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2018|Action number: CA15107

EDITORIAL: Advances in nanocarbon composite materials

Author(s): Sharali Malik, Arkady V. Krasheninnikov, and Silvia Marchesan

Publisher(s): Beilstein Journal of Nanotechnology

ISBN/ISSN/DOI: doi:10.3762/bjnano.9.3

Beilstein-Journals

Materials have always been crucial to human development, to the point of being used as a reference to name specific stages of development. The first was the Stone Age, then the Bronze Age and then the Iron Age and on to their equivalents in modern times viz. the Plastic Age, the Silicon Age and the Nanomaterials Age. About 70% of all technical innovations (as estimated by the German federal government) can be attributed either directly or indirectly to the properties of the materials used – solutions are being explored on how to interface nanomaterials with other components in the macroscopic world. Therefore, we could reasonably state that we are entering the Composite Age. In particular, nanocarbons display unique properties to innovate in practically all technological sectors and branches of industry. This cutting-edge use of nano-augmented composite materials has the potential to reduce environmental pollution, to conserve resources, to save energy, and generally, to improve the quality of our lives.

2019|Action number: CA15107

Hard carbon derived from rice husk as low cost negative electrodes in Na-ion batteries

Author(s): Maria K. Rybarczyk, Yunming Li, Mo Qiao, Yong-Sheng Hu, Maria-Magdalena Titirici, and Marek Lieder

Publisher(s): Journal of Energy Chemistry

ISBN/ISSN/DOI: doi.org/10.1016/j.jechem.2018.01.025

Science Direct

Here, we report the synthesis of hard carbon materials (RH) made from natural rice husk through a single pyrolysis process and their application as an anode in sodium-ion batteries. The studies show that the electrochemical properties of RHs are affected by the treatment temperatures, which determine the materials morphology, in particular, their degree of graphitization and extent of continuous channels (nanovoids). The latter are accessible to sodium ions and significantly contribute to charge storage capacity of the produced anodes. The RHs obtained at 1600 °C deliver the highest reversible capacity of 276 mAh g−1 mainly due to insertion of sodium ions into the nanovoids. This work deepens the basic understanding of the influence of the carbonization temperature on the sodium storage mechanism.

2018|Action number: CA15107

Nanotubes from Atlantis: Magnetite in pumice as a catalyst for the growth of carbon nanotubes

Author(s): Sharali Malik

Publisher(s): Polyhedron

ISBN/ISSN/DOI: doi:10.1016/j.poly.2018.06.033

Science Direct

Nanosized carbon materials such as carbon nanotubes (CNTs) provide the possibility to achieve, in terms of tensile strength and Young’s modulus, incredibly strong materials. Therefore, the fabrication of nanocomposites with CNTs offers the potential for applications in electronics, medicine, defense and aerospace. Furthermore, it has been shown that having branched CNT structures is a promising way forward in terms of providing structures with enhanced mechanical properties. However, in order to realize this, mass production techniques at reasonable costs are needed. One possibility is the chemical vapor deposition (CVD) method which involves the decomposition of a hydrocarbon e.g. benzene, ethylene, methane, etc. over catalytically active metal deposited on or inside a support such as silica, alumina or titania. Here we report a simple and industrially scalable CVD process to manufacture long single-walled carbon nanotubes (SWNTs), branched multi-walled carbon nanotubes (b-MWNTs) and multi-walled carbon nanotubes (MWNTs) using the abundant pumice from the Akrotiri volcanoes on the Greek island of Santorini to catalyze the transformation of the carbon in methane (CH4) into CNT materials.

2018|Action number: CA15107

Supercapacitors based on AC/MnO2 deposited onto dip-coated carbon nanofiber cotton fabric electrodes

Author(s): A.J. Paleo, P. Staiti, A. Brigandì, F.N. Ferreira, A.M.Rocha, F. Lufrano

Publisher(s): Energy Storage Materials

ISBN/ISSN/DOI: doi:10.1016/j.ensm.2017.12.013

Science Direct

This work introduces the preparation of flexible carbon composite electrodes based on the top-down approach starting from the dip-coating of carbon nanofibers (CNFs) onto a cotton fabric. On these so-obtained conductive cotton fabrics, further layers of activated carbon and manganese oxide (MnO2) materials were subsequently added to enhance the electrochemical performances of negative and positive electrodes. At the end, two different types of asymmetric supercapacitors (SCs) were assembled with those textile electrodes by using porous paper and Nafion-Na ion-exchange membranes as separators. The different SCs were electrochemically characterized by means of cyclic voltammetry (CV), galvanostatic charge/discharge (G–CD) and electrochemical impedance spectroscopy (EIS). These hybrid carbon-based textile SCs exhibited capacitance performance of 138 and 134 F g–1 with the porous paper and Nafion membrane, respectively, and low self-discharge rates. Furthermore, in this study is considered the combination of two methods (cycling and floating) for studying the long-term durability tests of SCs. In particular, the floating methodology utilizes much more harsh conditions than the common cycling based on G-CD tests at high currents usually discussed in literature. The solid-state (Nafion membrane) hybrid device demonstrated very long durability with 10 K cycles and additional 270 h at a constant voltage of 1.6 V. In summary, the hybrid SCs fabricated with low cost materials and simple methodologies reported in this study showed very promising results for flexible energy storage applications.

