Construction of TiO_(2)-pillared multilayer graphene nanocomposites as efficient photocatalysts for ciprofloxacin degradation

We successfully constructed TiO_(2)-pillared multilayer graphene nanocomposites(T-MLGs)via a facile method as follows:dodecanediamine pre-pillaring,ion exchange(Ti4+pillaring),and interlayer in-situ formation of TiO_(2) by hydrothermal method.TiO_(2) nanoparticles were distributed uniformly on the graphene interlayer.The special structure combined the advantages of graphene and TiO_(2) nanoparticles.As a result,T-MLGs with 64.3wt%TiO_(2) showed the optimum photodegradation rate and adsorption capabilities toward ciprofloxacin.The photodegradation rate of T-MLGs with 64.3wt%TiO_(2) was 78%under light-emitting diode light irradiation for 150 min.Meanwhile,the pseudofirst-order rate constant of T-MLGs with 64.3wt%TiO_(2) was 3.89 times than that of pristine TiO_(2).The composites also exhibited high stability and reusability after five consecutive photocatalytic tests.This work provides a facile method to synthesize semiconductor-pillared graphene nanocomposites by replacing TiO_(2) nanoparticles with other nanoparticles and a feasible means for sustainable utilization of photocatalysts in wastewater control.

Design of Fe(3–x)O4 raspberry decorated graphene nanocomposites with high performances in lithium-ion battery

Fe（3–x）O4 raspberry shaped nanostructures/graphene nanocomposites were synthesized by a one-step polyol-solvothermal method to be tested as electrode materials for Li-ion battery（LIB）. Indeed, Fe（3–x）O4 raspberry shaped nanostructures consist of original oriented aggregates of Fe（3–x）O4 magnetite nanocrystals, ensuring a low oxidation state of magnetite and a hollow and porous structure, which has been easily combined with graphene sheets. The resulting nanocomposite powder displays a very homogeneous spatial distribution of Fe（3–x）O4 nanostructures at the surface of the graphene sheets. These original nanostructures and their strong interaction with the graphene sheets resulted in very small capacity fading upon Li＋ion intercalation. Reversible capacity, as high as 660 m Ah/g, makes this material promising for anode in Li-ion batteries application.

Sandwich-type ordered mesoporous carbon/graphene nanocomposites derived from ionic liquid

Sandwich-type ordered mesoporous carbon/graphene nanocomposites were successfully synthesized using 2D ordered mesoporous silica/graphene nanocomposites as the hard template and an ionic liquid as a N-rich carbon source. We used an ionic liquid of 1-(3-cyanopropyl)-3-methylimidazolium dicyanamide containing nitrile groups (–CN) in the cation and anion as a carbon precursor for the preparation of the nanocomposites. Nitriles do not decompose under thermal treatment in an inert gas atmosphere, but leave significant amounts of N-rich carbon materials. The nanocomposites had a large surface area (1,316 m2·g–1), an average pore diameter of 5.9 nm, and high electrical conductivity. The nanocomposite electrode showed a high specific capacitance of 190 F·g–1at 0.5 A·g–1in 1 M TEABF4/AN electrolyte and a good rate capability between 0 and 2.7 V for supercapacitor (or ultracapacitor) applications. [Figure not available: see fulltext.] © 2016, Tsinghua University Press and Springer-Verlag Berlin Heidelberg.

