Showing papers on "Nanocomposite published in 2017"

Two dimensional hexagonal boron nitride (2D-hBN): synthesis, properties and applications

Abstract: Two dimensional hexagonal boron nitride (2D-hBN), an isomorph of graphene with a very similar layered structure, is uniquely featured by its exotic opto-electrical properties together with mechanical robustness, thermal stability, and chemical inertness. It is thus extensively studied for application in field effect transistors (FETs), tunneling devices, deep UV emitters and detectors, photoelectric devices, and nanofillers. 2D-hBN is considered as one of the most promising materials that can be integrated with other 2D materials, such as graphene and transition metal dichalcogenides (TMDCs), for the next generation microelectronic and other technologies. Although it is by itself an insulator, it can well be tuned by several strategies in terms of properties and functionalities, such as by doping, substitution, functionalization and hybridization, making 2D-hBN a truly versatile type of functional materials for a wide range of applications. In this review, the distinct structural characteristics of 2D-hBN, doping- and defect-induced variations in energy bands and structures, and resultant properties, are presented. There are a wide variety of processing routes that have been developed for 2D-hBN, including also those for doping, substitution, functionalization and combination with other materials to form heterostructures or h-BNC hybrid nanosheets, which are systematically elaborated for novel functions. The comprehensive overview provides the types of the state-of-the-art 2D-hBN made by new synthesis strategies, where the mainstream approaches include exfoliation, chemical vapor deposition, and gas phase epitaxy, together with several other new methods that have been successfully developed in the past few years. On the basis of the extraordinary electrical and functional properties and thermal–mechanical stability, the applications of hBN-based nanosheets as substrates and dielectrics, passivation layers, and nanofillers in nanodevices and nanocomposites are discussed, together with the peculiar optical and wetting characteristics.

Cellulose Nanofiber Supported 3D Interconnected BN Nanosheets for Epoxy Nanocomposites with Ultrahigh Thermal Management Capability

Abstract: Thermally conductive but electrically insulating polymer composites are highly desirable for thermal management applications because of their wide range of utilization, ease of processing, and low cost. However, the traditional approaches to thermally conductive polymer composites usually suffer from the low thermal conductivity enhancement and/or the deterioration of electrical insulating property. In this study, using cellulose nanofiber-supported 3D interconnected boron nitride nanosheet (3D–C–BNNS) aerogels, a novel method for highly thermally conductive but electrically insulating epoxy nanocomposites is reported. The nanocomposites exhibit thermal conductivity enhancement of about 1400% at a low BNNS loading of 9.6 vol%. In addition, the epoxy nanocomposites are still highly insulating, having a volume electrical resistivity of 1015 Ω cm. The strong potential application for thermal management has been demonstrated by the surface temperature variations of the nanocomposites with time during heating and cooling.

Highly Conductive Transition Metal Carbide/Carbonitride(MXene)@polystyrene Nanocomposites Fabricated by Electrostatic Assembly for Highly Efficient Electromagnetic Interference Shielding

Abstract: Highly conductive polymer nanocomposites are greatly desired for electromagnetic interference (EMI) shielding applications. Although transition metal carbide/carbonitride (MXene) has shown its huge potential for producing highly conductive films and bulk materials, it still remains a great challenge to fabricate extremely conductive polymer nanocomposites with outstanding EMI shielding performance at minimal amounts of MXenes. Herein, an electrostatic assembly approach for fabricating highly conductive MXene@polystyrene nanocomposites by electrostatic assembling of negative MXene nanosheets on positive polystyrene microspheres is demonstrated, followed by compression molding. Thanks to the high conductivity of MXenes and their highly efficient conducting network within polystyrene matrix, the resultant nanocomposites exhibit not only a low percolation threshold of 0.26 vol% but also a superb conductivity of 1081 S m−1 and an outstanding EMI shielding performance of >54 dB over the whole X-band with a maximum of 62 dB at the low MXene loading of 1.90 vol%, which are among the best performances for electrically conductive polymer nanocomposites by far. Moreover, the same nanocomposite has a highly enhanced storage modulus, 54% and 56% higher than those of neat polystyrene and conventional MXene@polystyrene nanocomposite, respectively. This work provides a novel methodology to produce highly conductive polymer nanocomposites for highly efficient EMI shielding applications.