2018|Action number: CA15107

Graphene assisted template based LiMn2O4 flexible cathode electrodes

Author(s): Aslihan Guler, Seyma Ozcan Duman, Deniz Nalci, Mustafa Guzeler, Emrah Bulu,t Mehmet Oguz Guler, Hatem Akbulut

Publisher(s): International Journal of Energy Research

ISBN/ISSN/DOI: doi:10.1002/er.4043

Wiley Online Library

In this paper, a systematic method has been developed to produce highly flexible and robust graphene/LiMn2O4 (G/LMO) and graphene/LiCr0.05Mn1.95O4 (G/LCMO) free‐standing composite cathode electrodes with increased specific capacity and improved electrochemical capability. Spinel LMO nanorods are synthesized by calcination method followed by a hydrothermal reaction technique. As‐synthesized nanorods were then embedded in a graphene layer which will in turn serve as a self‐standing binder‐free cathode electrode. Spinel LMO and LCMO nanorods with a length of 600 nm and width of 50 nm were then homogenously entrapped and distributed within the layers of conductive graphene structure. This hybrid structure will help to eliminate the use of heavy metal current collectors and electrically resistant binders or even conductive additives. A discharge capacity of 114.5 mAh g−1 is obtained after first cycle and %72 capacity retention is obtained after 250 cycles from G/LCMO freestanding samples. The enhancement in the electrochemical properties is due to the unique freestanding structure of the cathode electrodes.

2018|Action number: CA15107

Graphene composites with dental and biomedical applicability

Author(s): Sharali Malik, Felicite M. Ruddock, Adam H. Dowling, Kevin Byrne, Wolfgang Schmitt, Ivan Khalakhan, Yoshihiro Nemoto, Hongxuan Guo, Lok Kumar Shrestha, Katsuhiko Ariga, and Jonathan P. Hill

Publisher(s): Beilstein Journal of Nanotechnology

ISBN/ISSN/DOI: doi:10.3762/bjnano.9.73

Beilstein-Journals

Pure graphene in the form of few-layer graphene (FLG) – 1 to 6 layers – is biocompatible and non-cytotoxic. This makes FLG an ideal material to incorporate into dental polymers to increase their strength and durability. It is well known that graphene has high mechanical strength and has been shown to enhance the mechanical, physical and chemical properties of biomaterials. However, for commercial applicability, methods to produce larger than lab-scale quantities of graphene are required. Here, we present a simple method to make large quantities of FLG starting with commercially available multi-layer graphene (MLG). This FLG material was then used to fabricate graphene dental-polymer composites. The resultant graphene-modified composites show that low concentrations of graphene (ca. 0.2 wt %) lead to enhanced performance improvement in physio-mechanical properties – the mean compressive strength increased by 27% and the mean compressive modulus increased by 22%. Herein we report a new, cheap and simple method to make large quantities of few-layer graphene which was then incorporated into a common dental polymer to fabricate graphene-composites which shows very promising mechanical properties.

2018|Action number: CA15107

Absolute determination of optical constants of three transition metals using reflection electron energy loss spectroscopy

Author(s): H. Xu, L. H. Yang, J. Tóth, K. Tőkési, B. Da, and Z. J. Ding

Publisher(s): Journal of Applied Physics

ISBN/ISSN/DOI: doi:10.1063/1.5012013

AIP Scitation

The optical constants, n and k, of three transition metals (Cr, Co, and Pd) were determined from the measured reflection electron energy-loss spectroscopy (REELS) spectra, covering the spectral energy range from visible to vacuum ultraviolet. To do this, a spectral data analysis technique [Xu et al., Phys. Rev. B 95, 195417 (2017)], which combines a sophisticated Monte Carlo simulation for modelling the experimental REELS spectrum and the simulated annealing algorithm for the determination of the true energy loss function (ELF) was adopted. The validity of the obtained ELFs was discussed by comparing with the previous data derived by optical methods and by applying the oscillator strength and the perfect screening-sum rules. Besides, the consistency of the calculated data was evaluated for three in situ measurements for each sample at three primary energies. The complex dielectric function, the refractive index n and the extinction coefficient k were then derived from the obtained ELF via the analytical Kramers-Kronig relation.

2018|Action number: CA15107

Gas-Phase Functionalization of Macroscopic Carbon Nanotube Fiber Assemblies: Reaction Control, Electrochemical Properties, and Use for Flexible Supercapacitors

Author(s): Daniel Iglesias, Evgeny Senokos, Belén Alemán, Laura Cabana, Cristina Navío, Rebeca Marcilla, Maurizio Prato, Juan J. Vilatela, and Silvia Marchesan

