Straightforward synthesis of conductive graphene/polymer nanocomposites from graphite oxide

The reduction of graphite oxide (GO) in the presence of reactive poly(methyl methacrylate) (PMMA), under mild biphasic conditions, directly affords graphene grafted with PMMA. The resulting nanocomposite shows excellent electrical conductivities resulting from the optimal dispersion and exfoliation of graphene in the polymer matrix.     

Influence of the graphite type on the synthesis of polypropylene/graphene nanocomposites

In this work, the synthesis of polypropylene (PP)/graphene nanosheet (GNS) nanocomposites by in situ polymerization using metallocene catalysts was studied. Initial reactions were performed using rac‐Et(Ind)₂ZrCl₂ and rac‐Me₂Si(Ind)₂ZrCl₂ catalysts to select the best one to obtain good molecular weight, thermal properties, and tacticity. Subsequently, PP nanocomposites with different loadings of GNS were obtained. GNS from two different sources [Graphite Nacional (GN) and Graphite Aldrich (GA)] have been used, and the differences between the obtained nanocomposites were evaluated. The GNS and nanocomposites were studied by scanning electronic microcopy, transmission electronic microcopy, and X‐ray diffraction. They showed that the GN nanosheets had lower crystal size and diameter than the GA nanosheets and dispersed better in the PP matrix. Differential scanning calorimetry analyses of both types of nanocomposites showed an increase in the crystallization temperature with increasing graphite loading. The polymeric materials were also characterized by GPC, thermogravimetric analysis, and ¹³C NMR. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Flame synthesis of few-layered graphene/graphite films

We report a fast (in 10-40 s) flame synthesis of high quality few-layered graphene/graphite films, offering the advantages of simplicity, high efficiency, energy saving, low cost and the ability to extend to continuous and mass production of graphene.     

Facile synthesis of highly conductive polyaniline/graphite nanocomposites

A facile process for the synthesis of exfoliated graphite and polyaniline/graphite (PANI/graphite) nanocomposite was developed. Graphite nanosheets were prepared via the microwave irradiation and sonication from synthesized expandable graphite. The nanocomposites were fabricated via in situ polymerization of aniline monomer in the presence of graphite nanosheets. The nanoscale dispersion of graphite sheets was evidenced by the SEM and TEM examinations. According to the electrical conductivity test, the conductivity of the final PANI/graphite nanocomposites were dramatically increased compared with pristine PANI. From the thermogravimetric analysis, the introduction of graphite exhibits a beneficial effect on the thermal stability of PANI.     

Simulation and synthesis of graphene oxide from expanded graphite

Russian Journal of General Chemistry - Expanded graphite oxide and multilayered graphene oxide have been synthesized. The processes of thermal expansion of intercalated graphite and oxidation of...     

ATNRC/SET‐NRC synthesis of graphene/polyisobutylene nanocomposites

Two polyisobutylene‐grafted graphene nanocomposites were prepared by CuBr‐catalyzed atom transfer nitroxide radical coupling (ATNRC) and Cu‐catalyzed single electron transfer‐nitroxide radical coupling (SET‐NRC) chemistry under mild conditions, respectively, through the grafting‐onto strategy. Graphene oxide was first reduced to graphene by diazonium addition reaction followed by treating graphene with ethyl 2‐bromoisobutyrate for introducing Br‐containing groups onto the surface to give G‐Br. The presynthesized well‐defined functional polyisobutylene (PIB) possessing 2,2,6,6‐tetramethylpiperidine‐1‐oxyl terminal group obtained via cationic polymerization of isobutylene was then coupled with G‐Br through ATNRC or SET‐NRC at room temperature to afford polymer‐modified graphene, G‐PIB. SET‐NRC method has a faster coupling rate using cheaper reagent (Cu wire instead of CuBr) in comparison with ATNRC approach. Detailed characterizations including FT‐IR, Raman, ¹H NMR, TGA, AFM, and TEM assured us of successful anchoring of PIB chains onto the surface of graphene sheets. The resulting G‐PIB nanocomposites still maintain the separated single layers in dispersion and the dispersibilities in organic solvents are significantly improved. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013 , 51, 4505–4514     

Polymer/graphite nanocomposites: Effect of reducing the functional groups of graphite oxide on water barrier properties

Water barrier properties (i.e., water resistance) of poly(styrene-co-butyl acrylate)/graphite oxide (poly(St-co-BA)/GO) nanocomposites were studied using hydrophobicity and permeability analysis. Poly(St-co-BA)/GO nanocomposite latices were obtained using the miniemulsion polymerization technique. The hydrophobicity of the synthesized nanocomposites was studied using contact angle measurements, while water permeability was obtained by measuring the moisture vapor transmission rate (MVTR). The nanocomposites were treated with hydrazine hydrate in order to reduce the functional groups on graphite oxide (GO). The focus was on determining the effect of reducing the functional groups of GO on the water barrier properties of its polymer nanocomposites. In general, the nanolayered graphene platelets in GO and RGO resulted in lower water permeation in the final films compared to pure polymer. However, results showed that nanocomposites containing the reduced-GO (RGO) had better water resistance and barrier properties compared to those made with unreduced GO (i.e., as-prepared GO). The nanocomposites containing RGO had higher hydrophobicity and lower water uptake and MVTR compared to those made with as-prepared GO, resulting in better barrier performance. This was attributed to the high hydrophobic nature of the RGO, which exhibited lower water solubility that resulted in films with lower MVTR values compared to those made with as-prepared GO.     

