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Recently, the preparation of some hematene and magnetene ultrathin non van der Waals (non‐vdW) 2D nanoplatelets was reported starting from hematite and magnetite natural iron ores. The present work reports on the determination and evaluation of the nonlinear optical response and the optical limiting (OL) action of these 2D nanoplatelets dispersed in water under ns laser excitation. The obtained results show that both hematene and magnetene exhibit strong nonlinear absorption and refraction, comparable and even larger than those of other van der Waals (vdW) 2D counterpart materials. In addition, due to their strong nonlinear absorption, both hematene and magnetene show exceptional OL performance from the UV to visible, attaining very low values of optical limiting onset (OLon), comparable and even lower than that of vdW 2D nanomaterials, such as graphene, graphene oxide, other transition metal dichalcogenides like MoS2, WS2 and MoSe2, black phosphorous and antimonene. Moreover, hematene was found to exhibit more efficient OL action than magnetene for all the excitation wavelengths studied, attributed to more efficient ligand to metal charge transfer. The present findings open new possibilities for the potential use of these non‐vdW 2D materials in photonics and optoelectronics, e. g., as optical limiters and optical switchers. [ABSTRACT FROM AUTHOR]

The preparation and characterization of highly conductive carbon inks is described based on nanocomposites that combine a polystyrene-acrylic resin or water-soluble polymers with a hydrophilic graphene/carbon nanotube hybrid. The water-based carbon inks showed high electrical conductivity and could be effectively used in advanced technologies such as gravure printing for printed electronics. Moreover, the conductivity was shown to be increased with a power law of the nanohybrid volume fraction, with an exponent close to that predicted from the percolation theory, indicating a limited impact of the polymer tunneling barrier on the electrical conductivity of such nanocomposites. [ABSTRACT FROM AUTHOR]

The effective entrapment of Carbon dots (CDs) into a polymer-silica hybrid matrix, formed as free standing transparent flexible films, is presented. The composite's synthesis, characterization, device application and properties -mechanical, thermal and optical- are being provided and discussed. CDs of 3 nm mean size with strong photoluminescence are embedded into a silica matrix during the sol-gel procedure, using tetraethyl orthosilicate as the precursor and F127 triblock copolymer as the structure directing agent under acidic conditions. The final hybrid nanostructure forms free standing transparent films that show high flexibility and long term stable CDs luminescence indicating the protective character of the hybrid matrix. It is crucial that the photoluminescence of the hybrid's CDs is not seriously affected after thermal treatment at 550 °C for 30 min. Moreover, the herein reported hybrid is demonstrated to be suitable for the fabrication of advanced photonic structures using soft lithography processes due to its low shrinkage and distortion upon drying, both attributable to its porosity. Finally, it is reported that addition of F127 ethanolic solution in aqueous solution of CDs induces a blue-shift of their photoluminescence. [ABSTRACT FROM AUTHOR]

Herein, the formation and selective organic derivatisation of graphene nanobud, an all carbon nanohybrid comprised by C 60 and graphene, are presented. C 60 cages are directly attached to the graphenic surface with stable covalent bonds. Importantly, prepared graphene nanobud shows remarkable dispersibility, decreased number of defects and highly aromatic character that are associated to improved electrical conductivity compared to pristine graphene. The high chemical reactivity of the curved sp 2 carbon atoms of C 60 led to a selective covalent attachment of organic groups onto C 60 avoiding damage of the graphene aromatic system. [ABSTRACT FROM AUTHOR]

This Review focuses on noncovalent functionalization of graphene and graphene oxide with various species involving biomolecules, polymers, drugs, metals and metal oxide-based nanoparticles, quantum dots, magnetic nanostructures, other carbon allotropes (fullerenes, nanodiamonds, and carbon nanotubes), and graphene analogues (MoS2, WS2). A brief description of π-π interactions, van der Waals forces, ionic interactions, and hydrogen bonding allowing noncovalent modification of graphene and graphene oxide is first given. The main part of this Review is devoted to tailored functionalization for applications in drug delivery, energy materials, solar cells, water splitting, biosensing, bioimaging, environmental, catalytic, photocatalytic, and biomedical technologies. A significant part of this Review explores the possibilities of graphene/graphene oxide-based 3D superstructures and their use in lithium-ion batteries. This Review ends with a look at challenges and future prospects of noncovalently modified graphene and graphene oxide. [ABSTRACT FROM AUTHOR]