Publisher(s): ACS Applied Materials and Interfaces

ISBN/ISSN/DOI: doi:10.1021/acsami.7b15973

ACS Publications

The assembly of aligned carbon nanotubes (CNTs) into fibers (CNTFs) is a convenient approach to exploit and apply the unique physico–chemical properties of CNTs in many fields. CNT functionalization has been extensively used for its implementation into composites and devices. However, CNTF functionalization is still in its infancy because of the challenges associated with preservation of CNTF morphology. Here, we report a thorough study of the gas-phase functionalization of CNTF assemblies using ozone which was generated in situ from a UV source. In contrast with liquid-based oxidation methods, this gas-phase approach preserves CNTF morphology, while notably increasing its hydrophilicity. The functionalized material is thoroughly characterized by Raman spectroscopy, X-ray photoelectron spectroscopy, transmission electron microscopy, and scanning electron microscopy. Its newly acquired hydrophilicity enables CNTF electrochemical characterization in aqueous media, which was not possible for the pristine material. Through comparison of electrochemical measurements in aqueous electrolytes and ionic liquids, we decouple the effects of functionalization on pseudocapacitive reactions and quantum capacitance. The functionalized CNTF assembly is successfully used as an active material and a current collector in all-solid supercapacitor flexible devices with an ionic liquid-based polymer electrolyte.

2017|Action number: CA15107

Synthesis of Nitrogen Doped Single Walled Carbon Nanotubes With Caffeine

Author(s): Filippo Fedi, Oleg Domanov, Paola Ayala, Thomas Pichler

Publisher(s): Physica Status Solidi B

ISBN/ISSN/DOI: doi:10.1002/pssb.201700364

Wiley Online Library

Nitrogen doped single walled carbon nanotubes have many functional benefits. Doping opens the possibility to control the electronic energy levels, surface energy, surface reactivity, and charge carrier density. The additional electron in the outer shell changes the electronic properties of the nanotubes when introduced into the carbon lattice. Here we present the latest findings in the in situ doping during synthesis of single walled carbon nanotubes using caffeine as a precursor of both carbon and nitrogen. A special furnace with two heating elements allowed us to sublimate and decompose the solid precursor. Caffeine allowed us to reach a high doping percentage with high quality nanotubes directly in a one‐step synthesis procedure.

2017|Action number: CA15107

Electrospun carbon nanofiber web electrode: Supercapacitor behavior in various electrolytes

Author(s): Ezgi Ismar, Tolga Karazehir, Murat Ates, A. Sezai Sarac

Publisher(s): The Journal of Applied Polymer Science

ISBN/ISSN/DOI: doi:10.1002/app.45723

Wiley Online Library

Carbon nanofibers (CNFs) draw great interest due to their noticeable mechanical, electrochemical, and physical properties. In this study, polyacrylonitrile‐based CNFs are obtained via electrospinning technique. Thermal oxidation and low temperature (950 °C) carbonization are applied to the electrospun web in order to achieve CNF. Through the process, Fourier transform infrared‐attenuated total reflectance spectroscopy and Raman spectroscopic results are investigated. The electrochemical properties of the self‐standing CNF webs are examined with electrochemical impedance spectroscopy and cyclic voltammetry. In addition, various electrolyte solutions are studied to investigate the capacitive behavior of CNF webs. Electrolyte type variation has a significant effect on the capacitance results and high capacitance values are achieved in aqueous solution. According to the differing electrolyte types, specific capacitance values (Csp) are recorded between 204 and 149 F g−1 where maximum specific capacitance is obtained in 0.5 M H2SO4 as 204 F g−1

2017|Action number: CA15107

A Molecular Pillar Approach To Grow Vertical Covalent Organic Framework Nanosheets on Graphene: Hybrid Materials for Energy Storage

Author(s): Jinhua Sun, Alexey Klechikov, Calin Moise, Mariana Prodana, Marius Enachescu, Alexandr V. Talyzin

Publisher(s): Angewandte Chemie

ISBN/ISSN/DOI: doi:10.1002/anie.201710502

Wiley Online Library

Hybrid 2D–2D materials composed of perpendicularly oriented covalent organic frameworks (COFs) and graphene were prepared and tested for energy storage applications. Diboronic acid molecules covalently attached to graphene oxide (GO) were used as nucleation sites for directing vertical growth of COF‐1 nanosheets (v‐COF‐GO). The hybrid material has a forest of COF‐1 nanosheets with a thickness of 3 to 15 nm in edge‐on orientation relative to GO. The reaction performed without molecular pillars resulted in uncontrollable growth of thick COF‐1 platelets parallel to the surface of GO. The v‐COF‐GO was converted into a conductive carbon material preserving the nanostructure of precursor with ultrathin porous carbon nanosheets grafted to graphene in edge‐on orientation. It was demonstrated as a high‐performance electrode material for supercapacitors. The molecular pillar approach can be used for preparation of many other 2D‐2D materials with control of their relative orientation.

2017|Action number: CA15107

Carbon nano-onions in biomedical applications: Promising theranostic agents

Author(s): Adalberto Camisasca, Silvia Giordani

Publisher(s): Inorganica Chimica Acta

ISBN/ISSN/DOI: doi:10.1016/j.ica.2017.06.009

Science Direct

Carbon nano-onions (CNOs) are an emerging class of nanoparticles which shows great potential in a number of different applications. Carbon nano-materials have been widely explored in biological cell imaging, due to their lack of toxicity, and biosafety. Recently, the rapid development and availability of chemical surface modification methods have made it possible to explore these cage-in-cage structured nanoparticles as novel systems for biological applications. The functionalization of CNOs with different functional groups improves their solubility and biocompatibility, resulting in an increased ability to penetrate into the cells. Moreover, their small size and high surface area allow for the conjugation of different diagnostic and therapeutic agents, opening new avenues in theranostic applications. In this review article, we discuss the latest advances reported by our group regarding the use of CNOs for biomedical applications and our findings confirm their great potentiality as promising platform for novel therapeutic approaches.