Three-dimensional printing of transparent fused silica glass

Abstract: Using stereolithography 3D printers, a silica nanocomposite is shaped and then fused to produce non-porous, very smooth, highly transparent fused silica glass components. Fused silica glass has long been known for its excellent optical properties, yet processing and patterning this material still requires high-temperature processes and/or hazardous chemical materials. To simplify such processes, Bastian Rapp and colleagues have been developing a system—termed 'liquid glass'—in which a viscous amorphous silica nanocomposite can be patterned into complex shapes by moulding and then photocured to produce optical-quality glass structures. In their latest development, the group have tuned the properties of their nanocomposite to facilitate its use in a 3D printer, yielding high-optical-quality glass structures with features as small as a few tens of micrometres. Glass is one of the most important high-performance materials used for scientific research, in industry and in society, mainly owing to its unmatched optical transparency, outstanding mechanical, chemical and thermal resistance as well as its thermal and electrical insulating properties1,2,3. However, glasses and especially high-purity glasses such as fused silica glass are notoriously difficult to shape, requiring high-temperature melting and casting processes for macroscopic objects or hazardous chemicals for microscopic features3,4. These drawbacks have made glasses inaccessible to modern manufacturing technologies such as three-dimensional printing (3D printing). Using a casting nanocomposite5, here we create transparent fused silica glass components using stereolithography 3D printers at resolutions of a few tens of micrometres. The process uses a photocurable silica nanocomposite that is 3D printed and converted to high-quality fused silica glass via heat treatment. The printed fused silica glass is non-porous, with the optical transparency of commercial fused silica glass, and has a smooth surface with a roughness of a few nanometres. By doping with metal salts, coloured glasses can be created. This work widens the choice of materials for 3D printing, enabling the creation of arbitrary macro- and microstructures in fused silica glass for many applications in both industry and academia.

Pseudocapacitive Sodium Storage in Mesoporous Single-Crystal-like TiO2–Graphene Nanocomposite Enables High-Performance Sodium-Ion Capacitors

Abstract: Sodium-ion capacitors can potentially combine the virtues of high power capability of conventional electrochemical capacitors and high energy density of batteries. However, the lack of high-performance electrode materials has been the major challenge of sodium-based energy storage devices. In this work, we report a microwave-assisted synthesis of single-crystal-like anatase TiO2 mesocages anchored on graphene as a sodium storage material. The architecture of the nanocomposite results in pseudocapacitive charge storage behavior with fast kinetics, high reversibility, and negligible degradation to the micro/nanostructure. The nanocomposite delivers a high capacity of 268 mAh g–1 at 0.2 C, which remains 126 mAh g–1 at 10 C for over 18 000 cycles. Coupling with a carbon-based cathode, a full cell of sodium-ion capacitor successfully demonstrates a high energy density of 64.2 Wh kg–1 at 56.3 W kg–1 and 25.8 Wh kg–1 at 1357 W kg–1, as well as an ultralong lifespan of 10 000 cycles with over 90% of capacity rete...

A Review on Design Strategies for Carbon Based Metal Oxides and Sulfides Nanocomposites for High Performance Li and Na Ion Battery Anodes

Abstract: Carbon-oxide and carbon-sulfide nanocomposites have attracted tremendous interest as the anode materials for Li and Na ion batteries. Such composites are fascinating as they often show synergistic effect compared to their singular components. Carbon nanomaterials are often used as the matrix due to their high conductivity, tensile strength, and chemical stability under the battery condition. Metal oxides and sulfides are often used as active material fillers because of their large capacity. Numerous works have shown that by taking one step further into fabricating nanocomposites with rational structure design, much better performance can be achieved. The present review aims to present and discuss the development of carbon-based nanocomposite anodes in both Li ion batteries and Na ion batteries. The authors introduce the individual components in the composites, i.e., carbon matrices (e.g., carbon nanotube, graphene) and metal oxides/sulfides; followed by evaluating how advanced nanostructures benefit from the synergistic effect when put together. Particular attention is placed on strategies employed in fabricating such composites, with examples such as yolk–shell structure, layered-by-layered structure, and composite comprising one or more carbon matrices. Lastly, the authors conclude by highlighting challenges that still persist and their perspective on how to further develop the technologies.