In the recent advances in the field of conductive polymers, the fibrillar or needle shaped nanostructures of polyaniline and polypyrrole have attracted significant attention due to the potential advantages of organic conductors that exhibit low-dimensionality, uniform size distribution, high crystallinity and improved physical properties compared to their bulk or spherically shaped counterparts. Carrying the polymerization reaction in a restricted two dimensional space, instead of the three dimensional space of the one phase solution is an efficient method for the synthesis of polymeric nanostructures with narrow size distribution and small diameter. Ultra-thin nanowires and nanofibers, single crystal nanoneedles, nanocomposites with noble metals or carbon nanotubes and layered materials can be efficiently synthesized with high yield and display superior performance in sensors and energy storage applications. In this critical review we will focus not only on the interfacial polymerization methods that leads to polymeric nanostructures and composites and their properties, but also on the mechanism and the physico-chemical processes that govern the diffusion and reactivity of molecules and nanomaterials at an interface. Recent advances for the synthesis of conductive polymer composites with an interfacial method for energy storage applications and future perspectives are presented. [ABSTRACT FROM AUTHOR]

The article discusses the classification of carbon nanoallotropes, and its structural description, and characterization. It outlines several methods for preparing carbon nanostructures, and mentions the fundamental physicochemical properties of carbon nanoallotropes. It notes the interconversions of carbon nanoallotropes, and the combination of nanoarchitectures to produce advanced allotropic hybrids.

In this work, it is shown that the hydrophilic functionalized multiwall carbon nanotubes (MWCNs) can stabilize a large amount of pristine graphene nanosheets in pure water without the assistance of surfactants, ionic liquids, or hydrophilic polymers. Role of stabilizer is conveyed by highly hydrophilic carbon nanotubes, functionalized by dihydroxy phenyl groups, affording a stable dispersion at concentrations as high as 15 mg mL−1. Such multidimensional (2D/1D) graphene/MWCN hybrid is found to be dispersible also in other polar organic solvents such as ethanol, isopropanol, N, N-dimethylformamide, ethylene glycol, and their mixtures. High-resolution transmission microscopy and atomic force microscopy (AFM) including a liquid mode AFM manifest several types of interaction including trapping of multiwalled carbon nanotubes between the graphene sheets or the modification of graphene edges. Molecular dynamic simulations show that formation of an assembly is kinetically controlled. Importantly, the hybrid can be deposited on the paper by drop casting or dispersed in water-soluble polymers resulting in record values of electrical conductivity (sheet resistance up to Rs ≈ 25 Ω sq−1 for free hybrid material and Rs ≈ 1300 Ω sq−1 for a polyvinilalcohol/hybrid composite film). Thus, these novel water dispersible carbon superstructures reveal a high application potential as conductive inks for inkjet printing or as highly conductive polymers. [ABSTRACT FROM AUTHOR]

The hydroxyphenyl derivatives of carbon nanostructures (graphene and carbon nanotubes) can be easily transformed into highly organophilic or hydrophilic derivatives by using the ionic interactions between the phenolic groups and oleylamine or tetramethylammonium hydroxide, respectively. The products were finely dispersed in homo-polymers or block co-polymers to create homogeneous carbon-based nanocomposites and were used as nanocarriers for the dispersion and protection of strongly hydrophobic compounds, such as large aromatic chromophores or anticancer drugs in aqueous solutions. [ABSTRACT FROM AUTHOR]

The article presents a study which investigates the functionalization of graphene. The study used several methods including the deposition of the metal oxide nanoparticles, quantum dot deposition, and substitutional doping. Study reveals that the performance of the nanoparticle materials of graphene depends highly on the architecture of nanoscale building blocks.