2017|Action number: CA15107

Recent advances in smart biotechnology: Hydrogels and nanocarriers for tailored bioactive molecules depot

Author(s): Gesmi Milcovich, Stefania Lettieri, Filipe E. Antunes, Bruno Medronho, Ana C. Fonseca, Jorge F.J. Coelho, Paolo Marizza, Francesca Perrone, Rossella Farra, Barbara Dapas, Gabriele Grassi, Mario Grassi, Silvia Giordani

Publisher(s): Advances in Colloid and Interface Science

ISBN/ISSN/DOI: doi:10.1016/j.cis.2017.05.009

Science Direct

Over the past ten years, the global biopharmaceutical market has remarkably grown, with ten over the top twenty worldwide high performance medical treatment sales being biologics. Thus, biotech R&D (research and development) sector is becoming a key leading branch, with expanding revenues. Biotechnology offers considerable advantages compared to traditional therapeutic approaches, such as reducing side effects, specific treatments, higher patient compliance and therefore more effective treatments leading to lower healthcare costs. Within this sector, smart nanotechnology and colloidal self-assembling systems represent pivotal tools able to modulate the delivery of therapeutics. A comprehensive understanding of the processes involved in the self-assembly of the colloidal structures discussed therein is essential for the development of relevant biomedical applications.In this review we report the most promising and best performing platforms for specific classes of bioactive molecules and related target, spanning from siRNAs, gene/plasmids, proteins/growth factors, small synthetic therapeutics and bioimaging probes.

2017|Action number: CA15107

Miniemulsion copolymerization of (meth)acrylates in the presence of functionalized multiwalled carbon nanotubes for reinforced coating applications

Author(s): Bertha T. Pérez-Martínez, Lorena Farías-Cepeda, Víctor M. Ovando-Medina, José M. Asua, Lucero Rosales-Marines, and Radmila Tomovska

Publisher(s): Beilstein Journal of Nanotechnology

ISBN/ISSN/DOI: doi:10.3762/bjnano.8.134

Beilstein-Journals

Film forming, stable hybrid latexes made of methyl metacrylate (MMA), butyl acrylate (BA) and 2-hydroxyethyl methacrylate (HEMA) copolymer reinforced with modified multiwalled carbon nanotubes (MWCNTs) were synthesized by in situ miniemulsion polymerization. The MWCNTs were pretreated by an air sonication process and stabilized by polyvinylpyrrolidone. The presence of the MWCNTs had no significant effect on the polymerization kinetics, but strongly affected the polymer characteristics (Tg and insoluble polymer fraction). The performance of the in situ composites was compared with that of the neat polymer dispersion as well as with those of the polymer/MWCNT physical blends. The in situ composites showed the presence of an additional phase likely due to the strong interaction between the polymer and MWNCTs (including grafting) that reduced the mobility of the polymer chains. As a result, a substantial increase of both the storage and the loss moduli was achieved. At 60 °C, which is above the main transition region of the polymer, the in situ composites maintained the reinforcement, whereas the blends behaved as a liquid-like material. This suggests the formation of a 3D network, in good agreement with the high content of insoluble polymer in the in situ composites.

2017|Action number: CA15107

Ab initio study of the electron energy loss function in a graphene-sapphire-graphene composite system

Author(s): Vito Despoja, Tijana Djordjević, Lazar Karbunar, Ivan Radović, and Zoran L. Mišković

Publisher(s): Physical Review B

ISBN/ISSN/DOI: doi:10.1103/PhysRevB.96.075433

APS Journals

The propagator of a dynamically screened Coulomb interaction W in a sandwichlike structure consisting of two graphene layers separated by a slab of Al2O3 (or vacuum) is derived from single-layer graphene response functions and by using a local dielectric function for the bulk Al2O3. The response function of graphene is obtained using two approaches within the random phase approximation (RPA): an ab initio method that includes all electronic bands in graphene and a computationally less demanding method based on the massless Dirac fermion (MDF) approximation for the low-energy excitations of electrons in the π bands. The propagator W is used to derive an expression for the effective dielectric function of our sandwich structure, which is relevant for the reflection electron energy loss spectroscopy of its surface. Focusing on the range of frequencies from THz to mid-infrared, special attention is paid to finding an accurate optical limit in the ab initio method, where the response function is expressed in terms of a frequency-dependent conductivity of graphene. It was shown that the optical limit suffices for describing hybridization between the Dirac plasmons in graphene layers and the Fuchs-Kliewer phonons in both surfaces of the Al2O3 slab, and that the spectra obtained from both the ab initio method and the MDF approximation in the optical limit agree perfectly well for wave numbers up to about 0.1 nm−1. Going beyond the optical limit, the agreement between the full ab initio method and the MDF approximation was found to extend to wave numbers up to about 0.3 nm−1 for doped graphene layers with the Fermi energy of 0.2 eV.