Facile microwave approach towards high performance MoS2/graphene nanocomposite for hydrogen evolution reaction

Low-cost, highly efficient catalysts for hydrogen evolution reaction(HER) are very important to advance energy economy based on clean hydrogen gas. Intensive studies on two-dimensional molybdenum disulfides(2 D Mo S2) have been conducted due to their remarkable catalytic properties.However, most of the reported syntheses are time consuming,complicated and less efficient. The present work demonstrates the production of Mo S2/graphene catalyst via an ultra-fast(60 s) microwave-initiated approach. High specific surface area and conductivity of graphene delivers a favorable conductive network for the growth of Mo S2 nanosheets, along with rapid charge transfer kinetics. As-produced Mo S2/graphene nanocomposites exhibit superior electrocatalytic activity for the HER in acidic medium, with a low onset potential of62 m V, high cathodic currents and a Tafel slope of43.3 m V/decade. Beyond excellent catalytic activity, Mo S2/graphene reveals long cycling stability with a very high cathodic current density of around 1000 m A cm^-2 at an overpotential of 250 m V. Moreover, the Mo S2/graphene-catalyst exhibits outstanding HER activities in a temperature range of 30 to 120°C with low activation energy of36.51 k J mol^-1, providing the opportunity of practical scalable processing.

SnS2/graphene nanocomposite：A high rate anode material for lithium ion battery

In this work,via a facile solvothermal route,we synthesized an anode material for lithium ion batteries（LIBs）—SnS2 nanoparticle/graphene（SnS2 NP/GNs） nanocomposite.The nanocomposite consists of SnS2nanoparticles with an average diameter of 4 nm and graphene nanosheets without restacking.The SnS2 nanoparticles are firmly anchored on the graphene nanosheets.As an anode material for LIBs,the nanocomposite exhibits good Li storage performance especially high rate performance.At the high current rate of 5,10,and 20 A/g,the nanocomposite delivered high capacities of 525,443,and 378 mAh/g,respectively.The good conductivity of the graphene nanosheets and the small particle size of SnS2contribute to the electrochemical performance of SnS2 NP/GNs.

Recent advancements in biomedical application of polylactic acid/graphene nanocomposites:An overview

Polylactic acid(PLA)-graphene nanocomposites have attracted significant attention in the biomedical field because of their biodegradability,biocompatibility,and excellent mechanical properties.This review provides a comprehensive summary of the recent developments in the biomedical applications of PLA/graphene nanocomposites.The discussed applications include tissue engineering,drug delivery,biomedical imaging and sensing,antimicrobial and anticancer treatments,and photothermal and photodynamic therapies.The properties and synthesis of these nanocomposites are also addressed.This review shows that although significant advancements have been made in the development of biomedical applications for PLA/graphene nanocomposites,further research is still required to overcome the existing challenges and limitations,such as improving biocompatibility and biodegradability and optimizing synthesis and processing methods.Despite these challenges,the potential of PLA/graphene nanocomposites in the biomedical field is significant and holds promise for future advancements.

Constructing a multifunctional mesoporous composite of metallic cobalt nanoparticles and nitrogen-doped reduced graphene oxides for high-performance lithium-sulfur batteries

Electrochemical properties of lithium-sulfur(Li-S)batteries are mainly hindered by both the insulating nature of elemental sulfur(i.e.,molecular S8)and the shuttling effect or sluggish redox kinetics of lithium polysulfide intermediates(Li_(2)S_(n),3≤n≤8).In this paper,a three-dimensional mesoporous reduced graphene oxide-based nanocomposite,with the embedding of metallic Co nanoparticles and the doping of elemental N(Co/NrGO),and its simply ground mixture with powdered S at a mass ratio of 1:6(Co/NrGO/S)are prepared and used as cathode-/separator-coated interlayers and working electrodes in assembled Li-S cells,respectively.One of the effective cell configurations is to paste composite Co/NrGO onto both the S-loading cathode and separator,showing good cycling stability(1070mAh g^(−1) in the 100th cycle at 0.2 C),highrate capability(835mAh g^(−1),2.0 C),and excellent durability(905mAh g^(−1) in the 250th cycle at 0.5 or 0.2 C).Compared with the experimental results of Co-absent NrGO,electrochemical properties of various Co/NrGO-based cell configurations clearly show multiple functions of Co/NrGO,indicating that the absence of Co/NrGO coatings and/or Co nanoparticles may be inadequate to achieve superior S availability of assembled Li-S batteries.