Ultrathin carbon nanosheets (CNSs) were functionalized using 1,3 dipolar cycloaddition of azomethine ylide. The organic modification of carbon nanosheets with hydroxyl groups on the external graphene layers facilitates the dispersion in polar solvents including water and thus the incorporation of the derivatives in other matrices such as polymers. [ABSTRACT FROM AUTHOR]

Abstract: Treatment of crystalline graphite fine powder with an aqueous solution of the harmless and versatile substance polyvinylpyrrolidone under sonication results in water-soluble, polymer-protected graphene single layers without oxidation or destruction of the sp2 character of the carbon core. The liquid-phase extraction of graphene monolayers was evidenced by TEM and AFM techniques, while their graphitic character was checked with Raman spectroscopy. Besides PVP, the water-soluble biopolymers albumin and sodic carboxymethylcellulose were also employed successfully in the aqueous-phase exfoliation of graphite, thereby supporting the generic character of the present method using a variety of suitable polymeric extractants. [Copyright &y& Elsevier]

Abstract: Polypyrrole/carbon nanotubes (CNTs) composites were synthesized by dispersion of organically modified multiwall carbon nanotubes during an interfacial polymerization of pyrrole. During the polymerization, the carbon nanotubes are entrapped by the polymer chains and the nanocomposite is formed in the interphase between two immiscible solvents. The method favours a better dispersion of the nanotubes in the polypyrrole offering enhanced electrical properties. The characterisation of the composite material has been established by XRD, TGA analysis and electron microscopy techniques. [Copyright &y& Elsevier]

Abstract: Graphite fluoride has been generally considered chemically inert against strong alkalis under ambient conditions. In the present study we demonstrate that treatment of graphite fluoride with eutectic NaOH–KOH mixture at 250°C induces dramatic structural and textural changes in the solid as evidenced by XRD, FT-IR, Raman, UV–vis absorption and fluorescence and microscopy techniques (TEM, AFM). The reaction proceeds in the molten state leading to water-soluble, graphitized carbon particles which unlike graphite fluoride, adopt a variety of morphologies, like platy, tetragonal, triangular, discoid and spherical. The resulting carbon particles are dispersible in water and fluoresce under UV excitation. [Copyright &y& Elsevier]

We show that covalent functionalization of carbon nanotubes (CNTs) via 1,3-dipolar cycloaddition is a powerful method for enhancing the ability to process CNTs and facilitating the preparation of hybrid composites, which is achieved solely by mixing. CNTs were functionalized with phenol groups, providing stable dispersions in a range of polar solvents, including water. Additionally, the functionalized CNTs could easily be combined with polymers and layered aluminosilicate clay minerals to give homogeneous, coherent, transparent CNT thin films and gels. [ABSTRACT FROM AUTHOR]

Abstract: Single-walled carbon nanotubes (SWNTs) were decorated with Au, Pt and Rh nanoparticles coated with oleylamine. This modification improves substantially the colloidal dispersion of SWNTs in chloroform and other organic solvents affording stable organosols for realistic applications. The metal nanoparticles are well dispersed on the external surfaces of carbon nanotubes and among else could be used as catalyst in homogeneous or heterogeneous reactions. [Copyright &y& Elsevier]

Three fulleropyrrolidine derivatives, characterized by the presence of positive charges, were introduced in the interlayer space of montmorillonite. The composites were characterized by powder X-ray diffraction and differential thermal and thermogravimetric (DTA-TGA) analysis, in conjunction with FTIR, UV-Vis, Raman, and 57Fe-Mössbauer spectroscopies. Organophilic derivatives were intercalated into organically modified clays, while water-soluble fulleropyrrolidines were introduced into the clay galleries through ion exchange. The experiments, complemented by computer simulations, show that not all the clay-clay platelets are intercalated by the fullerene derivatives and that a sizable amount of charge transfer takes place between the host and the guests. [ABSTRACT FROM AUTHOR]

Single-walled carbon nanotubes were derivatized by the catalytic action of aluminosilicate minerals. Hydrothermal treatment of carbon nanotubes with clay and an aliphatic acid gave side alkylated carbon nanotubes-clay composites, which could be of value in various technological applications. XRD pattern indicates that alcylated carbon nanotubes are intercalated between the clay layers. Following acid demineralization, functionalized carbon nanotubes were obtained and characterized. [Copyright &y& Elsevier]

Examines the supramolecular self-assembly of fullerene nanostructures. Formation of spheres, nanorods and nanotubules in water; Use of electron microscopy in imaging different nanostructures; Fabrication of uniformly-shaped nanotubular crystals.