2017|Action number: CA15107

Porous graphite oxide pillared with tetrapod-shaped molecules

Author(s): Jinhua Sun, Francisco Morales-Lara, Alexey Klechikov, Alexandr V. Talyzin, Igor A. Baburin, Gotthard Seifert, Francesca Cardano, Michele Baldrighi, Marco Frasconi, Silvia Giordani

Publisher(s): Carbon

ISBN/ISSN/DOI: doi:10.1016/j.carbon.2017.05.007

Science Direct

Porous pillared graphene oxide (GO) materials were prepared using solvothermal reaction of Hummers GO with solution of Tetrakis(4-aminophenyl)methane (TKAm) in methanol. The intercalation of TKAm molecules between individual GO sheets, performed under swelling condition, results in expansion of inter-layer distance of GO from ∼7.5 Å to 13-14 Å. Pillaring GO with bulky, rigid 3D shaped TKAm molecules could be an advantage for the preparation of stable pillared structures compared to e.g. aliphatic or aromatic diamines. Insertion of TKAm molecules into inter-layer space of GO results in formation of interconnected network of sub-nanometer slit pores. The expanded GO structure prepared with optimized GO/TKAm composition shows Specific Surface Area (SSA) up to 660 m2/g which is among the highest reported for GO materials pillared using organic spacers. Modelling of GO structures pillared with TKAm molecules shows that maximal SSA of about 2300 m2/g is theoretically possible for realistic concentration of pillaring molecules in GO interlayers. Hydrogen sorption by pillared GO/TKAm is found to follow standard correlation with SSA both at ambient and liquid nitrogen temperatures with highest uptakes of 1.66 wt% achieved at 77 K and 0.25 wt% at 295 K. Our theoretical simulations show that pillared GO structures do not provide improvement of hydrogen storage beyond well-established physisorption trends even for idealized materials with subnanometer pores and SSA of 2300–3700 m2/g.

2017|Action number: CA15107

Toxicity Assessment of Carbon Nanomaterials in Zebrafish during Development

Author(s): Marta d’Amora, Adalberto Camisasca, Stefania Lettieri and Silvia Giordani

Publisher(s): Nanomaterials

ISBN/ISSN/DOI: doi:10.3390/nano7120414

MPDI

Carbon nanomaterials (CNMs) are increasingly employed in nanomedicine as carriers for intracellular transport of drugs, imaging probes, and therapeutics agents, thanks to their unique optical and physicochemical properties. However, a better understanding about the effects of CNMs on a vertebrate model at the whole animal level is required. In this study, we compare the toxicity of oxidized carbon nano-onions (oxi-CNOs), oxidized carbon nano-horns (oxi-CNHs) and graphene oxide (GO) in zebrafish (Danio rerio). We evaluate the possible effects of these nanomaterials on zebrafish development by assessing different end-points and exposure periods

2017|Action number: CA15107

Optimal nanomaterial concentration: harnessing percolation theory to enhance polymer nanocomposite performance

Author(s): Roey Nadiv, Michael Shtein, Gal Shachar, Maxim Varenik, and Oren Regev

Publisher(s): Nanotechnology

ISBN/ISSN/DOI: doi:10.1088/1361-6528/aa793e

IOPscience

A major challenge in nanocomposite research is to predict the optimal nanomaterial concentration (ONC) yielding a maximal reinforcement in a given property. We present a simple approach to identify the ONC based on our finding that it is typically located in close proximity to an abrupt increase in polymer matrix viscosity, termed the rheological percolation threshold, and thus may be used as an indicator of the ONC. This premise was validated by rheological and fractography studies of composites loaded by nanomaterials including graphene nanoribbons or carbon or tungsten disulfide nanotubes. The correlation between in situ viscosity, the rheological percolation threshold concentration and the nanocomposite fractography demonstrates the utility of the method.

2017|Action number: CA15107

Palladium Nanoparticles Decorated Graphene Oxide: Active and Reusable Nanocatalyst for the Catalytic Reduction of Hexavalent Chromium(VI)

Author(s): Dr. Metin Celebi, Kadir Karakas, Ilknur Efecan Ertas, Dr. Murat Kaya, Dr. Mehmet Zahmakiran

Publisher(s): Chemistry Select

ISBN/ISSN/DOI: doi:10.1002/slct.201700967

Wiley Online Library

Today, the catalytic reduction of Cr(VI) to Cr(III) stands one of the most important challenges in the environmental chemistry and catalysis due to highly stable, contaminant and toxic nature of Cr(VI). In this study, we show that a new nanocatalyst system comprised of 3‐aminopropyltriethoxysilane (APTS) stabilized palladium(0) nanoparticles grafted onto the surface of graphene oxide (Pd/GO) efficiently works in the catalytic reduction of Cr(VI) to Cr(III) under mild reaction conditions. Pd/GO nanocatalyst was reproducibly prepared through two‐steps procedure: (i) H2 reduction of Pd(dba)2 (dba=dibenzylideneacetone) in the presence of APTS in THF to synthesize colloidal APTS stabilized palladium(0) nanoparticles and then (ii) the deposition of 3‐aminopropyltriethoxysilane stabilized palladium(0) nanoparticles onto the surface of graphene oxide (GO) by impregnation. The characterization of Pd/GO was carried out by advanced analytical techniques. The summation of the results acquired from these analyses reveals that the formation of well‐dispersed and highly crystalline palladium(0) nanoparticles on the surface of GO. The catalytic performance of the resulting Pd/GO in terms of activity and stability was assessed in the catalytic reduction of Cr(VI) to Cr(III) in aqueous solution in the presence of formic acid (HCOOH) as a reducing agent. We found that Pd/GO nanocatalyst exhibits high activity (TOF=3.6 mol Cr2O72−/mol Pd×min) and reusability (> 90% at 5th reuse) in this catalytic transformation at room temperature.