Synthesis of butterfly-like BiVO4/RGO nanocomposites and their photocatalytic activities

A simple and high efficient method was proposed for the synthesis of uniform three dimensional （3D） BiVO4/reduced graphene oxide （RGO） nanocomposite photocatalyst by adopting the microwave assistant and using Bi （NO3）3·5H2O, graphene oxide （GO） and NH4VO3 as precursor. The as-obtained composites were well characterized with the aid of various techniques to study the morphology, structure, composition, optimal and electrical property. In the as-obtained composites, the GO sheets were fully reduced into RGO, and monoclinic structure BiVO4 crystallized completely into butterfly-like BiVO4 lamellas and well bonded with the RGO lamellas. The length and the width of the butterfly-like BiVO4 particle were about 1.5 μm, and the thickness of the flake was about 20 nm. Photocatalytic performances of BiVO4/RGO composite and pure BiVO4 particle have been evaluated by investigating the reduction of Cr（VI） ion-contained wastewater under simulated solar light irradiation, where the BiVO4/RGO composite displayed enhanced photocatalytic activity. It is found that the pseudo-first-order rate constants （k） for the photocatalytic reduction of Cr （VI） by BiVO4/RGO composite was about 4 times as high as that of the pure BiVO4. The present work suggested that the combination of BiVO4 and RGO displayed a remarkable synergistic effect, which led to enhanced photo-catalytic activity on Cr（VI） reduction.

Detection of dopamine at graphene-ZIF-8 nanocomposite modified electrode

A hybrid graphene-ZIF-8（G-ZIF-8） nanocomposite modified electrode was prepared in our work. SEM characterization shows that nanocrystals of zeolitic imidazolate frameworks（ZIF-8） were homogeneously well-intergrown on the surface of graphene and thus the graphene sheets were refrained from restacking, which implies the high accessible surface area. The BET results further testifies that G-ZIF-8composites had a larger surface area than 3D graphene. G-ZIF-8 modified electrode exhibited excellent electroanalytical performance for dopamine. The linear concentration range was from 3.0 mmol/L to1.0 mmol/L with the detection sensitivity of 0.34 m A/mmol/L and the detection limit of 1.0 mmol/L was obtained. The interference study, electrode stability and reproducibility were carried out. In addition, the prepared sensor was applied to the detection of DA in serum sample with recoveries from 96.8% to100.7%. It is believable that the structure characteristic of G-ZIF-8 nanocomposite is favorable for using MOFs to fabricate highly sensitive electrochemical sensor

Electrochemical Biosensors for Detecting Microbial Toxins by Graphene‑Based Nanocomposites

It is important to develop methods to determine microbial toxins at trace levels since these toxins are ubiquitous commonly found in water and foods,and pose potential threats to both human health and ecosystem safety.Taking the advantages of ultrahigh electron-transfer capability,extra-large surface area and easily functionalized ability,the graphene-based nanocomposites have been employed to fabricate electrochemical biosensors including immunosensors and aptasensors for detecting microbial toxins with high sensitivity.The specificity and selectivity of the electrochemical biosensors for targeting toxins can be achieved by combining graphene nanocomposites with antibodies and/or aptamers.The graphene nanocompositebased electrochemical biosensors could become a promising technique in the detection of microbial toxins for public and environmental health protection.

