Silver Nanowire Nanocomposite for Highly Sensitive Strain Sensing and Drug Delivery
Received: 9 March 2019 / Revised: 25 March 2019 / Accepted: 28 March 2019 / Published: 4 April 2019
Cited by 1 | Viewed by 906 | PDF Full-text (4598 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Advances in wearable, highly sensitive and multifunctional strain sensors open up new opportunities for the development of wearable human interface devices for various applications such as health monitoring, smart robotics and wearable therapy. Herein, we present a simple and cost-effective method to fabricate [...] Read more.
Advances in wearable, highly sensitive and multifunctional strain sensors open up new opportunities for the development of wearable human interface devices for various applications such as health monitoring, smart robotics and wearable therapy. Herein, we present a simple and cost-effective method to fabricate a multifunctional strain sensor consisting of a skin-mountable dry adhesive substrate, a robust sensing component and a transdermal drug delivery system. The sensor has high piezoresisitivity to monitor real-time signals from finger bending to ulnar pulse. A transdermal drug delivery system consisting of polylactic-co-glycolic acid nanoparticles and a chitosan matrix is integrated into the sensor and is able to release the nanoparticles into the stratum corneum at a depth of ~60 µm. Our approach to the design of multifunctional strain sensors will lead to the development of cost-effective and well-integrated multifunctional wearable devices. Full article
(This article belongs to the Special Issue Biomedical Applications of Carbon Materials)
Figures

Graphical abstract

Open AccessArticle
Plasma-Derived Graphene-Based Materials for Water Purification and Energy Storage
Received: 2 March 2019 / Revised: 22 March 2019 / Accepted: 28 March 2019 / Published: 3 April 2019
Viewed by 595 | PDF Full-text (6371 KB) | HTML Full-text | XML Full-text
Abstract
Several crucial problems, such as rapid population growth and extended demands for food, water and fuels, could lead to a severe lack of clean water and an energy crisis in the coming decade. Therefore, low-cost and highly-efficient technologies related to filtration of alternative [...] Read more.
Several crucial problems, such as rapid population growth and extended demands for food, water and fuels, could lead to a severe lack of clean water and an energy crisis in the coming decade. Therefore, low-cost and highly-efficient technologies related to filtration of alternative water supplies (e.g., purification of wastewater and water-rich liquids) and advanced energy storage (e.g., supercapacitors) could play a crucial role to overcome such challenges. A promising class of solid materials for these purposes is exfoliated graphene, and more specifically, its nanoporous forms that exhibit large specific surface areas and pore volumes. In the current work, two plasma-exfoliated graphene-based materials with distinctive morphological and porosity features, including non-porous and low-specific surface area platelets versus nanoporous and high-specific surface area flakes, were tested as filters for water purification purposes (i.e., decolourization and deacidification) and as electrodes for supercapacitors (i.e., ion electrosorption). The findings of this study suggest that a nanoporous and large specific surface area graphene-based material promotes the water purification behaviour by removing contaminants from water-based solutions as well as the energy storage performance by confining ions of aqueous electrolytes. Full article
Figures

Graphical abstract

Open AccessCommunication
Preparation of MgO-Templated N-Doped Mesoporous Carbons from Polyvinylpyrrolidone: Effect of Heating Temperature on Pore Size Distribution
Received: 7 March 2019 / Revised: 29 March 2019 / Accepted: 30 March 2019 / Published: 2 April 2019
Viewed by 492 | PDF Full-text (1327 KB) | HTML Full-text | XML Full-text
Abstract
Magnesium oxide (MgO)-templated nitrogen (N)-doped mesoporous carbons were prepared by using polyvinylpyrrolidone (PVP) as a raw material and magnesium lactate (Mglac) as a precursor for the MgO template to examine the influence of heating temperature and MgO precursor (magnesium acetate was used in [...] Read more.
Magnesium oxide (MgO)-templated nitrogen (N)-doped mesoporous carbons were prepared by using polyvinylpyrrolidone (PVP) as a raw material and magnesium lactate (Mglac) as a precursor for the MgO template to examine the influence of heating temperature and MgO precursor (magnesium acetate was used in similar previous studies) on the pore size and nitrogen content. The MgO-templated carbon was obtained by heating the PVP/Mglac mixture in an inert atmosphere followed by an acid treatment for MgO removal. The mesopore size of the carbons was approximately 4 nm regardless of heating temperature, corresponding to the crystallite size of the MgO template estimated via X-ray diffraction. This indicates that the mesopore of approximately 4 nm was generated using the MgO template. However, larger pores were also found to exist. This result indicates that the larger pores generated through processes other than the MgO templating, likely the thermal decomposition of PVP, are contained in the templated carbon. The volume of the larger pores and the specific surface area increased with increasing heating temperature. The nitrogen content of the carbon decreased as the heating temperature was increased, but it was found to be irrelevant to the MgO precursor. Full article
(This article belongs to the Special Issue Nitrogen-Doped Carbon Materials)
Figures

Graphical abstract

Open AccessArticle
RKKY Interaction in Graphene at Finite Temperature
Received: 27 February 2019 / Revised: 22 March 2019 / Accepted: 26 March 2019 / Published: 31 March 2019
Viewed by 569 | PDF Full-text (266 KB) | HTML Full-text | XML Full-text
Abstract
In our publication from eight years ago (Kogan, E. 2011, vol. 84, p. 115119), we calculated Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction between two magnetic impurities adsorbed on graphene at zero temperature. We show in this short paper that the approach based on Matsubara formalism and [...] Read more.
In our publication from eight years ago (Kogan, E. 2011, vol. 84, p. 115119), we calculated Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction between two magnetic impurities adsorbed on graphene at zero temperature. We show in this short paper that the approach based on Matsubara formalism and perturbation theory for the thermodynamic potential in the imaginary time and coordinate representation which was used then, can be easily generalized, and calculate RKKY interaction between the magnetic impurities at finite temperature. Full article
Figures

Graphical abstract

C EISSN 2311-5629 Published by MDPI AG, Basel, Switzerland RSS E-Mail Table of Contents Alert
Back to Top