Novel Metal–Organic Framework (MOF) Based Composite Material for the Sequestration of U(VI) and Th(IV) Metal Ions from Aqueous Environment

Abstract: The combination of magnetic nanoparticles and metal–organic frameworks (MOFs) has demonstrated their prospective for pollutant sequestration. In this work, a magnetic metal–organic framework nanocomposite (Fe3O4@AMCA-MIL53(Al) was prepared and used for the removal of U(VI) and Th(IV) metal ions from aqueous environment. Fe3O4@AMCA-MIL53(Al) nanocomposite was characterized by TGA, FTIR, SEM-EDX, XRD, HRTEM, BET, VSM (vibrating sample magnetometry), and XPS analyses. A batch technique was applied for the removal of the aforesaid metal ions using Fe3O4@AMCA-MIL53(Al) at different operating parameters. The isotherm and kinetic data were accurately described by the Langmuir and pseudo-second-order models. The adsorption capacity was calculated to be 227.3 and 285.7 mg/g for U(VI) and Th(IV), respectively, by fitting the equilibrium data to the Langmuir model. The kinetic studies demonstrated that the equilibrium time was 90 min for each metal ion. Various thermodynamic parameters were evaluated which indicated...

A Combination of Boron Nitride Nanotubes and Cellulose Nanofibers for the Preparation of a Nanocomposite with High Thermal Conductivity

Abstract: With the current development of modern electronics toward miniaturization, high-degree integration and multifunctionalization, considerable heat is accumulated, which results in the thermal failure or even explosion of modern electronics. The thermal conductivity of materials has thus attracted much attention in modern electronics. Although polymer composites with enhanced thermal conductivity are expected to address this issue, achieving higher thermal conductivity (above 10 W m–1 K–1) at filler loadings below 50.0 wt % remains challenging. Here, we report a nanocomposite consisting of boron nitride nanotubes and cellulose nanofibers that exhibits high thermal conductivity (21.39 W m–1 K–1) at 25.0 wt % boron nitride nanotubes. Such high thermal conductivity is attributed to the high intrinsic thermal conductivity of boron nitride nanotubes and cellulose nanofibers, the one-dimensional structure of boron nitride nanotubes, and the reduced interfacial thermal resistance due to the strong interaction betwe...

Elevated Performance of Thin Film Nanocomposite Membranes Enabled by Modified Hydrophilic MOFs for Nanofiltration.

Abstract: Metal–organic frameworks (MOFs) are studied for the design of advanced nanocomposite membranes, primarily due to their ultrahigh surface area, regular and highly tunable pore structures, and favorable polymer affinity. However, the development of engineered MOF-based membranes for water treatment lags behind. Here, thin-film nanocomposite (TFN) membranes containing poly(sodium 4-styrenesulfonate) (PSS) modified ZIF-8 (mZIF) in a polyamide (PA) layer were constructed via a facile interfacial polymerization (IP) method. The modified hydrophilic mZIF nanoparticles were evenly dispersed into an aqueous solution comprising piperazine (PIP) monomers, followed by polymerizing with trimesoyl chloride (TMC) to form a composite PA film. FT-IR spectroscopy and XPS analyses confirm the presence of mZIF nanoparticles on the top layer of the membranes. SEM and AFM images evince a retiform morphology of the TFN-mZIF membrane surface, which is intimately linked to the hydrophilicity and adsorption capacity of mZIF nanopa...

High-Energy-Density Dielectric Polymer Nanocomposites with Trilayered Architecture

Abstract: The development of advanced dielectric materials with high electric energy densities is of crucial importance in modern electronics and electric power systems. Here, a new class of multilayer-structured polymer nanocomposites with high energy and power densities is presented. The outer layers of the trilayered structure are composed of boron nitride nanosheets dispersed in poly(vinylidene fluoride) (PVDF) matrix to provide high breakdown strength, while PVDF with barium strontium titanate nanowires forms the central layer to offer high dielectric constant of the resulting composites. The influence of the filler contents on the electrical polarization, breakdown strength, and energy density is examined. Simulations are carried out to model the electrical tree formation in the layered nanocomposites and to verify the experimental breakdown results. The trilayered polymer nanocomposite with an optimized filler content displays a discharged energy density of 20.5 J cm−3 at Weibull breakdown strength of 588 MV m−1, which is among the highest discharged energy densities reported so far. Moreover, the nanocomposite exhibits a superior power density of 0.91 MW cm−3, more than nine times that of the commercially available biaxially oriented polypropylene. The findings of this research provide a new design paradigm for high-performance dielectric polymer nanocomposites.