The synthesis of p-acetyl and p-benzoyl derivatives of various benzylsilanes (p-R1CO–C6H4–CR2R3–SiMe3: R1, R2, R3=Me, H, H; Me, H, Ph; Me, H, Me; Me, Me, Me; Ph, H, H; Ph, H, Ph; Ph, H, Me; Ph, Me, Me), xanthenes (3-benzoyl and 3,6-dibenzoyl), and 9-Me3Si-xanthenes (3-benzoyl, 3,6-dibenzoyl, 3-acetyl and 3,6-diacetyl) using Friedel–Crafts reactions and typical Lewis acid catalysts (AlCl3, FeCl3, ZnCl2) is described. Desilylation side reactions caused by AlCl3 become significant in substrates with weak carbon–silicon bonds (e.g. Ph2CH–SiMe3), and in the case of Ph3C–SiMe3 only the desilylation product Ph3CH was isolated. [Copyright &y& Elsevier]

This work provides a method for the development of conductive water-based printing inks for gravure, flexography and screen-printing incorporating commercial resins that are already used in the printing industry. The development of the respective conductive materials/pigments is based on the simultaneous (in one step) reduction of silver salts and graphene oxide in the presence of 2,5-diaminobenzenesulfonic acid that is used for the first time as the common in-situ reducing agent for these two reactions. The presence of aminophenylsulfonic derivatives is essential for the reduction procedure and in parallel leads to the enrichment of the graphene surface with aminophenylsulfonic groups that provide a high hydrophilicity to the final materials/pigments. [ABSTRACT FROM AUTHOR]

The rapidly increased interest in multifunctional nanoelectronic devices, such as wearable monitors, smart robots, and electronic skin, motivated many researchers toward the development of several kinds of sensors in recent years. Flexibility, stability, sensitivity, and low cost are the most important demands for exploiting stretchable or compressible strain sensors. This article describes the formation and characteristics of a flexible, low-cost strain sensor by combining a commercial melamine sponge and a graphene/carbon nanotubes hybrid. The composite that emerged by doping the highly elastic melamine sponge with a highly conductive graphene/carbon nanotubes hybrid showed excellent piezoresistive behavior, with low resistivity of 22 kΩ m. Its function as a piezoresistive material exhibited a high sensitivity of 0.050 kPa−1 that combined with a wide detection area ranging between 0 to 50 kPa. [ABSTRACT FROM AUTHOR]

Abstract: Fullerol-carbon nanotube hybrids have been fabricated through wet impregnation of oxidized multi-wall carbon nanotubes with fullerols and subsequent solid-state heating at 200°C to promote interfacial bonding. Because fullerols attach to the walls as polyanions providing static repulsion, the hybrid displays high aqueous solubility. The decoration of the nanotubes with fullerols was established by infrared spectroscopy and atomic force microscopy, whereas its impact on the surface properties was studied by means of zeta-potential measurements and dynamic light scattering. [Copyright &y& Elsevier]

Organically modified carbon nanotubes serve as intermediate substrate for further functionalization with a perfluoroalkylsilane toward a superhydrophobic core–shell hybrid that is additionally soluble in certain solvents. On account of these properties, the hybrid can be easily blended with polymers or impregnated on the surface of textiles, also rendering them superhydrophobic. [ABSTRACT FROM AUTHOR]

The interest in the research for transparent conductive materials has intensified the last years due to the fascinating optical and electrical properties of graphene and its derivatives. Several efforts have shown that the substitution of indium doped tin oxide with graphene derivatives or hybrids will be possible in the near future. However, up to now, a simple and effective method to prepare competitive transparent conductive films (TCFs) based on graphene has not yet been established. In this article, we present a new procedure, which combines simple, economic and scalable steps to provide TCFs with high quality, uniformity, and stability. Our method is based on the deposition by drop casting, of a mixture of graphene oxide (GO) with polyvinyl alcohol on a glass substrate, the reduction of GO with vapors of triethylenetetramine and the doping with nitric acid. The achieved conductivity of the as prepared TCFs is comparable with those of others from the literature, however, our method has the advantages of the simplicity, low cost and scalability, and stability. [ABSTRACT FROM AUTHOR]

A green approach for the functionalization of multiwalled carbon nanotubes (MWNTs) with hydrophilic groups and their use for the development of an ecofriendly conductive ink are described here. A known organic functionalization of MWNTs, 1,3 dipolar cycloaddition of catechol substituted azomethine ylide, is performed here for the first time, in the solid phase. The functionalized MWNTs were then mixed with graphene nanosheets in ethanol to produce a hydrophilic and highly conductive all-carbon hybrid. The end product was finally mixed with resin to produce a water based conductive ink. In the total procedure, a solid state reaction and non-toxic and eco-friendly solvents like water or alcohols have been used to produce a totally green conductive ink for industrial printing techniques like flexography or gravure printing. [ABSTRACT FROM AUTHOR]