SnO_2-Decorated Graphene/Polyaniline Nanocomposite for a High-Performance Supercapacitor Electrode

An SnO2-decorated graphene/polyaniline （GSP） nanocomposite with homogeneous structure was prepared and adopted to achieve high electrochemical performance for supercapacitor electrode. Graphene sheets were decorated with tin dioxide （SnO2） particles, which effectively hinder the restacking of graphene nanosheets, and then were used as substrates for an in-situ polymerization of aniline monomers. The GSP nanocomposite was characterized by field emission scanning electron microscopy, X-ray diffraction, Fourier transform infrared, UV-Visible and X-ray photoelectron spectroscopy. The results revealed that polyaniline nanorods were orderly and vertically aligned on the SnO2-decorated graphene nanosheets via π-π stacking effect between basal planes of graphene nanosheets and phenyl group of polyaniline. The GSP nanocomposite exhibited an excellent specific capacitance of 429 F g^-1 at a current density of 1 A g^-1, excellent cycling stability and rate capability, which suggested a promising application for supercapacitor.

Low Temperature Reduction of Graphene Oxide Using Hot-plate for Nanocomposites Applications

A green, easy to reproduce method to obtain thermally reduced graphene oxide （GO） is described, The only requirement is a heating source, like a hot plate, that can reach -225 ℃ without any special setup requirements. Upon addition of graphene oxide, effective reduction could be achieved within 10 s. Starting flake size affects the yield of graphene, final structure and composition. A detailed characterization of the produced graphene using thermal analysis, spectroscopic methods, electron microscopy, X-ray diffraction and atomic force microscopy is presented. Application of the produced graphene as a filler to epoxy resin for mechanical reinforcement is also reported. Smaller flakes （Ds0 = 5.7 μm） showed improved ultimate tensile strength, fracture strain and plane strain fracture toughness compared to larger flakes （Ds0 = 47.9 μm） that showed negative effect. Both flake sizes showed a negligible effect on Young＇s modulus.

Au nanoparticles decorated graphene/nickel foam nanocomposite for sensitive detection of hydrogen peroxide

The Au nanoparticles decorated graphene（AuNPs@Gr）/nickel foam（Gr/NiF） nanocomposite（AuNPs@Gr/NiF） was prepared by chemical vapor deposition followed by electrophoretic deposition of AuNPs on Gr/NiF. The morphology, microstructure and sensing performance of the as-prepared AuNPs@Gr/NiF nanocomposite were characterized and measured, respectively by scanning electron microscope, transmission electron microscope, ultraviolet visible spectroscopy and chemical workstation. The asprepared AuNPs@Gr/NiF nanocomposite was used as the electrode to construct a chemical sensor for the detection of hydrogen peroxide（H2O2）. The results showed that the AuNPs distributed homogenously and stably on the surface of Gr/NiF. The chemical sensor exhibits a sensitive and selective performance to the detection of H2O2.

Enhanced microwave absorption performance of highly dispersed CoNi nanostructures arrayed on graphene

Magnetic metals （Fe, Co, Ni） and alloys thereof are easily synthesized as nanoparticles, but obtaining highly dispersed graphene-based magnetic nanomaterials remains challenging. Here, three CoNi/graphene nanocomposites （CoNi/GN） are successfully assembled for the first time via a one-pot strategy without templating by manipulating the reaction time and solvents used for the same precursors. Moreover, the reduction of graphene oxide utilizing this method is more effective than that by conventional methods and the alloy particles are firmly embedded on the GN substrate. Compared to n- and p-CoNi/GN nanocomposites, o-CoNi/GN nanocomposites show the best electromagnetic wave absorption properties with the maximum reflection loss of -31.0 dB at 4.9 GHz for a thickness of 4 mm; the effective absorption bandwidth （〈 10.0 dB） is 7.3 GHz （9.5-16.8 GHz） for a thickness of 2 mm. The structures and electromagnetic wave absorption mechanisms of the three composites were also investigated. This research provides a new platform for the development of magnetic alloy nanoparticles in the field of microwave-absorbing devices.