Ultralow percolation threshold and enhanced electromagnetic interference shielding in poly(L-lactide)/multi-walled carbon nanotube nanocomposites with electrically conductive segregated networks

Abstract: Electrically conductive segregated networks were built in poly(L-lactide)/multi-walled carbon nanotube (PLLA/MWCNT) nanocomposites without sacrificing their mechanical properties via simply choosing two different PLLA polymers with different viscosities and crystallinities. First, the MWCNTs were dispersed in PLLA with low viscosity and crystallinity (L-PLLA) to obtain the L-PLANT phase. Second, the PLLA particles with high viscosity and crystallinity (H-PLLA) were well coated with the L-PLANT phase at 140 °C which was below the melting temperature of H-PLLA. Finally, the coated H-PLLA particles were compressed above the melting temperature of H-PLLA to form the PLLA/MWCNT nanocomposites with segregated structures. The morphological observation showed the successful location of MWCNTs in the continuous L-PLLA phase, resulting in an ultralow percolation threshold of 0.019 vol% MWCNTs. The electrical conductivity and the electromagnetic interference (EMI) shielding effectiveness (SE) of the composites with the segregated structure are 25 S m−1 and ∼30 dB, showing three orders and 36% higher than that of the samples with a random distribution of MWCNTs with 0.8 vol% of MWCNT loading, respectively. High-performance electromagnetic interference (EMI) shielding was also observed mainly dependent on the highly efficient absorption shielding, which can be achieved by the densely continuous MWCNT networks and the abundant interfaces induced by the segregated structures. Furthermore, the composites with segregated structures not only showed higher Young's modulus and tensile strength than the corresponding conventional composites, but also maintained high elongation at break because of the continuous and dense MWCNT networks induced by the segregated structures and the high interfacial interaction between H-PLLA and L-PLLA.

Rational Design of Three-Dimensional Graphene Encapsulated with Hollow FeP@Carbon Nanocomposite as Outstanding Anode Material for Lithium Ion and Sodium Ion Batteries.

Abstract: Transition metal phosphides have been extensively investigated owing to their high theoretical capacities and relatively low intercalation potentials vs Li/Li+, but their practical applications have been hindered by low electrical conductivity and dramatic volume variation during cycling. In this work, an interesting strategy for the rational design of graphene (GR) encapsulated with a hollow FeP@carbon nanocomposite (H-FeP@C@GR) via a combination of a hydrothermal route, a carbon-coating process, phosphidation treatment, and carbothermic reaction is reported. The hollow FeP (H-FeP) nanospheres shelled with thin carbon layers are wonderfully incorporated into the GR matrix, interconnecting to form a three-dimensional (3D) hierarchical architecture. Such a design offers distinct advantages for FeP-based anode materials for both lithium ion batteries (LIBs) and sodium ion batteries (SIBs). For example, the 3D omnibearing conductive networks from the GR skeleton and outer coating carbon can provide an open f...

3D Printing Biocompatible Polyurethane/Poly(lactic acid)/Graphene Oxide Nanocomposites: Anisotropic Properties

Abstract: Blending thermoplastic polyurethane (TPU) with poly(lactic acid) (PLA) is a proven method to achieve a much more mechanically robust material, whereas the addition of graphene oxide (GO) is increasingly applied in polymer nanocomposites to tailor further their properties. On the other hand, additive manufacturing has high flexibility of structure design which can significantly expand the application of materials in many fields. This study demonstrates the fused deposition modeling (FDM) 3D printing of TPU/PLA/GO nanocomposites and its potential application as biocompatible materials. Nanocomposites are prepared by solvent-based mixing process and extruded into filaments for FDM printing. The addition of GO largely enhanced the mechanical property and thermal stability of the nanocomposites. Interestingly, we found that the mechanical response is highly dependent on printing orientation. Furthermore, the 3D printed nanocomposites exhibit good biocompatibility with NIH3T3 cells, indicating promise as biomat...

