Showing papers on "Nanocomposite published in 2016"

Recent Progress on Ferroelectric Polymer-Based Nanocomposites for High Energy Density Capacitors: Synthesis, Dielectric Properties, and Future Aspects.

Abstract: Dielectric polymer nanocomposites are rapidly emerging as novel materials for a number of advanced engineering applications. In this Review, we present a comprehensive review of the use of ferroelectric polymers, especially PVDF and PVDF-based copolymers/blends as potential components in dielectric nanocomposite materials for high energy density capacitor applications. Various parameters like dielectric constant, dielectric loss, breakdown strength, energy density, and flexibility of the polymer nanocomposites have been thoroughly investigated. Fillers with different shapes have been found to cause significant variation in the physical and electrical properties. Generally, one-dimensional and two-dimensional nanofillers with large aspect ratios provide enhanced flexibility versus zero-dimensional fillers. Surface modification of nanomaterials as well as polymers adds flavor to the dielectric properties of the resulting nanocomposites. Nowadays, three-phase nanocomposites with either combination of fillers...

Synthesis of Two-Dimensional CoS1.097/Nitrogen-Doped Carbon Nanocomposites Using Metal-Organic Framework Nanosheets as Precursors for Supercapacitor Application.

Abstract: Two-dimensional (2D) metal–organic framework (MOF) nanosheets are attracting increasing research interest. Here, for the first time, we report the facile synthesis of 2D porphyrin paddlewheel framework-3 (PPF-3) MOF nanosheets with thickness of ca. 12–43 nm. Through the simultaneous sulfidation and carbonization of PPF-3 MOF nanosheets, we have prepared the 2D nanocomposite of CoS1.097 nanoparticles (NPs) and nitrogen-doped carbon, referred to as CoSNC, in which the CoS1.097 NPs with size of ca. 10 nm are embedded in the nitrogen-doped carbon matrix. As a proof-of-concept application, the obtained 2D CoSNC nanocomposite is used as an electrode material for a supercapacitor, which exhibits a specific capacitance of 360.1 F g–1 at a current density of 1.5 A g–1. Moreover, the composite electrode also shows high rate capability. Its specific capacitance delivered at a current density of 30.0 A g–1 retains 56.8% of the value at 1.5 A g–1.

Review of the recent developments in cellulose nanocomposite processing

Abstract: This review addresses the recent developments of the, processing of cellulose nanocomposites, focusing on the most used techniques, including solution casting, melt-processing of thermoplastic cell ...

High-Performance Epoxy Nanocomposites Reinforced with Three-Dimensional Carbon Nanotube Sponge for Electromagnetic Interference Shielding

Abstract: Light-weight and high-performance electromagnetic interference (EMI)-shielding epoxy nanocomposites are prepared by an infiltration method using a 3D carbon nanotube (CNT) sponge as the 3D reinforcement and conducting framework. The preformed, highly porous, and electrically conducting framework acts as a highway for electron transport and can resist a high external loading to protect the epoxy nanocomposite. Consequently, a remarkable conductivity of 148 S m−1 and an outstanding EMI shielding effectiveness of around 33 dB in the X-band are achieved for the epoxy nanocomposite with 0.66 wt% of CNT sponge, which is higher than that achieved for epoxy nanocomposites with 20 wt% of conventional CNTs. More importantly, the CNT sponge provides a dual advantage over conventional CNTs in its prominent reinforcement and toughening of the epoxy composite. Only 0.66 wt% of CNT sponge significantly increases the flexural and tensile strengths by 102% and 64%, respectively, as compared to those of neat epoxy. Moreover, the nanocomposite shows a 250% increase in tensile toughness and a 97% increase in elongation at break. These results indicate that CNT sponge is an ideal functional component for mechanically strong and high-performance EMI-shielding nanocomposites.

Polymer nanocomposites-A comparison between carbon nanotubes, graphene, and clay as nanofillers

Abstract: Nanofilled polymeric matrices have demonstrated remarkable mechanical, electrical, and thermal properties. In this article we review the processing of carbon nanotube, graphene, and clay montmorillonite platelet as potential nanofillers to form nanocomposites. The various functionalization techniques of modifying the nanofillers to enable interaction with polymers are summarized. The importance of filler dispersion in the polymeric matrix is highlighted. Finally, the challenges and future outlook for nanofilled polymeric composites are presented.