Carbon paper‐supported graphene aerogels are examined as anode electrodes for lithium‐ion batteries, employing a hydrothermal process and a freeze‐drying step. Triethylenetetramine (TETA) and o‐phenylenediamine (OPD) prove to promote graphene aerogel formation and its chemical bonding onto the surface of carbon paper. The electrochemical results demonstrate that the electrode treated with the former diamine has a remarkable rate capability with higher capacities as compared with the electrode treated with the latter diamine and better stability. [ABSTRACT FROM AUTHOR]

In this article, the enrichment of graphene and graphene oxide with free radicals through their functionalization with tyrosine is studied. In contrast with what is commonly observed in the functionalization of graphene with organic species the addition of tyrosine radicals on to the graphene substrate led to a remarkable increase of the aromatic character as indicated by the spectroscopic data. Similar behaviour was observed for the functionalization of graphene oxide. In addition, a brief analysis of the tyrosine functionalized graphene with EPR spectroscopy showed a remarkable enhancement of the spin density that could be useful in spintronics. [ABSTRACT FROM AUTHOR]

The interfacial asymmetric post‐functionalization of graphene nanosheets and their self‐assembly into superstructures is presented. By performing two sequential functionalizations, graphene nanosheets lying in the interface of a biphasic aqueous‐organic system become amphiphilic, thereby generating an organophilic side and a hydrophilic side. The as‐prepared Janus type amphiphilic graphene nanosheets are then self‐assembled to generate different interesting superstructures, depending on the nature of the solvent in which they are dispersed. Turn the other face: Catechol‐enriched graphene was post‐functionalized asymmetrically at the interface of a water–chloroform biphasic system (see figure). By using two amines in the produced amphiphilic Janus type graphene, different superstructures can form when it is dispersed in chloroform or water. [ABSTRACT FROM AUTHOR]

This article presents a study related to organic functionalization and optical properties of carbon onions which was conducted as of November 26, 2003. The arc discharge experiments, developed in recent years to produce large quantities of carbon allotropes, yield fullerenes and nanotubes as the most abundant species. The study reports, for the first time, a method for chemically functionalizing onions from arc discharge soots. The new methodology not only allows the isolation of giant fullerenes, but especially renders them soluble in organic solvents, such that their solution properties can be studied.

Discusses the purification of single-walled carbon nanotubes (SWNT) through organic functionalization. Key steps in the purification processes; Oxidative treatment of SWNT; Organic functionalization of SWNT based on the 1,3 dipolar cycloaddition of azomethine ylides.

Examines the effects of nanostructure materials on the organic solvents. Solubilization of carbon nanotubes; Formation of alkyl chains and polymers; Condensation of alpha-amino acids.

Water dispersible graphene functionalized with hydrophilic carbon nanotubes. The image demonstrates molecules of water, which surround carbon superstructures providing various modes of graphene‐nanotube interaction. On page 1481, V. Georgakilas, R. Zbořil, and co‐workers show that such a graphene hybrid is dispersible in many polar solvents and displays excellent electrical conductivity, offering a great potential in highly conductive polymers or inkjet printing technologies. [ABSTRACT FROM AUTHOR]

In this work, UV-curable resin poly (ethylene glycol) diacrylate (PEGDA) was reinforced with three different types of nanofillers: pristine graphene (G), multiwalled carbon nanotubes (MWNTs), and a hybrid of MWNTs and graphene 70/30 in mass ratio (Hyb). PEGDA was mixed homogenously with the nanofiller oligomer by shear mixing and then photopolymerized, affording thin, stable films. The thermomechanical properties of the afforded nanocomposites indicated the superior reinforcing ability of pristine graphene compared with MWNTs and an intermediate behavior of the hybrid. [ABSTRACT FROM AUTHOR]

