Nanostructured Carbon Materials Research Articles

MoS2-Decorated Graphene@porous Carbon Nanofiber Anodes via Centrifugal Spinning.

Sodium-ion batteries (SIBs) are promising alternatives to lithium-ion batteries as green energy storage devices because of their similar working principles and the abundance of low-cost sodium resources. Nanostructured carbon materials are attracting great interest as high-performance anodes for SIBs. Herein, a simple and fast technique to prepare carbon nanofibers (CNFs) is presented, and the effects of carbonization conditions on the morphology and electrochemical properties of CNF anodes in Li- and Na-ion batteries are investigated. Porous CNFs containing graphene were fabricated via centrifugal spinning, and MoS2 were decorated on graphene-included porous CNFs via hydrothermal synthesis. The effect of MoS2 on the morphology and the electrode performance was examined in detail. The results showed that the combination of centrifugal spinning, hydrothermal synthesis, and heat treatment is an efficient way to fabricate high-performance electrodes for rechargeable batteries. Furthermore, CNFs fabricated at a carbonization temperature of 800 °C delivered the highest capacity, and the addition of MoS2 improved the reversible capacity up to 860 mAh/g and 455 mAh/g for Li- and Na-ion batteries, respectively. A specific capacity of over 380 mAh/g was observed even at a high current density of 1 A/g. Centrifugal spinning and hydrothermal synthesis allowed for the fabrication of high-performance electrodes for sodium ion batteries.

Detection and Isolation of Isomerically Pure C120 Fullertubes

The emergence of macroscopic amounts of C60 fullerenes and carbon nanotubes in the 1990s has led to an explosion of growth in new structures of carbon nanomaterials. Over the last decades, there have been theoretical predictions of a particular “hybrid” family of mathematical structures. Fullertubes represent a new area of fundamental research in molecular carbon. They are similar to fullerenes in structure, but with increasingly long cylindrical, single-wall nanotube belts in the middle of the molecules. These nanotube belts are similar to single-layer, rolled graphene. In 2020 we published the isomeric separation and characterization of [5,5] C90-D5h fullertubes and [5,5] C100-D5d fullertubes. In this presentation, we will report and discuss the first isolation and UV-vis characterization of pristine and unfunctionalized C120 fullertubes. The separation and isolation of larger fullertubes is a two-step purification process. First, the spheroidal fullerene contaminants must be removed from the carbon soot extract to enrich the sample in fullertubes. Then in the second step, HPLC is used to achieve isomerically purified and pristine fullertubes. Efforts to characterize these newly isolated C120 fullertubes are currently underway.

Sugar-Derived Isotropic Nanoscale Polycrystalline Graphite Capable of Considerable Plastic Deformation.

Obtaining large plastic deformation in polycrystalline van der Waals (vdW) materials is challenging. Achieving such deformation is especially difficult in graphite because it is highly anisotropic. The development of sugar-derived isotropic nanostructured polycrystalline graphite (SINPG) is discussed herein. The structure of this material preserves the high in-plane rigidity and out-of-plane flexibility of graphene layers and enables prominent plasticity by activating the rotation of nanoscale (5-10nm) grains. Thus, micrometer-sized SINPG samples demonstrate enhanced compressive strengths of up to 3.0GPa and plastic strains of 30-50%. These findings suggest a new pathway for enabling plastic deformation in otherwise brittle vdW materials. This new class of nanostructured carbon materials is suitable for use in a broad range of fields, from semiconductor to aerospace applications.

Voltammetric Assessment of 8-Oxoguanine at a Nano-Structured Carbon Materials Based Modified Glassy Carbon Electrode

In this study, we have investigated the voltammetric behavior of 8-Oxoguaine on a Multi walled carbon nanotubes / Carbon black modified glassy carbon electrode. The voltammetric oxidation of 8-Oxoguaine on modified electrode was electro-catalytic in nature. The voltammetric oxidation of the substrate was a pH dependent reversible process. Using cyclic voltammetry, a method for the determination of 8-Oxoguaine was developed. At a pH of 7.4 in phosphate buffer solution, the concentration of 8-Oxoguanine was linear from 30 to 100 μM. The detection limit and quantification limit of 8.38 μM and 27.95 μM were obtained from calibration graph, respectively. The modified electrode shows good recovery and reproducibility with relative standard deviation of 2.12%. The inter-day and intra-day assays were also studied.