2017|Action number: CA15107

Far-red fluorescent carbon nano-onions as a biocompatible platform for cellular imaging

Author(s): Stefania Lettieri, Adalberto Camisasca, Marta d'Amora, Alberto Diaspro, Takashi Uchida, Yoshikata Nakajima, Keiichi Yanagisawa, Toru Maekawa and Silvia Giordani

Publisher(s): RSC Advances

ISBN/ISSN/DOI: doi: 10.1039/C7RA09442F

RSC Publishing

A new generation of fluorescent carbon nano-onions with enhanced solubility in biological media and bright photoluminescence is reported. The nano-onions functionalized with a water soluble boron dipyrromethene dye emit in the far red spectrum with a high quantum yield (ΦF) and are suitable for high resolution imaging. The nanoparticles are characterized by a variety of different analytical techniques such as thermogravimetric analysis, dynamic light scattering, zeta potential, electron microscopy, Raman, X-ray photoelectron and fluorescence spectroscopies. They are easily internalized by human breast cancer cells (MCF-7) without any significant toxic effects. Moreover, confocal imaging studies show they exhibit a high fluorescence intensity and are localized in the lysosomes at a very low concentration. Our findings confirm the excellent potentialities of these functionalized carbon nanomaterials as biocompatible platform for high resolution biological imaging.

2017|Action number: CA15107

Luminescent supramolecular hydrogels from a tripeptide and nitrogen-doped carbon nanodots

Author(s): Maria C. Cringoli, Slavko Kralj, Marina Kurbasic, Massimo Urban, and Silvia Marchesan

Publisher(s): Beilstein Journal of Nanotechnology

ISBN/ISSN/DOI: doi:10.3762/bjnano.8.157

Beilstein-Journals

The combination of different components such as carbon nanostructures and organic gelators into composite nanostructured hydrogels is attracting wide interest for a variety of applications, including sensing and biomaterials. In particular, both supramolecular hydrogels that are formed from unprotected D,L-tripeptides bearing the Phe-Phe motif and nitrogen-doped carbon nanodots (NCNDs) are promising materials for biological use. In this work, they were combined to obtain luminescent, supramolecular hydrogels at physiological conditions. The self-assembly of a tripeptide upon application of a pH trigger was studied in the presence of NCNDs to evaluate effects at the supramolecular level. Luminescent hydrogels were obtained whereby NCND addition allowed the rheological properties to be fine-tuned and led to an overall more homogeneous system composed of thinner fibrils with narrower diameter distribution.

2017|Action number: CA15107

Oxidative stabilization of polyacrylonitrile nanofibers and carbon nanofibers containing graphene oxide (GO): a spectroscopic and electrochemical study

Author(s): İlknur Gergin, Ezgi Ismar, and A. Sezai Sarac

Publisher(s): Beilstein Journal of Nanotechnology

ISBN/ISSN/DOI: doi:10.3762/bjnano.8.161

Beilstein-Journals

In this study, a precursor for carbon nanofibers (CNF) was fabricated via electrospinning and carbonized through a thermal process. Before carbonization, oxidative stabilization should be applied, and the oxidation mechanism also plays an important role during carbonization. Thus, the understanding of the oxidation mechanism is an essential part of the production of CNF. The oxidation process of polyacrylonitrile was studied and nanofiber webs containing graphene oxide (GO) are obtained to improve the electrochemical properties of CNF. Structural and morphological characterizations of the webs are carried out by using attenuated total reflectance Fourier transform infrared spectroscopy and Raman spectroscopy, scanning electron microscopy, atomic force microscopy and transmission electron microscopy. Mechanical tests are performed with a dynamic mechanical analyzer, and thermal studies are conducted by using thermogravimetric analysis. Electrochemical impedance spectroscopy, and cyclic voltammetry are used to investigate capacitive behavior of the products. The proposed equivalent circuit model was consistent with charge-transfer processes taking place at interior pores filled with electrolyte.

2017|Action number: CA15107

Carbon nano-onions as fluorescent on/off modulated nanoprobes for diagnostics

Author(s): Stefania Lettieri, Marta d’Amora, Adalberto Camisasca, Alberto Diaspro, and Silvia Giordani

Publisher(s): Beilstein Journal of Nanotechnology

ISBN/ISSN/DOI: doi:10.3762/bjnano.8.188

Beilstein-Journals

Multishell fullerenes, known as carbon nano-onions (CNOs), have emerged as a platform for bioimaging because of their cell-penetration properties and minimal systemic toxicity. Here, we describe the covalent functionalization of CNOs with a π-extended distyryl-substituted boron dipyrromethene (BODIPY) dye with on/off modulated fluorescence emission activated by an acidic environment. The switching properties are linked to the photoinduced electron transfer (PET) characteristics of the dimethylamino functionalities attached to the BODIPY core. The on/off emission of the fluorescent CNOs is fast and reversible both in solution and in vitro, making this nanomaterial suitable as pH-dependent probes for diagnostic applications.