Simple Summary: Various types of metallic nanoparticles and especially gold nanoparticles (AuNPs) have been utilized in radiation studies to enhance the radiosensitization of cancer cells while minimizing detrimental effects in normal tissue. The aim of our study was to investigate the biological responses of various human cancer cells to gold-nanoparticle-induced radiosensitization. This was accomplished by using different AuNPs and several techniques in order to provide valuable insights regarding the multiple adverse biological effects, following ionizing radiation (IR) in combination with AuNPs. Insightful methodologies such as transmission electron microscopy were employed to identify comprehensively the complexity of the biological damage occurrence. Our findings confirm that AuNP radiosensitization may occur due to extensive and/or complex DNA damage, cell death, or cellular senescence. This multiparameter study aims to further elucidate the biological mechanisms and at the same time provide new information regarding the use of AuNPs as radiosensitizers in cancer treatment. In the context of improving radiation therapy, high-atomic number (Z) metallic nanoparticles and, more importantly, gold-based nanostructures are developed as radiation enhancers/radiosensitizers. Due to the diversity of cell lines, nanoparticles, as well as radiation types or doses, the resulting biological effects may differ and remain obscure. In this multiparameter study, we aim to shed light on these effects and investigate them further by employing X-irradiation and three human cancer cell lines (PC3, A549, and U2OS cells) treated by multiple techniques. TEM experiments on PC3 cells showed that citrate-capped AuNPs were found to be located mostly in membranous structures/vesicles or autophagosomes, but also, in the case of PEG-capped AuNPs, inside the nucleus as well. The colony-forming capability of cancer cells radiosensitized by AuNPs decreased significantly and the DNA damage detected by cytogenetics, γH2AX immunostaining, and by single (γH2AX) or double (γH2AX and OGG1) immunolocalization via transmission electron microscopy (TEM) was in many cases higher and/or persistent after combination with AuNPs than upon individual exposure to ionizing radiation (IR). Moreover, different cell cycle distribution was evident in PC3 but not A549 cells after treatment with AuNPs and/or irradiation. Finally, cellular senescence was investigated by using a newly established staining procedure for lipofuscin, based on a Sudan Black-B analogue (GL13) which showed that based on the AuNPs' concentration, an increased number of senescent cells might be observed after exposure to IR. Even though different cell lines or different types and concentrations of AuNPs may alter the levels of radiosensitization, our results imply that the complexity of damage might also be an important factor of AuNP-induced radiosensitization. [ABSTRACT FROM AUTHOR]

Graphene/metal nanocomposites have shown a strong potential for use in electronic applications. In particular, the combination of silver nanowires (AgNWs) with graphene derivatives leads to the formation of an efficient conductive network, thus improving the electrical properties of a composite. This work focused on developing highly conductive hydrophilic hybrids of simultaneously functionalized and reduced graphene oxide (f-rGO) and AgNWs in different weight ratios by following two different synthetic routes: (a) the physical mixture of f-rGO and AgNWs, and (b) the in situ reduction of GO in the presence of AgNWs. In addition, the role of AgNWs in improving the electrical properties of graphene derivatives was further examined by mixing AgNWs with a hybrid of few-layered graphene with functionalized multiwalled carbon nanotubes (FLG/MWNT-f-OH). The studied materials showed a remarkable improvement in the overall electrical conductivity due to the synergistic effect of their components, which was proportional to the percentage of Ag and dependent on the procedure of the hybrid formation. One of the f-rGO/AgNWs composites was also selected for the preparation of gravure printing inks that were tested to determine their rheological and printing properties. All of the f-rGO/AgNWs composites were shown to be very promising materials for use as conductive inks for flexible electronics. [ABSTRACT FROM AUTHOR]

In this work, the development of a novel sulfur-doped graphene aerogel composite reinforced with carbon fibers (CFs) is presented. Sulfur is entrapped between the graphene nanosheets when GO in the presence of sodium sulfide is reduced hydrothermally to rGO forming a stable hydrogel and an aerogel after freeze-drying. The simultaneous incorporation of CFs improves the mechanical stability of the final composite. The as-prepared composite combines the characteristics of graphene aerogels such as porosity, surface area, chemical inertness with the mechanical properties of CFs and the ability of sulfur to capture lithium, thus providing a material with promising electrochemical properties for lithium-ion battery applications. [ABSTRACT FROM AUTHOR]