Room-temperature SO2 gas-sensing properties based on a metal-doped MoS2 nanoflower: an experimental and density functional theory investigation

Abstract: This paper demonstrates a sulfur dioxide (SO2) gas sensor based on a transition-metal-doped molybdenum disulfide (MoS2) nanocomposite synthesized via a facile single-step hydrothermal route. The Ni-doped, Fe-doped, Co-doped, and pristine MoS2 film sensors were fabricated on a FR4 epoxy substrate with interdigital electrodes. The morphologies, microstructures, and compositions of as-prepared samples were fully examined using X-ray diffraction, energy dispersive spectroscopy, scanning electron microscopy, transmission electron microscope, and X-ray photoelectron spectroscopy. The gas-sensing properties of the four samples were systematically investigated at room temperature, and the Ni-doped MoS2 film sensor was screened out as the optimal SO2 sensor among the four sensors, exhibiting a relatively high response value, quick response/recovery time, and excellent stability toward SO2 gas. Furthermore, in order to explain the experimental results, we used Materials Studio software to construct molecular models of adsorption systems and calculate the geometry, energy, and charge parameters via density functional theory (DFT) based on first principles. The sensing mechanism is also discussed in depth. Through a comprehensive research approach of combining experimentation with DFT simulation, this work suggests that an Ni-doped MoS2 film sensor is able to detect SO2 gas at room temperature.

Thin-Film Nanocomposite (TFN) Membranes Incorporated with Super-Hydrophilic Metal–Organic Framework (MOF) UiO-66: Toward Enhancement of Water Flux and Salt Rejection

Abstract: Zirconiumv (IV)-carboxylate metal–organic framework (MOF) UiO-66 nanoparticles were successfully synthesized and incorporated in the polyamide (PA) selective layer to fabricate novel thin-film nanocomposite (TFN) membranes. Compared to unmodified pure polyamide thin-film composite (TFC) membranes, the incorporation of UiO-66 nanoparticles significantly changes the membrane morphology and chemistry, leading to an improvement of intrinsic separation properties due to the molecular sieving and superhydrophilic nature of UiO-66 particles. The best performing TFN-U2 (0.1 wt % particle loading) membrane not only shows a 52% increase of water permeability but also maintains salt rejection levels (∼95%) similar to the benchmark. The effects of UiO-66 loading on the forward osmosis (FO) performance were also investigated. Incorporation of 0.1 wt % UiO-66 produced a maximum water flux increase of 40% and 25% over the TFC control under PRO and FO modes, when 1 M NaCl was used as the draw solution against deionized w...

Graphene Oxide Quantum Dots Incorporated into a Thin Film Nanocomposite Membrane with High Flux and Antifouling Properties for Low-Pressure Nanofiltration.

Abstract: Graphene oxide quantum dots (GOQDs), novel carbon-based nanomaterials, have attracted tremendous research interest due to their unique properties associated with both graphene and quantum dots. In the present study, thin film nanocomposite (TFN) membranes comprising GOQDs dispersed within a tannic acid (TA) film were fabricated by an interfacial polymerization reaction for low-pressure nanofiltration (NF). The resultant TA/GOQDs TFN membranes had measurably smoother and more hydrophilic, negatively charged surfaces compared to the similarly formed TA thin film composite (TFC) membrane. Owing to the loose active layer structure and the combination of Donnan exclusion and steric hindrance, the TA/GOQDs TFN membrane showed a pure water flux up to 23.33 L/m2·h (0.2 MPa), which was 1.5 times more than that of pristine TA TFC membrane, while high dye rejection to Congo red (99.8%) and methylene blue (97.6%) was kept. In addition, the TA/GOQDs TFN membrane presented better antifouling properties, which was ascri...

In situ synthesis of C-TiO2/g-C3N4 heterojunction nanocomposite as highly visible light active photocatalyst originated from effective interfacial charge transfer