Giant Energy Density and Improved Discharge Efficiency of Solution-Processed Polymer Nanocomposites for Dielectric Energy Storage.

Abstract: Large-aspect-ratio composite nanofibers with interior hierarchical interfaces are employed to break the adverse coupling of electric displacement and breakdown strength in flexible poly(vinylidene fluoride-hexafluoropropylene) nanocomposite films, a small loading of 3 vol% BaTiO3@TiO2 nanofibers gives rise to the highestenergy density (≈31.2 J cm(-3)) ever achieved in polymer nanocomposites dielectrics.

Nanocomposite of carbon nanotubes/silica nanoparticles and their use for adsorption of Pb(II): from surface properties to sorption mechanism

Abstract: This paper demonstrates the synthesis of multi-wall carbon nanotubes and silica nanocomposite (CNT/SiO2). Successful realization of MWCNT/SiO2 nanostructure was observed by scanning electron microscopy, energy dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy and high-resolution transmission electron microscopy studies. The as-prepared nanocomposite was evaluated as an adsorbent to remove lead, Pb(II), from aqueous solutions. The resulting MWCNT/SiO2 manifests propitious adsorption performance (~95%) over silica nanoparticles (~50%) and CNTs (~45%). Lagergren’s pseudo-first order, pseudo-second order and intraparticle diffusion models were used to analyse the kinetic data obtained at different initial Pb(II) concentrations. The adsorption kinetic data were described well by the pseudo-second order model with R2 of 0.99. The activation energy (Ea) of the adsorption process was calculated as 15.8 kJ mol−1. Adsorption data were described well by the Langmuir and Temkin models. Th...

Ce3+-ion-induced visible-light photocatalytic degradation and electrochemical activity of ZnO/CeO2 nanocomposite

Abstract: In this study, pure ZnO, CeO2 and ZnO/CeO2 nanocomposites were synthesized using a thermal decomposition method and subsequently characterized using different standard techniques. High-resolution X-ray photoelectron spectroscopy measurements confirmed the oxidation states and presence of Zn(2+), Ce(4+), Ce(3+) and different bonded oxygen species in the nanocomposites. The prepared pure ZnO and CeO2 as well as the ZnO/CeO2 nanocomposites with various proportions of ZnO and CeO2 were tested for photocatalytic degradation of methyl orange, methylene blue and phenol under visible-light irradiation. The optimized and highly efficient ZnO/CeO2 (90:10) nanocomposite exhibited enhanced photocatalytic degradation performance for the degradation of methyl orange, methylene blue, and phenol as well as industrial textile effluent compared to ZnO, CeO2 and the other investigated nanocomposites. Moreover, the recycling results demonstrate that the ZnO/CeO2 (90:10) nanocomposite exhibited good stability and long-term durability. Furthermore, the prepared ZnO/CeO2 nanocomposites were used for the electrochemical detection of uric acid and ascorbic acid. The ZnO/CeO2 (90:10) nanocomposite also demonstrated the best detection, sensitivity and performance among the investigated materials in this application. These findings suggest that the synthesized ZnO/CeO2 (90:10) nanocomposite could be effectively used in various applications.

Boosting Photocatalytic Hydrogen Production of a Metal-Organic Framework Decorated with Platinum Nanoparticles: The Platinum Location Matters.

Abstract: Improving the efficiency of electron–hole separation and charge-carrier utilization plays a central role in photocatalysis. Herein, Pt nanoparticles of ca. 3 nm are incorporated inside or supported on a representative metal–organic framework (MOF), UiO-66-NH2, denoted as Pt@UiO-66-NH2 and Pt/UiO-66-NH2, respectively, for photocatalytic hydrogen production via water splitting. Compared with the pristine MOF, both Pt-decorated MOF nanocomposites exhibit significantly improved yet distinctly different hydrogen-production activities, highlighting that the photocatalytic efficiency strongly correlates with the Pt location relative to the MOF. The Pt@UiO-66-NH2 greatly shortens the electron-transport distance, which favors the electron–hole separation and thereby yields much higher efficiency than Pt/UiO-66-NH2. The involved mechanism has been further unveiled by means of ultrafast transient absorption and photoluminescence spectroscopy.