Competitive surface-enhanced Raman scattering effects in noble metal nanoparticle-decorated graphene sheets

Herein, noble metal nanoparticle (Au or Ag NP) decorated graphene sheets, fabricated according to a facile one-pot environmentally friendly method, are used as good substrates for the investigation of the combined surface-enhanced Raman scattering (SERS) effect, where both the electromagnetic mechanism and the chemical mechanism effects coexist among the Au or Ag NPs, graphene sheets and the absorbed analytes. Our results show that, in aqueous solution, the SERS effect of both the Au and Ag NPs on the absorbed probe molecules and on graphene is competitive, which varies dependent on the species and the concentration of the absorbed probe molecule. By a detailed comparison of three probe molecules (rhodamine 6G, nile blue A, and 4-aminobenzenethiol) with different coupling abilities to the graphene sheets, we finally attribute this phenomenon to the result of the strong suppressing effect of the macrocyclic probe molecules on the SERS of graphene, induced by charge transfer, as the probe molecules are coupled to the graphene sheets. This competitive effect is a non-ignorable phenomenon when graphene/Au or Ag nanocomposites are used as SERS substrates, and our study may deepen our understanding of the SERS mechanism.     

高能量超声辅助制备负载型贵金属纳米催化材料

介绍了一种利用高能量超声作用制备负载型纳米催化材料的方法.通过高能量超声作用下发生的还原反应,使原位生成的贵金属或双金属纳米颗粒负载于各种载体的表面,制备了一系列石墨烯基-、碳纳米管基-、金属氧化物(二氧化铈、α-三氧化二铁、二氧化钛)基-负载型贵金属纳米催化材料,并利用光电子能谱、透射电子显微镜、元素分析、电子衍射等方法表征了材料的结构和形貌.结果表明:贵金属纳米颗粒在载体的表面均匀地分布,颗粒的尺寸较小,分布较窄;颗粒的尺寸可以通过金属在载体中的负载量、金属前驱体的浓度和超声强度容易地进行调控.这种方法为负载型贵金属纳米催化剂的制备提供了一种有效的途径.     

Microwave-assisted synthesis of BiOBr/graphene nanocomposites and their enhanced photocatalytic activity

BiOBr/graphene nanocomposites were synthesized by a green single-step microwave strategy and characterized by X-ray diffraction, field-emission scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy. The photocatalytic activity of the as-prepared BiOBr nanoplates and BiOBr/graphene nanocomposites for the photodegeneration of organic dyes in aqueous solution under visible light irradiation was investigated. The results show that BiOBr/graphene nanocomposites have a higher photocatalytic activity than bare BiOBr nanoplates.     

A review of transition metal chalcogenide/graphene nanocomposites for energy storage and conversion

Recent advances in the applications of transition metal chalcogenides/graphene (TMC/graphene) nanocomposites in future energy storage and conversion are reviewed. The synthesis processes and structures of TMC/graphene, workingpriciple of evergy energy device, and the electrochemical performances are summarized.     

Gemini surfactant assisted synthesis of two-dimensional metal nanoparticles/graphene composites

We demonstrate the synthesis of 2D metal nanoparticles (MNPs)/graphene nanocomposites using small cationic surfactants as stabilizers. 2D sandwich-like MNPs/graphene nanocomposites with a uniform distribution of MNPs can be achieved via a one-pot in situ growth and reduction protocol.     

Mixed colloidal suspensions of reduced graphene oxide and layered metal oxide nanosheets: useful precursors for the porous nanocomposites and hybrid films of graphene/metal oxide