Abstract: In this paper, a simple one-pot hydrothermal strategy was adopted to prepare C-TiO2/g-C3N4 nanocomposite. Simultaneously, the photocatalytic performance of the C-TiO2/g-C3N4 nanocomposite like tunable ratio was evaluated by the degradation of methyl orange (MO) under visible light irradiation. The prepared nanocomposite with the mass ratio of 27:8 (C-TiO2/g-C3N4(0.08)) possessed the highest photocatalytic activity, about 5.1, 3.8 and 2.3 times higher than that of C-TiO2, g-C3N4, and the Mixing sample, respectively. The excellent photocatalytic performance was attributed to the improvement of light harvesting and charge separation caused by construction of heterojunction. In addition, interfacial charge transfer through CTi bond and NTi bond also played a crucial role in inhibiting the recombination of electron-hole pairs and increasing the concentrations of holes and electrons, separately, which was confirmed by XPS analysis, photocurrent response experiment, electrochemical impedance spectroscopy measurements, PL spectra and Time-resolved PL spectra. Besides, the importance of active species during the reaction process was explored, and the generation of h+, O2−, OH in the photocatalytic process was also demonstrated. Among this, O2− played an important role. This finding about chemically bonded C-TiO2/g-C3N4 nanocomposite provided a good guidance for the fabrication of new heterogeneous photocatalysts and facilitated their applications in environmental protection, water splitting and so on.

Vertically Aligned and Interconnected Boron Nitride Nanosheets for Advanced Flexible Nanocomposite Thermal Interface Materials

Abstract: The continuous evolution toward semiconductor technology in the “more-than-Moore” era and rapidly increasing power density of modern electronic devices call for advanced thermal interface materials (TIMs). Here, we report a novel strategy to construct flexible polymer nanocomposite TIMs for advanced thermal management applications. First, aligned polyvinyl alcohol (PVA) supported and interconnected 2D boron nitride nanosheets (BNNSs) composite fiber membranes were fabricated by electrospinning. Then, the nanocomposite TIMs were constructed by rolling the PVA/BNNS composite fiber membranes to form cylinders and subsequently vacuum-assisted impregnation of polydimethylsiloxane (PDMS) into the porous cylinders. The nanocomposite TIMs not only exhibit a superhigh through-plane thermal conductivity enhancement of about 10 times at a low BNNS loading of 15.6 vol % in comparison with the pristine PDMS but also show excellent electrical insulating property (i.e., high volume electrical resistivity). The outstandi...

Bioinspired Nanocomposite Hydrogels with Highly Ordered Structures

Abstract: In the human body, many soft tissues with hierarchically ordered composite structures, such as cartilage, skeletal muscle, the corneas, and blood vessels, exhibit highly anisotropic mechanical strength and functionality to adapt to complex environments. In artificial soft materials, hydrogels are analogous to these biological soft tissues due to their "soft and wet" properties, their biocompatibility, and their elastic performance. However, conventional hydrogel materials with unordered homogeneous structures inevitably lack high mechanical properties and anisotropic functional performances; thus, their further application is limited. Inspired by biological soft tissues with well-ordered structures, researchers have increasingly investigated highly ordered nanocomposite hydrogels as functional biological engineering soft materials with unique mechanical, optical, and biological properties. These hydrogels incorporate long-range ordered nanocomposite structures within hydrogel network matrixes. Here, the critical design criteria and the state-of-the-art fabrication strategies of nanocomposite hydrogels with highly ordered structures are systemically reviewed. Then, recent progress in applications in the fields of soft actuators, tissue engineering, and sensors is highlighted. The future development and prospective application of highly ordered nanocomposite hydrogels are also discussed.

Fe3O4-functionalized graphene nanosheet embedded phase change material composites: efficient magnetic- and sunlight-driven energy conversion and storage

Abstract: As an important energy utilization mode, thermal energy is closely related to human life and social production. Phase change materials have been widely adopted to store thermal energy to improve its utilization efficiency. However, the inherent low energy conversion ability of these materials is one of the key problems to be resolved urgently. In this paper, we report novel magnetic- and sunlight-driven energy conversion and storage nanocomposites based on Fe3O4-functionalized graphene nanosheet (Fe3O4–GNS) embedded form-stable polymer phase change materials. Owing to the excellent magnetocaloric performance of Fe3O4 and the universal photoabsorption and photothermal conversion of graphene, the nanocomposites can effectively convert magnetic or light energy into thermal energy under an alternating magnetic field or solar illumination. The energy is stored by phase change materials during the phase transition process. The obtained hybrid nanocomposites exhibit excellent thermal stability with high melting–freezing enthalpy and excellent reversibility. Furthermore, the novel nanocomposites show the characteristics of form-stable phase transformation. The Fe3O4–GNS embedded phase change material composites for energy conversion and storage are expected to open up a rich field of energy materials.