A Facile Way to Large-scale Production of Few-layered Graphene via Planetary Ball Mill

Abstract In the field of polymer/graphene nanocomposites, massive production and commercial availability of graphene are essential. Exfoliation of graphite to obtain graphene is one of the most promising ways to large-scale production at extremely low cost. In this work we illustrate a facile strategy for mass production of few-layered （≤ 10） graphene （FLG） via the newly explored ball milling. The achieved FLG concentration was determined by UV/Vis spectroscopy. The formation of FLG was proved by measuring the flake thickness by atomic force microscopy （AFM）. Further Raman spectral studies indicated that the crystal structure of exfoliated flakes was preserved satisfactorily during this shear-force dominating process. To increase the maximum concentration obtainable, it＇s critical to make a good parameter assessment. N-methylpyrrolidone （NMP） was used as a dispersing medium and the effect of milling parameters was systematically and quantitatively investigated, thus providing a criterion to optimize the milling process. We established the optimal values for solvent volume and initial weight of graphite. As for milling time, the production of FLG was enhanced with continuous milling according to the power law, but not linearly with increasing milling time. Moreover, the possible mechanism involved in milling process was also explored. Our work provides a simple method for graphite exfoliation and has great potential for improving thermal and electrical conductivity of polymer composites in the fields of engineering.

Nanoarchitectured LiMn_2O_4/Graphene/ZnO Composites as Electrodes for Lithium Ion Batteries

LiMn2O4 nanoparticles are facilely synthesized using a sol-gel processing method. Graphene is added to LiMn2O4 electrode aiming at increasing specific capacity and improving rate capability. In order to further improve cycling stability of LiMn2O4/graphene electrode, atomic layer deposition （ALD） is used to deposit ultrathin ZnO coating composed of six ZnO ALD layers and modify the surface of either LiMn2O4/graphene electrode or individual LiMn2O4 particles to form nanoarchitectured LiMn2O4/graphene/ZnO electrodes. Both ZnO-ALD-modified LiMn2O4/graphene electrodes demonstrate enhanced cycling performance at 1C, retaining the final discharge capacity above 122 mA h g 1 after 100 electrochemical cycles, which is higher than 115 mA h g-1 of pristine LiMn2O4/graphene electrode and 109 mA h g-1 of bare LiMn2O4 electrode. The improved electrochemical performance of nanoarchitectured LiMn2O4/graphene/ZnO electrodes can be attributed to the cooperative effects from high electronic conductivity of graphene sheets to facilitate electron transportation and effective protection of ZnO ALD coating to restrict Mn dissolution and electrolyte decomposition.

Influence of graphene nanoplatelet incorporation and dispersion state on thermal, mechanical and electrical properties of biodegradable matrices

Graphene nanoplatelets （GNPs） were used as multifunctional nanofiller to enhance thermal and mechanical properties as well as electrical conductivity of two different biodegradable thermoplastics： poly lactide （PLA） and poly （butylene adipate-co-terephthalate） （PBAT）. Morphological investigations showed different levels of GNP dispersion in the two matrices, and consequently physical properties of the two systems exhibited dissimilar behaviours with GNP incorporation. Crystallinity of PLA, determined from differential scanning calorimetry, was observed to increase markedly with addition of GNPs in contrast to the decrease in crystallinity of PBAT. Isothermal and non-isothermal thermogravimetric analyses also revealed a more significant delay in thermal decomposition of PLA upon addition of GNPs compared to that of PBAT. Furthermore, results showed that increasing GNP content of PLA and PBAT nanocomposites influenced their Young＇s modulus and electrical conductivity in different ways. Modulus of PBAT increased continuously with increasing GNP loading while that of PLA reached a maximum at 9wt% GNPs and then decreased. Moreover, despite the higher conductivity of pure PBAT compared to pure PLA, conductivity of PLA/GNP nanocomposites overtook that of PBATIGNP nanocomposites above a certain GNP concentration. This demonstrated the determining effect of nanoplatelets dispersion state on the matrices properties.