Pulsed laser deposition of carbon nanofoam

We present a comprehensive study about the fabrication of porous, fractal-like nanostructured carbon materials, known as carbon nanofoam, through the Pulsed Laser Deposition (PLD) technique with nanosecond (ns-PLD) and femtosecond (fs-PLD) laser pulses ablating a pyrolitic graphite target. Carbon nanofoams have attracted considerable interest for applications of great societal and technological relevance. Among different fabrication methods, PLD emerged as a versatile tool that allows the depositon of nanostructured films on virtually any kind of substrate. Here we investigate the role of key PLD parameters (laser pulse duration and fluence, background gas pressure) on nanofoam characteristics, with a specific focus on how fractal aggregate properties at the nanometric scale (nanoparticle size, fractal dimension, gyration radius) determine nanofoam averaged properties such as density and uniformity. We performed systematic deposition campaigns and characterizations through experimental analysis and mathematical models. Moreover, a first-of-its-kind comparison between ns-PLD and fs-PLD regimes is drawn. We discuss the physics of foam growth in both regimes, and we propose an analytical model based on the fractal scaling law to predict the nanofoam density from aggregates’ properties. The new insights gained about deposition and characterization of carbon nanofoam open new perspectives in fabrication of nanostructured films with precisely controlled properties.

Nano-Structured Carbon: Its Synthesis from Renewable Agricultural Sources and Important Applications.

Carbon materials are versatile in nature due to their unique and modifiable surface and ease of production. Nanostructured carbon materials are gaining importance due to their high surface area for application in the energy, biotechnology, biomedical, and environmental fields. According to their structures, carbon allotropes are classified as carbon nanodots, carbon nanoparticles, graphene, oxide, carbon nanotubes, and fullerenes. They are synthesized via several methods, including pyrolysis, microwave method, hydrothermal synthesis, and chemical vapor deposition, and the use of renewable and cheaper agricultural feedstocks and reactants is increasing for reducing cost and simplifying production. This review explores the nanostructured carbon detailed investigation of sources and their relevant reports. Many of the renewable sources are covered as focused here, such as sugar cane waste, pineapple, its solid biomass, rise husk, date palm, nicotine tabacum stems, lapsi seed stone, rubber-seed shell, coconut shell, and orange peels. The main focus of this work is on the various methods used to synthesize these carbon materials from agricultural waste materials, and their important applications for energy storage devices, optoelectronics, biosensors, and polymer coatings.

A biomass-based hierarchical carbon via MOFs-assisted synthesis for high-rate lithium-ion storage

A hierarchical nanostructured biomass-based carbon material derived from banana peels slurry and ZIF-8 hybrids (HNBZC) is introduced with excellent lithium-ion storage and rate capability. HNBZC was prepared through a hollow MOFs-assisted hard template strategy, in which we can easily control the pore size and doping element content to further improve the electrochemical performance of biomass-based carbon. HNBZC can reversibly deliver a capacity of 620 mAh g−1 at current densities of 20 mA g−1, and 61 mAh g−1 is still obtained at a high current density of 50 A g−1. Furthermore, a capacity retention ratio of 80% is achieved after 780 cycles at 5 A g−1. Our results indicate a promising method to obtain a carbon material with enhanced electrochemical performance based on natural biomass waste.

A Top-Down Templating Strategy toward Functional Porous Carbons.

Nanostructured carbon materials with high porosity and desired chemical functionalities are of immense interest because of their wide application potentials in catalysis, environment, and energy storage. Herein, a top-down templating strategy is presented for the facile synthesis of functional porous carbons, based on the direct carbonization of diverse organic precursors with commercially available metal oxide powders. During the carbonization, the metal oxide powders can evolve into nanoparticles that serve as in situ templates to introduce nanopores in carbons. The porosity and heteroatom doping of the prepared carbon materials can be engineered by varying the organic precursors and/or the metal oxides. It is further demonstrated that the top-down templating strategy is applicable to prepare carbon-based single-atom catalysts with iron-nitrogen sites, which exhibit a high power density of 545mW cm-2 in a H2 -air proton exchange membrane fuel cell.

P-functionalized carbon nanotubes promote highly stable electrocatalysts based on Fe-phthalocyanines for oxygen reduction: Experimental and computational studies

Iron(II) phthalocyanines (FePc) supported on functionalized nanostructured carbon materials have been studied as electrocatalysts for the oxygen reduction reaction (ORR) in an alkaline medium. Herein, two types of carbon nanotubes (CNTs) have been explored as support, Single-Walled Carbon Nanotubes and Herringbone Carbon Nanotubes (SWCNTs and hCNTs, respectively), both electrochemically modified with ortho- aminophenylphosphonic acid (2APPA), which provides phosphate axial coordinating ligands for the immobilization of FePc molecules. All the catalysts were prepared via a facile incipient wetness impregnation method. Comprehensive experimental analysis together with density functional theory (DFT) calculations has demonstrated both the importance of the five-coordinated Fe macrocycles that favor the interaction between the FePc and the carbon support, as well as the effect of the CNT structure in the ORR. FePc axial coordination provides a better dispersion, leading to higher stability and a favorable electron redistribution that also tunes the ORR performance by lowering the stability of the reaction intermediates. Interestingly, such improvement occurs with a very low content of metal (∼1 wt% Fe), which is especially remarkable when hCNT support is employed. This work provides a novel strategy for the development of Fe-containing complexes as precious metal-free catalysts towards the ORR.