Homogeneously mixed colloidal suspensions of reduced graphene oxide, or RGO, and layered manganate nanosheets have been synthesized by a simple addition of the exfoliated colloid of RGO into that of layered MnO(2). The obtained mixed colloidal suspensions with the RGO/MnO(2) ratio of ≤0.3 show good colloidal stability without any phase separation and a negatively charged state with a zeta (ζ) potential of -30 to -40?mV. The flocculation of these mixed colloidal suspensions with lithium cations yields porous nanocomposites of Li/RGO-layered MnO(2) with high electrochemical activity and a markedly expanded surface area of around 70-100?m(2) g(-1). Relative to the Li/RGO and Li/layered MnO(2) nanocomposites (≈116 and ≈167?F?g(-1)), the obtained Li/RGO-layered MnO(2) nanocomposites deliver a larger capacitance of approximately 210?F?g(-1) with good cyclability of around 95-97?% up to the 1000th cycle, thus indicating the positive effect of hybridization on the electrode performances of RGO and lithium manganate. Also, an electrophoretic deposition of the mixed colloidal suspensions makes it possible to easily fabricate uniform hybrid films composed of graphene and manganese oxide. The obtained films show a distinct electrochemical activity and a homogeneous distribution of RGO and MnO(2). The present experimental findings clearly demonstrate that the utilization of the mixed colloidal suspensions as precursors provides a facile and universal methodology to synthesize various types of graphene/metal oxide hybrid materials.     

贵金属杂化纳米材料的合成及性能研究进展

近年来,杂化纳米材料的出现极大地拓展了纳米材料的应用范围,其特殊的结构、性能、尺寸和形貌使其不仅保持了各组分材料的特性及功能,更涌现了不同于各组分材料所不具备的新颖的、多样化的特殊性能和应用潜能,因此其制备方法和性能应用已经成为了研究热点.运用纳米技术将贵金属纳米粒子与其他性能优异的物质结合形成的贵金属杂化纳米材料被广泛运用到电化学、光催化、免疫传感、生物催化和医药化学等领域.本文综述了贵金属杂化纳米材料的制备方法、结构组成、性能特点、应用前景以及最新的发展趋势,重点介绍了贵金属杂化纳米材料的合成及应用.     

A step forward in metal nitride and carbide synthesis: from pure nanopowders to nanocomposites

Transition metal nitrides and carbides (MN/MC) are intriguing materials due to their combination of properties that place them between high-performance ceramics and pure metals. Recent progress in easier synthetic routes toward their production as bulk or nanostructured materials explains the current surge in sustained attention such progress has been receiving. After progressing toward easier syntheses of MN/MC nanosystems as pure phases, coupling MN/MC with a second phase for the production of hybrids and nanocomposites is considered a next important step in the development of these nanosystems. The coupled phase can simply be a different nitride or carbide; it also can be a polymer, a poly(ionic liquid) or a carbon phase, just to give a few examples. The combination of these phases with MN/MC nanoparticles could lead to multifunctional materials. The aim of the present review is to show how far the research concerning the production of MN/MC-based nanocomposites has progressed, especially in terms of controlled composition, morphology and properties. We discuss the most intensely investigated systems and related motivations, as well as partially unexplored yet appealing alternative materials.     

In situ synthesis of crosslinked-polyaniline nano-pillar arrays/reduced graphene oxide nanocomposites for supercapacitors

Crosslinked-polyaniline (CPA) nano-pillar arrays adsorbed on the surface of reduced graphene oxide (RGO) sheets were synthesized by in situ solution polymerization through two steps of reduction. The electrochemical analyses demonstrated that the befittingly reduced CPA/RGO composite exhibited high performance as electrode materials for supercapacitors. The CPA/RGO composite showed very high specific capacitance of 1532 F g^?1 at a scan rate of 10 mV s^?1 or 694 F g^?1 at a current density of 2 A g^?1 in 1 M H₂SO₄ electrolyte, as well as great energy density of 61.4 W h kg^?1 at a current density of 2 A g^?1. The electrode material also had decent power density of 4 kW kg^?1 at a current density of 10 A g^?1, and good cycling stability of 92.5 % capacitance retained after 500 cycles of cyclic voltammetry at 500 mV s^?1. The neat microstructures and super electrochemical properties suggest the potential use of the composites in supercapacitors.     

Correlation between the electrification and molecular mobility of noble metal nanocomposites based on arabinogalactan

Spin-spin relaxation of arabinogalactan and its composites with gold and silver nanoparticles in aqueous solutions was studied from the viewpoint of the possible effect of electrification on the mobility of arabinogalactan macromolecules.     

Polyethylene/graphite nanocomposites obtained by in situ polymerization

The synthesis of polyethylene/graphite nanocomposites by in situ polymerization was achieved using the catalytic system Cp₂ZrCl₂ (bis(cyclopentadienyl)zirconium(IV) dichloride)/methylaluminoxane (MAO). Graphite with nano dimensions, previously treated with MAO, was added into the reactor as filler at percentages of 1, 2, and 5% (w/w). XRD analysis showed that the chemical and thermal treatments employed preserve the structure of the graphite sheets. The formation of graphite nanosheets and nanocomposites was confirmed by TEM and AFM. TEM micrographics showed that the polyethylene grew between the graphene nanosheets, giving intercalated and exfoliated graphite nanocomposites. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 692–698, 2010