Mesoporous WO_3-graphene photocatalyst for photocatalytic degradation of Methylene Blue dye under visible light illumination

Advanced oxidation technologies are a friendly environmental approach for the remediation of industrial wastewaters. Here, one pot synthesis of mesoporous WO3 and WO3-graphene oxide（GO） nanocomposites has been performed through the sol–gel method. Then, platinum（Pt） nanoparticles were deposited onto the WO3 and WO3-GO nanocomposite through photochemical reduction to produce mesoporous Pt/WO3 and Pt/WO3-GO nanocomposites. X-ray diffraction（XRD） findings exhibit a formation of monoclinic and triclinic WO3 phases. Transmission Electron Microscope（TEM） images of Pt/WO3-GO nanocomposites exhibited that WO3 nanoparticles are obviously agglomerated and the particle sizes of Pt and WO3 are ~ 10 nm and 20–50 nm, respectively. The mesoporous Pt/WO3 and Pt/WO3-GO nanocomposites were assessed for photocatalytic degradation of Methylene Blue（MB） as a probe molecule under visible light illumination.The findings showed that mesoporous Pt/WO3, WO3-GO and Pt/WO3-GO nanocomposites exhibited much higher photocatalytic efficiencies than the pure WO3. The photodegradation rates by mesoporous Pt/WO3-GO nanocomposites are 3, 2 and 1.15 times greater than those by mesoporous WO3, WO3-GO, and Pt/WO3, respectively. The key factors of the enhanced photocatalytic performance of Pt/WO3-GO nanocomposites could be explained by the highly freedom electron transfer through the synergetic effect between WO3 and GO sheets, in addition to the Pt nanoparticles that act as active sites for O2 reduction, which suppresses the electron hole pair recombination in the Pt/WO3-GO nanocomposites.

Fabrication of the electrochemically reduced graphene oxide-bismuth nanoparticles composite and its analytical application for an anticancer drug gemcitabine

The present study explores an electroreduced graphene oxide-bismuth nanoparticles composite（ErGOBi） as an electrochemical sensor for the determination of an anticancer drug, gemcitabine hydrochloride（GMB）. The Er-GOBi interface was prepared by drop casting of bismuth nitrate-graphene oxide suspension on a glassy carbon electrode（GCE） followed by electro-reduction in the potential range of 0.6 V to 1.7 V. SEM, FTIR, EDAX and AFM techniques were employed for the characterization of prepared materials. Cyclic voltammetric and electrochemical impedance spectroscopic methods were used to understand the charge transfer properties of stepwise modification of Er-GOBi/GCE. GMB exhibited an irreversible oxidation peak at 1.144 V on Er-GOBi/GCE in phosphate buffer of p H 3. A 100-fold enhanced oxidation peak current was observed at Er-GOBi/GCE when compared to that at bare GCE.Sensing performance of Er GO-Bi/GCE was optimized by varying peak current dependent parameters.Linear relationship between the peak current and concentration of GMB was observed in the range of 0.1–51.1 mmol/L in differential pulse voltammetric method and 2.1–61.1 mmol/L in linear sweep voltammetric method. The practical utility of the proposed sensor, Er-GOBi/GCE was demonstrated by determining GMB in pharmaceutical formulations and spiked urine samples.

One-pot solvothermal synthesis of ZnTe/RGO nanocomposites and enhanced visible-light photocatalysis

Zinc telluride/reduced graphene oxide （ZnTe/RGO） nanocomposites are synthesized by a one-pot, facile, solvothermal process using hydrazine hydrate as the reducing agent. Hydrazine hydrate not only promoted the formation ofZnTe nanoparticles but also reduced GO to RGO. The formation of ZnTe/RGO is demonstrated by different techniques. In addition, the experimental results suggest a possible formation mechanism of these nanocomposites. Finally, due to the transfer of the photo-generated electrons between ZnTe and RGO resulting in low electrons/holes recombination, the as-prepared nanocomposites of ZnTe/RGO exhibited strongly enhanced photocatalytic activity for the bleaching of methyl blue （MB） dye under visible light irradiation.