New Fourtitude FCC catalyst maximizes butylenes helping to improve performance for refiners

For the last two decades, environmental pollution has been an alarming issue for the scientific community. The majority of researchers are working on this issue in order to control the magnitude of pollution by proposing suitable techniques using advanced materials. In order to combat pollution, initially we have to estimate the extent of pollution with respect to specific pollutants. This can be done using diverse analytical techniques available, like electrochemical, optical, and instrumental based. In order to enhance the selectivity and sensitivity of analytical techniques, nanomaterials have been explored extensively. Among the diverse nanomaterials available, carbon nanomaterials have been used extensively as sensing materials in various analytical techniques. This may be due to their diverse structural features and array of interesting electrical, optical and magnetic properties. Furthermore, their incomparable chemistry with other elements, ease of their surface modification, simple synthetic procedures, natural abundance, and cost-effectiveness make them as favorite materials for researchers and environmental chemists to use as sensor substrates. Among various structured carbon nanomaterials, nanotubes, graphene, and quantum dots have been explored as sensor materials in both electrochemical and optical techniques. In this report, we are aimed at synthesis and development of optical and analytical protocols based on recent nanostructured carbon materials used for environmental sensor applications.

Roles of Biomass in the Absorption of Heavy Metals

Mining, plating, dyeing, automobile manufacturing, and metal processing all emit toxic heavy metals into the environment. The environmental challenges, socioeconomic and environmental effects of toxic heavy metals released into the environment cause environmental problems that have exposed our ecosystem to a greater threat, as well as contamination of aquatic water bodies through water runoff, with a subsequent effect on people's health. As a result, research into the roles of biomass as a mitigation process in heavy metal absorption is required. As a result, the purpose of this paper is to investigate the roles of biomass as a medium for heavy metal absorption in contaminated soil. The use of bio-char and other carbonaceous materials such as activated carbon, sawdust, and agricultural residues has shown great potential for the removal of various inorganic and organic pollutants and radionuclides due to properties such as large surface area, micro porous structure, and high adsorption capacity. Pulverized activated charcoal, a promising material based among nano-structured carbon materials, continues to attract a lot of attention due to its unique physical and chemical properties. Lower greenhouse gas emissions and a cleaner environment are two additional environmental benefits of biomass as a renewable energy source. The importance of biomass as a potential natural remediation material cannot be overstated based on the use of biomass waste to treat or resolve anthropogenic environmental problems.

Graphene-based Nanocomposites for Automotive and Off-highway Vehicle Applications: A Review

Abstract: Abstract Abstract: Nanocomposites comprised of a polymer matrix and various types of nanosized fillers have remained one of the most important engineering materials and continue to draw great interest in the research community and industry. In particular, graphene in nanocomposites that possess high thermal conductivity and excellent mechanical, electrical, and optical properties have turned out to be promising fillers for making the next generation of advanced high-performance materials. Though large-scale production of graphene-based nanocomposites is a bit challenging due to the mechanical, functional, and interfacial properties of the graphene and polymer matrix under severe loading conditions, the automotive and off-highway machinery industries are expected to utilize the most modern composite materials, such as graphene-based nanocomposites, to create lighter, stronger, safer, and more energy-efficient cars in the future. Graphene-based material strategies have been investigated and demonstrated to be effective for structural applications in various industries, including electronics, electromechanical, and energy systems. However, currently, there is only limited research highlighting the specific knowledge available for design engineers and researchers involved in providing lightweight but strong solutions using graphene-based materials for automotive and off-highway vehicle applications. The present review presents an overview of the latest studies that utilize graphene-based nanomaterials and their composites in automotive and off-highway machinery applications. First, the paper describes the concept of traditional composites used presently in the engineering industries by considering its advantages and limitations. Then, it highlights the key benefits of using nanostructured carbon materials, such as graphene, through some recent studies available in the literature. Subsequently, it depicts the various mechanisms of integrating graphene as polymer reinforcements within the composite materials based on the survey and their related modelling, designing, and manufacturing capabilities suitable for the automotive and off-highway machinery industry. Finally, it outlines the available experimental evidence for graphene-based composites. To lay the groundwork for future work in this exciting area, the paper discusses the current challenges as well as future prospects in the field.