2017|Action number: CA15107

Enhancement of mechanical and electrical properties of continuous-fiber-reinforced epoxy composites with stacked graphene

Author(s): Naum Naveh, Olga Shepelev and Samuel Kenig

Publisher(s): Beilstein Journal of Nanotechnology

ISBN/ISSN/DOI: doi:10.3762/bjnano.8.191

Beilstein-Journals

Impregnation of expandable graphite (EG) after thermal treatment with an epoxy resin containing surface-active agents (SAAs) enhanced the intercalation of epoxy monomer between EG layers and led to further exfoliation of the graphite, resulting in stacks of few graphene layers, so-called “stacked” graphene (SG). This process enabled electrical conductivity of cured epoxy/SG composites at lower percolation thresholds, and improved thermo-mechanical properties were measured with either Kevlar, carbon or glass-fiber-reinforced composites. Several compositions with SAA-modified SG led to higher dynamic moduli especially at high temperatures, reflecting the better wetting ability of the modified nanoparticles. The hydrophilic/hydrophobic nature of the SAA dictates the surface energy balance. More hydrophilic SAAs promoted localization of the SG at the Kevlar/epoxy interface, and morphology seems to be driven by thermodynamics, rather than the kinetic effect of viscosity. This effect was less obvious with carbon or glass fibers, due to the lower surface energy of the carbon fibers or some incompatibility with the glass-fiber sizing. Proper choice of the surfactant and fine-tuning of the crosslink density at the interphase may provide further enhancements in thermo-mechanical behavior.

2017|Action number: CA15107

Freestanding graphene/MnO2 cathodes for Li-ion batteries

Author(s): Şeyma Özcan, Aslıhan Güler, Tugrul Cetinkaya, Mehmet O. Guler and Hatem Akbulut

Publisher(s): Beilstein Journal of Nanotechnology

ISBN/ISSN/DOI: doi:10.3762/bjnano.8.191

Beilstein-Journals

Different polymorphs of MnO2 (α-, β-, and γ-) were produced by microwave hydrothermal synthesis, and graphene oxide (GO) nanosheets were prepared by oxidation of graphite using a modified Hummers’ method. Freestanding graphene/MnO2 cathodes were manufactured through a vacuum filtration process. The structure of the graphene/MnO2 nanocomposites was characterized using X-ray diffraction (XRD) and Raman spectroscopy. The surface and cross-sectional morphologies of freestanding cathodes were investigated by scanning electron microcopy (SEM). The charge–discharge profile of the cathodes was tested between 1.5 V and 4.5 V at a constant current of 0.1 mA cm−2 using CR2016 coin cells. The initial specific capacity of graphene/α-, β-, and γ-MnO2 freestanding cathodes was found to be 321 mAhg−1, 198 mAhg−1, and 251 mAhg−1, respectively. Finally, the graphene/α-MnO2 cathode displayed the best cycling performance due to the low charge transfer resistance and higher electrochemical reaction behavior. Graphene/α-MnO2 freestanding cathodes exhibited a specific capacity of 229 mAhg−1 after 200 cycles with 72% capacity retention.

2017|Action number: CA15107

Fast low-temperature plasma reduction of monolayer graphene oxide at atmospheric pressure

Author(s): Michal Bodik, Anna Zahoranova, Matej Micusik, Nikola Bugarova, Zdenko Spitalsky, Maria Omastova, Eva Majkova, Matej Jergel and Peter Siffalovic

Publisher(s): Nanotechnology

ISBN/ISSN/DOI: doi:10.1088/1361-6528/aa60ef

IOPscience

We report on an ultrafast plasma-based graphene oxide reduction method superior to conventional vacuum thermal annealing and/or chemical reduction. The method is based on the effect of non-equilibrium atmospheric-pressure plasma generated by the diffuse coplanar surface barrier discharge in proximity of the graphene oxide layer. As the reduction time is in the order of seconds, the presented method is applicable to the large-scale production of reduced graphene oxide layers. The short reduction times are achieved by the high-volume power density of plasma, which is of the order of 100 W cm−3. Monolayers of graphene oxide on silicon substrate were prepared by a modified Langmuir-Schaefer method and the efficient and rapid reduction by methane and/or hydrogen plasma was demonstrated. The best results were obtained for the graphene oxide reduction in hydrogen plasma, as verified by x-ray photoelectron spectroscopy and Raman spectroscopy.