Graphene aerogel (GA) is a lightweight, porous, environmentally friendly, 3D structured material with interesting properties, such as electrical conductivity, a high surface area, and chemical stability, which make it a powerful tool in energy storage, sensing, catalyst support, or environmental applications. However, the poor mechanical stability that often characterizes graphene aerogels is a serious obstacle for their use in such applications. Therefore, we report here the successful mechanical reinforcement of GA with carbon fibers (CFs) by combining reduced graphene oxide (rGO) and CFs in a composite material. The surfaces of the CFs were first successfully desized and enriched with epoxy groups using epichloridrine. Epoxy-functionalized CFs (epoxy-CFs) were further covered by reduced graphene oxide (rGO) nanosheets, using triethylene tetramine (TETA) as a linker. The rGO-covered CFs were finally incorporated into the GA, affording a stiff monolithic aerogel composite. The as-prepared epoxy-CF-reinforced GA was characterized by spectroscopic and microscopic techniques and showed enhanced electrical conductivity and compressive strength. The improved electrical and mechanical properties of the GA-CFs composite could be used, among other things, as electrode material or strain sensor applications. [ABSTRACT FROM AUTHOR]

Abstract Reduction of graphene oxide (GO) to a low-resistance product is one of the most versatile routes to obtain large volume graphene-based materials. A number of chemical and thermal methods are being applied to achieve this goal, albeit each one is bound to certain disadvantages and limitations. Laser-assisted reduction has emerged as a promising method apt to overcome issues related to chemical and thermal reduction. Despite that a large number of efforts have been focused on laser-induced reduction of GO, its transformation to high quality reduced GO still remains a bottleneck. Here, it is shown that low-cost, millisecond lasers, widely used in the welding industry, achieve excellent reduction of GO to a product with the lowest sheet resistance yet reported by any laser-assisted method. For comparison, GO is reduced by chemical and thermal methods. Raman and x-ray photoelectron spectroscopies are applied to investigate the underlying structural changes providing evidence for the removal of oxygen-containing species and defect healing. Operation at ambient conditions, single pulse irradiation and a 2.60 mm wide focusing spot, demonstrate the high potential of this approach to the scalability of the reduction process towards producing large volumes of high-quality reduced graphene oxide at low cost. Graphical abstract Image 1 [ABSTRACT FROM AUTHOR]

In this article, we describe the one-side functionalization of graphene nanosheets with hydrophilic catechol-bearing pyrrolidine rings. For this purpose, we used, for the first time, a solvothermal alternative of 1,3 dipolar cycloaddition of azomethine ylide. To achieve asymmetrical reaction, graphene nanosheets were initially and during reaction deposited on glass substrate. The result of one-side functionalization of graphene was the formation of amphiphilic few-layered graphene nanosheets. The modified side becomes hydrophilic due to the attachment of catechols, while the nonmodified side remains hydrophobic. In the literature, there are limited examples of functionalized graphene with different sides, the so-called Janus-type graphenes. These amphiphilic graphene nanosheets dispersed in water were self-organized in bilayer superstructures, with hydrophilic outer surface and hydrophobic internal space. The later can host hydrophobic molecules such as anticancer drugs and could be used in drug delivery systems. As an example, camptothecin, a drug practically insoluble in water, was used here to show that it can be transferred to water phase using graphene as transporter. [ABSTRACT FROM AUTHOR]

FePt nanoparticles with the chemically ordered fct crystal structure have been widely studied because of the unique magnetic properties and the electrocatalytic activity for Oxygen Reduction Reactions (ORR). In this study, reduced graphene oxide (r-GO) supported FePt nanoparticles are successfully synthesized by a facile and completely green chemical approach. The structural, morphological, physicochemical and magnetic properties of the synthesized materials are systematically investigated by X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM) measurements. It is shown that the FePt nanoparticles with the fct crystal structure uniformly growth on the surface of the r-GO and remain isolated even after high temperature thermal treatment. Furthermore, the nanocomposite materials reveal strong ferromagnetic behavior at room temperature. [ABSTRACT FROM AUTHOR]