Effects of Annealing Temperature on the Size of Zinc Doped Cobalt Ferrite Nanoparticles Synthesized using Green Binder

This review highlights the different strategies of modified TiO2 nanostructure as heterogeneous catalyst in organic transformations. The modification in TiO2 nanostructure have been achieved by doping with metal and non-metal, composing with other material such as metals, metal oxides, nonoxides, semiconductor and nanostructure carbon materials. The influence of modification in TiO2 nanostructure on catalytic properties in organic synthesis also discussed. Different modifications of TiO2 extend the catalyst selectivity and reusability over unmodified TiO2 nanoparticles. Recent investigations have shown that modified TiO2 nanostructures utilised as active catalysts or catalyst support in organic transformations including C-C, C-N, C-S, C-O bond formation reactions, multicomponent reactions (MCR), oxidation- reductions.

Recent Advances of Modified TiO2 Nanostructure as Heterogeneous Catalyst in Organic Transformations

This review highlights the different strategies of modified TiO2 nanostructure as heterogeneous catalyst in organic transformations. The modification in TiO2 nanostructure have been achieved by doping with metal and non-metal, composing with other material such as metals, metal oxides, nonoxides, semiconductor and nanostructure carbon materials. The influence of modification in TiO2 nanostructure on catalytic properties in organic synthesis also discussed. Different modifications of TiO2 extend the catalyst selectivity and reusability over unmodified TiO2 nanoparticles. Recent investigations have shown that modified TiO2 nanostructures utilised as active catalysts or catalyst support in organic transformations including C-C, C-N, C-S, C-O bond formation reactions, multicomponent reactions (MCR), oxidation- reductions.

Visible-Light Assisted Covalent Surface Functionalization of Reduced Graphene Oxide Nanosheets with Arylazo Sulfones.

We present an environmentally benign methodology for the covalent functionalization (arylation) of reduced graphene oxide (rGO) nanosheets with arylazo sulfones. A variety of tagged aryl units were conveniently accommodated at the rGO surface via visible-light irradiation of suspensions of carbon nanostructured materials in aqueous media. Mild reaction conditions, absence of photosensitizers, functional group tolerance and high atomic fractions (XPS analysis) represent some of the salient features characterizing the present methodology. Control experiments for the mechanistic elucidation (Raman analysis) and chemical nanomanipulation of the tagged rGO surfaces are also reported.

Scaling up the Process of Catalytic Decomposition of Chlorinated Hydrocarbons with the Formation of Carbon Nanostructures

Catalytic processing of organochlorine wastes is considered an eco-friendly technology. Moreover, it allows us to obtain a value-added product—nanostructured carbon materials. However, the realization of this process is complicated by the aggressiveness of the reaction medium due to the presence of active chlorine species. The present research is focused on the characteristics of the carbon product obtained over the Ni-Pd catalyst containing 5 wt% of palladium in various quartz reactors: from a lab-scale reactor equipped with McBain balance to scaled-up reactors producing hundreds of grams. 1,2-dichloroethane was used as a model chlorine-substituted organic compound. The characterization of the materials was performed using scanning and transmission electron microscopies, Raman spectroscopy, and low-temperature nitrogen adsorption. Depending on the reactor type, the carbon yield varied from 14.0 to 24.2 g/g(cat). The resulting carbon nanofibers possess a segmented structure with disordered packaging of the graphene layers. It is shown that the carbon deposits are also different in density, structure, and morphology, depending on the type of reactor. Thus, the specific surface area changed from 405 to 262 and 286 m2/g for the products from reactor #1, #2, and #3, correspondingly. The main condition providing the growth of a fluffy carbon product is found to be its ability to grow in any direction. If the reactor walls limit the carbon growing process, the carbon product is represented by very dense fibers that can finally crack the reactor.