2017|Action number: CA15107

Advances and challenges in the field of plasma polymer nanoparticles

Author(s): Andrei Choukourov, Pavel Pleskunov, Daniil Nikitin, Valerii Titov, Artem Shelemin, Mykhailo Vaidulych, Anna Kuzminova, Pavel Solař, Jan Hanuš, Jaroslav Kousal, Ondřej Kylián, Danka Slavínská1, and Hynek Biederman

Publisher(s): Beilstein Journal of Nanotechnology

ISBN/ISSN/DOI: doi:10.3762/bjnano.8.200

Beilstein-Journals

This contribution reviews plasma polymer nanoparticles produced by gas aggregation cluster sources either via plasma polymerization of volatile monomers or via radio frequency (RF) magnetron sputtering of conventional polymers. The formation of hydrocarbon, fluorocarbon, silicon- and nitrogen-containing plasma polymer nanoparticles as well as core@shell nanoparticles based on plasma polymers is discussed with a focus on the development of novel nanostructured surfaces.

2017|Action number: CA15107

Nanocrystalline diamond protects Zr cladding surface against oxygen and hydrogen uptake: Nuclear fuel durability enhancement

Author(s): Jan Škarohlíd, Petr Ashcheulov, Radek Škoda, Andrew Taylor, Radim Čtvrtlík, Jan Tomáštík, František Fendrych, Jaromír Kopeček, Vladimír Cháb, Stanislav Cichoň, Petr Sajdl, Jan Macák, Peng Xu, Jonna M. Partezana, Jan Lorinčík, Jana Prehradná, Martin Stein

Publisher(s): Scientific Reports

ISBN/ISSN/DOI: doi:10.1038/s41598-017-06923-4

Nature Articles

In this work, we demonstrate and describe an effective method of protecting zirconium fuel cladding against oxygen and hydrogen uptake at both accident and working temperatures in water-cooled nuclear reactor environments. Zr alloy samples were coated with nanocrystalline diamond (NCD) layers of different thicknesses, grown in a microwave plasma chemical vapor deposition apparatus. In addition to showing that such an NCD layer prevents the Zr alloy from directly interacting with water, we show that carbon released from the NCD film enters the underlying Zr material and changes its properties, such that uptake of oxygen and hydrogen is significantly decreased. After 100–170 days of exposure to hot water at 360 °C, the oxidation of the NCD-coated Zr plates was typically decreased by 40%. Protective NCD layers may prolong the lifetime of nuclear cladding and consequently enhance nuclear fuel burnup. NCD may also serve as a passive element for nuclear safety. NCD-coated ZIRLO claddings have been selected as a candidate for Accident Tolerant Fuel in commercially operated reactors in 2020.

2017|Action number: CA15107

Preparation and characterization of polycarbonate/multiwalled carbon nanotube nanocomposites

Author(s): Claudio Larosa, Niranjan Patra, Marco Salerno, Lara Mikac, Remo Merijs Meri, and Mile Ivanda

Publisher(s): Beilstein Journal of Nanotechnology

ISBN/ISSN/DOI: doi:10.3762/bjnano.8.203

Beilstein-Journals

A polymer nanocomposite was produced by ultrasonic-assisted dispersion of multiwalled carbon nanotubes (MWCNTs) in a polycarbonate matrix using p-xylene and dichloromethane as the solvents. The filler loading was varied from 1 to 3 wt % in order to examine the effect of MWCNTs on the structure and properties of the composites. The nanocomposites were characterized by DSC, DTA, TGA, UV–vis, FTIR and Raman spectroscopy to evaluate the changes induced by the filler in the polymer matrix. UV–vis, FTIR and Raman spectroscopy measurements confirmed the presence of the dispersed phase in the composite films, while TGA and DSC analysis of the nanocomposites revealed enhanced thermal stability and decreased crystallinity, respectively, as compared to the neat polymer. The proposed composites can find application in a number of everyday products where polycarbonate is the base polymer.

2016|Action number: CA15107

Fabrication and characterization of branched carbon nanostructures

Author(s): Sharali Malik, Yoshihiro Nemoto, Hingxuan Guo, Katsuhiko Ariga and Jonathan P. Hill

Publisher(s): Beilstein Journal of Nanotechnology

ISBN/ISSN/DOI: doi:10.3762/bjnano.7.116

Beilstein-Journals

Carbon nanotubes (CNTs) have atomically smooth surfaces and tend not to form covalent bonds with composite matrix materials. Thus, it is the magnitude of the CNT/fiber interfacial strength that limits the amount of nanomechanical interlocking when using conventional CNTs to improve the structural behavior of composite materials through reinforcement. This arises from two wellknown, long standing problems in this research field: (a) inhomogeneous dispersion of the filler, which can lead to aggregation and (b) insufficient reinforcement arising from bonding interactions between the filler and the matrix. These dispersion and reinforcement issues could be addressed by using branched multiwalled carbon nanotubes (b-MWCNTs) as it is known that branched fibers can greatly enhance interfacial bonding and dispersability. Therefore, the use of b-MWCNTs would lead to improved mechanical performance and, in the case of conductive composites, improved electrical performance if the CNT filler was better dispersed and connected. This will provide major benefits to the existing commercial application of CNT-reinforced composites in electrostatic discharge materials (ESD): There would be also potential usage for energy conversion, e.g., in supercapacitors, solar cells and Li-ion batteries. However, the limited availability of b-MWCNTs has, to date, restricted their use in such technological applications. Herein, we report an inexpensive and simple method to fabricate large amounts of branched-MWCNTs, which opens the door to a multitude of possible applications.

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