Small magnetic Co-doped NiZn ferrite/graphene nanocomposites and their dual-region microwave absorption performance

Abstract: In this study, novel CNZF (Co-doped Ni–Zn ferrite)/GN (graphene) nanocomposites were prepared by using a facile one-pot hydrothermal method. The phase structure, morphology, and magnetic and electromagnetic performance of the nanocomposites were studied by means of modern measurement techniques. Both sides of the GN sheets were densely covered by CNZF nanoparticles. Moreover, the magnetic nanoparticles had a uniform distribution without the presence of significant agglomeration. The electromagnetic performance indicated that the content of GN played a significant role in determining the dielectric behavior and magnetic anisotropy of the carbon materials, which further influenced the impedance matching and attenuation ability of absorbers. The microwave absorption properties showed that the CNZF/GN-10 nanocomposite exhibited dual-region microwave absorption, with two strong reflection loss peaks of −53.5 dB and −58.3 dB at 9.6 GHz and 5.2 GHz, respectively. The effective absorption bandwidths were as wide as 14.8 GHz, with thicknesses in the range of 1.5–6.0 mm. In addition, such dual-region absorption performance was also observed in CNZF/GN nanocomposites with other compositions. The appearance of dual-region absorption and the mechanism of microwave absorption were discussed in detail. It is expected that this CNZF/GN nanocomposite can be used as a new type of an efficient microwave absorber with light weight.

Molybdenum Disulfide/Nitrogen‐Doped Reduced Graphene Oxide Nanocomposite with Enlarged Interlayer Spacing for Electrocatalytic Hydrogen Evolution

Abstract: Facile design of low-cost and highly active catalysts from earth-abundant elements is favorable for the industrial application of water splitting. Here, a simple strategy to synthesize an ultrathin molybdenum disulfide/nitrogen-doped reduced graphene oxide (MoS2/N-RGO-180) nanocomposite with the enlarged interlayer spacing of 9.5 A by a one-step hydrothermal method is reported. The synergistic effects between the layered MoS2 nanosheets and N-doped RGO films contribute to the high activity for hydrogen evolution reaction (HER). MoS2/N-RGO-180 exhibits the excellent catalytic activity with a low onset potential of −5 mV versus reversible hydrogen elelctrode (RHE), a small Tafel slope of 41.3 mV dec−1, a high exchange current density of 7.4 × 10−4 A cm−2, and good stability over 5 000 cycles under acidic conditions. The HER performance of MoS2/N-RGO-180 nanocomposite is superior to the most reported MoS2-based catalysts, especially its onset potential and exchange current density. In this work, a novel and simple method to the preparation of low-cost MoS2-based electrocatalysts with the extraordinary HER performance is presented.

Hierarchical Tubular Structures Composed of Co3O4 Hollow Nanoparticles and Carbon Nanotubes for Lithium Storage

Abstract: Hierarchical tubular structures composed of Co3O4 hollow nanoparticles and carbon nanotubes (CNTs) have been synthesized by an efficient multi-step route. Starting from polymer-cobalt acetate (Co(Ac)2) composite nanofibers, uniform polymer-Co(Ac)2@zeolitic imidazolate framework-67 (ZIF-67) core–shell nanofibers are first synthesized via partial phase transformation with 2-methylimidazole in ethanol. After the selective dissolution of polymer-Co(Ac)2 cores, the resulting ZIF-67 tubular structures can be converted into hierarchical CNTs/Co-carbon hybrids by annealing in Ar/H2 atmosphere. Finally, the hierarchical CNT/Co3O4 microtubes are obtained by a subsequent thermal treatment in air. Impressively, the as-prepared nanocomposite delivers a high reversible capacity of 1281 mAh g−1 at 0.1 A g−1 with exceptional rate capability and long cycle life over 200 cycles as an anode material for lithium-ion batteries.