Hydrogen Bond Donors Influence on the Electrochemical Performance of Composite Graphene Electrodes/Deep Eutectic Solvents Interface

The development of energy storage devices with better performance relies on the use of innovative materials and electrolytes, aiming to reduce the carbon footprint through the screening of low toxicity electrolytes and solvent-free electrode design protocols. The application of nanostructured carbon materials with high specific surface area, to prepare composite electrodes, is being considered as a promising starting point towards improving the power and energy efficiency of energy storage devices. Non-aqueous electrolytes synthesized using greener approaches with lower environmental impact make deep eutectic solvents (DES) promising alternatives for electrochemical energy storage and conversion applications. Accordingly, this work proposes a systematic study on the effect of the composition of DES containing a diol and an amide as HBD (hydrogen bond donor: 1,2-propylene glycol and urea), on the electrochemical performance of graphene and graphite composite electrodes/DES electrolyte interface. Glassy carbon (GC) was selected as the bare electrode material substrate to prepare the composite formulations since it provides an electrochemically reproducible surface. Gravimetric capacitance was measured for commercial graphene and commercial graphite/GC composite electrodes in contact with choline chloride, complexed with 1,2-propylene glycol, and urea as the HBD in 1:2 molar ratio. The electrochemical stability was followed by assessing the charge/discharge curves at 1, 2, and 4 A g−1. For comparison purposes, a parallel study was performed using commercial graphite. A four-fold increase in gravimetric capacitance was obtained when replacing commercial graphite (1.70 F g−1) by commercial graphene (6.19 F g−1) in contact with 1,2-propylene glycol-based DES. When using urea based DES no significant change in gravimetric capacitance was observed when commercial graphite is replaced by commercial graphene.

Micro/nano-structure construct of carbon fibers reinforced graphene/CNT matrix composites for Li-S batteries

Lithium‑sulfur (Li-S) batteries have been hindered by the difficulty of achieving satisfactory cycling stability of high sulfur loading owing to the structural instability and exaggerated shuttle problem. Here, we design and fabricate a “reinforced concrete” structure based on the carbon fibers (CFs) supporting graphene/carbon nanotubes (GC) matrix composites, followed by a slurry-casting process to produce the final CFs-S/GC cathode with 4.5– 5.5 mg cm−2 sulfur loading. The 3D architecture of the micro/nano-hybrid materials enhances the structural strength and builds an interconnected conductive network for efficient electrolyte infiltration and the rapid electric/ionic transport. Furthermore, carbon nanofibers (CNFs) are growth on the surface of CFs by chemical vapor deposition to formation of CFs@CNFs. The CFs@CNFs-S/GC cathode enables the effective confines of polysulfides on electrochemically active sites, leading to a much-improved cycling performance. The strategy reported in this paper provides a feasible way for the construction of CFs or modified CFs skeleton in nanostructured carbon materials for high energy density Li-S batteries.

Analysis of the dispersion state of pitch particles in polymers for nanofiber fabrication by optical microscopy and image processing

The polymer blend method is one of the most useful approaches for mass-producing carbon nanotubes and carbon nanofibers. In order to make such nanostructured carbon materials, it is important to understand the dispersion state of the carbon precursor polymer (CPP) in the thermally decomposable polymer (TDP) prior to spinning. In this study, pitch particles have been used as the CPP. Analysis methods of the dispersion of pitch particles in the polymer based on optical microscopy and image processing have been studied. Polished cross-sections of polymers with embedded pitch particles have been observed by polarization microscopy. The microscope images were then transformed into binary images. The centers of gravity of the cross-sections of the pitch particles have been calculated to measure the minimum distances between particles. Fractal analysis has also been applied to estimate the dispersion of the particles. To analyze the spatial frequencies of the particle distribution, two-dimensional fast Fourier transform (2D-FFT) has been applied to the cross-sectional images. Spatial frequency analysis has provided a measure of the distances between particles and of their clustering. The dispersion state of the particles could thereby be gleaned.

Сорбционные свойства графенового аэрогеля по отношению к метану

A new nanostructured carbon material is synthesized, which represents aerogel based on reduced graphene oxide. Aerogel obtained by using supercritical methods for processing a hydrogel in isopropyl alcohol. Resulting material has sufficiently high specific surface in terms of BET — 657 m2/g with high specific pore volume DFT — 0.766 cm3/g, which creates good prospects for its use for the adsorption of energetically important gases, in particular methane. A favorable factor for increasing the rate of adsorption-desorption in such systems is the large volume of mesopores with diameters of about 4.5 – 6.5 nm. Adsorption of methane at temperatures of 298.15, 303.15, 313.15 K and pressures up to 100 bar was studied on the synthesized graphene aerogel. The maximum value of methane adsorption under temperature 298.15 K and pressure of 100 bar reaches 7.31 mmol/g. The characteristic parameters of the adsorption process were analyzed using the empirical models of the Langmuir and Freundlich isotherms. The adsorption process was investigated at the level of evaluating thermodynamic parameters, which indicate its change from a random state to an ordered one, and its exothermic and physical nature. The obtained results can be used in the design of storage systems for adsorbed natural gas.