The dual use of potassium superoxide (KO2) to unzip multiwalled carbon nanotubes (MWCNTs) and cut graphene under hydrothermal conditions is described in this work. The KO2-assisted hydrothermal treatment was proven to be a high-yield method for forming graphene nanoribbons and dots or sub-micro-sized graphene nanosheets. Starting with functionalized MWCNTs, the method produces water-dispersible graphene nanoribbons with characteristic photoluminescence depending on their width. Using pristine graphene, the hydrothermal treatment with KO2 produces nanosized graphene sheets and graphene quantum dots with diameters of less than 10 nm. The latter showed a bright white photoluminescence. The effective hydrothermal unzipping of MWNTs and the cutting of large graphene nanosheets is a valuable top-down approach for the preparation of graphene nanoribbons and small nanographenes. Both products with limited dimensions have interesting applications in nanoelectronics and bionanotechnology. [ABSTRACT FROM AUTHOR]

Abstract: In this work, we report on the interaction of a tyrosinate radical with single wall carbon nanotubes (CNT). The tyrosinate radical was formed from tyrosine (ester) by Fenton’s reagent and, reacted in situ with carbon nanotubes resulting in novel tyrosinated carbon nanotube derivatives. The covalent attachment of tyrosine on the external surface of the CNTs resulted in the appearance of a free radical, localized in the graphitic surface. The ‘electron injection’ (delocalization) of the free radical from the tyrosine ring onto the carbon nanotubes was studied and characterized by a combination of electron paramagnetic resonance, Raman and X-ray photoelectron spectroscopies, thermogravimetric analysis, as well as transmission electron and atomic force microscopies. The experiments, complemented by computer simulations, give insight into the formation process and structural details of the produced hybrid structures. [Copyright &y& Elsevier]

A letter is presented on the synthesis of carbon nanosheets via the solid-state pyrolysis of betaine.

In this paper, the absorption and fluorescence spectra of xanthene, 9-trimethylsilyl xanthene (1) and 9-methyl-9-trimethylsilyl xanthene (2) are presented and discussed with the help of CNDO/S and ab initio calculations. Introduction of the trimethylsilyl group at the 9-position of the xanthene molecule considerably shifts the short-wavelength band (246 nm) to the red and reduces the fluorescence quantum yields (Φfl = 0.03 for xanthene, 0.008 for 1 and <10−4 for 2 in MeCN) and the fluorescence lifetimes (τfl = 7.4 ns for xanthene, 220 ps for 1 and <100 ps for 2 in MeCN), while it does not affect seriously the long-wavelength band and the singlet excited state energies (ES = 97.7 kcal/mol for xanthene, 94.5 kcal/mol for 1 and 97.4 kcal/mol for 2 in MeCN). Ab initio calculations predict a ‘roof-like’ structure for 1 with folding angles 30° for the S0 and 20° for the S1 state. Laser (248, 266 and 308 nm) and lamp photolysis (254 nm) of 1 and 2 (MeCN or cyclohexane) results in [1,3]-trimethylsilyl rearrangement into the ortho-position of the xanthene moiety in the sense of a photo-Fries type reaction. The corresponding photo-Fries intermediates (exocyclic cyclohexatrienes: trimethyl-(1H-xanthen-1-yl)-silane, 1CHT and trimethyl-(9-methyl-1H-xanthen-1-yl)-silane, 2CHT) are formed within the 20 ns laser pulse and show absorption spectra peaking up at 410 and 403 nm, respectively. Additionally, small amounts of the corresponding 9-xanthyl radicals were detected as a result of the C-Si bond rupture. Using ps-laser flash photolysis (266 nm laser, MeCN) we observed a broad absorption spectrum peaking up at 960 nm and decaying monoexponentially with a lifetime of 130 ps, close to the measured fluorescence lifetime. We assigned therefore this transient to the singlet excited state of 1 (S1 → Sn absorption). We assume the S1 state as the origin of the photo-Fries rearrangement, giving via C-Si bond dissociation a singlet geminal radical pair (9-xanthyl radical + SiMe3). In the next step, the radical pair undergoes predominantly in-cage recombination to the persistent photo-Fries intermediates with high quantum yields (Φ1CHT = 0.70 and Φ2CHT = 0.50), while to a lesser extent it escapes the solvent cage (Φ = 0.30 for 1) and undergoes typical free radical reactions (e.g., scavenging with O2). The estimation of the above quantum yields was possible only after determination of the absorption coefficients (ɛ) of the photo-Fries intermediates [ɛ1CHT(410 nm) = 16,800 M−1 cm−1 and ɛ2CHT(403 nm) = 15,900 M−1 cm−1] using three independent methods; this represents the first example in the literature. [Copyright &y& Elsevier]