Facile Fabrication of MoS2-Modified SnO2 Hybrid Nanocomposite for Ultrasensitive Humidity Sensing

Abstract: An ultrasensitive humidity sensor based on molybdenum-disulfide- (MoS2)-modified tin oxide (SnO2) nanocomposite has been demonstrated in this work. The nanostructural, morphological, and compositional properties of an as-prepared MoS2/SnO2 nanocomposite were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), energy dispersive spectrometry (EDS), nitrogen sorption analysis, and Raman spectroscopy, which confirmed its successful preparation and rationality. The sensing characteristics of the MoS2/SnO2 hybrid film device against relative humidity (RH) were investigated at room temperature. The RH sensing results revealed an unprecedented response, ultrafast response/recovery behaviors, and outstanding repeatability. To our knowledge, the sensor response yielded in this work was tens of times higher than that of the existing humidity sensors. Moreover, the MoS2/SnO2 hybrid nanocomposite film sensor exhibited great enhancement in humidity sensi...

1D/2D Carbon Nanomaterial‐Polymer Dielectric Composites with High Permittivity for Power Energy Storage Applications

Abstract: With the development of flexible electronic devices and large-scale energy storage technologies, functional polymer-matrix nanocomposites with high permittivity (high-k) are attracting more attention due to their ease of processing, flexibility, and low cost. The percolation effect is often used to explain the high-k characteristic of polymer composites when the conducting functional fillers are dispersed into polymers, which gives the polymer composite excellent flexibility due to the very low loading of fillers. Carbon nanotubes (CNTs) and graphene nanosheets (GNs), as one-dimensional (1D) and two-dimensional (2D) carbon nanomaterials respectively, have great potential for realizing flexible high-k dielectric nanocomposites. They are becoming more attractive for many fields, owing to their unique and excellent advantages. The progress in dielectric fields by using 1D/2D carbon nanomaterials as functional fillers in polymer composites is introduced, and the methods and mechanisms for improving dielectric properties, breakdown strength and energy storage density of their dielectric nanocomposites are examined. Achieving a uniform dispersion state of carbon nanomaterials and preventing the development of conductive networks in their polymer composites are the two main issues that still need to be solved in dielectric fields for power energy storage. Recent findings, current problems, and future perspectives are summarized.

Thermal exfoliation of hexagonal boron nitride for effective enhancements on thermal stability, flame retardancy and smoke suppression of epoxy resin nanocomposites via sol–gel process

Abstract: The structure of hexagonal boron nitride (h-BN) is similar to that of graphite before functionalization and exfoliation. For applications in polymer nanocomposites, chemical exfoliation is a more economically attractive route to few-layer h-BN nanosheets. A thermal oxidation process of h-BN powder could achieve large scale exfoliation and hydroxylated functionalization, as described in prior literature. In this report, hydroxylated h-BN (BNO) was prepared by heating h-BN under air, and then covalently incorporated into epoxy resin modified with (3-isocyanatopropyl)triethoxysilane to prepare epoxy resin (EP) nanocomposites by sol–gel process. The structure and morphology of BNO were well characterized. BNO was dispersed in the EP matrix with the form of mainly exfoliated and intercalated structures, and formed strong interfacial interaction with the matrix. Thermogravimetric analysis results revealed that BNO significantly improved thermal stability and thermal oxidative resistance of EP nanocomposites at high temperature. The char yield and the temperature at 50 wt% mass loss were increased and the maximum mass loss rate was remarkably reduced. Moreover, the addition of 3 wt% BNO led to extremely high Tg of EP nanocomposite, 42.7 °C higher than that of pure EP, due to improved crosslinking density and confinement effect of BNO sheets on the mobility of polymer networks. Cone calorimeter test results indicated that fire safety properties of EP nanocomposites were also enhanced by the addition of BNO, such as 53.1% reduction in peak heat release rate and 32.6% decrease in total heat release, and decreased release of smoke and toxic gases. The mechanism for enhanced fire retardancy is that thermally stable condensed barrier consisting of h-BN sheets and silicon dioxide for heat and mass transfer protects the matrix from further combustion.

High‐Energy, High‐Rate, Lithium–Sulfur Batteries: Synergetic Effect of Hollow TiO2‐Webbed Carbon Nanotubes and a Dual Functional Carbon‐Paper Interlayer

Abstract: A novel nanocomposite cathode consisting of sulfur and hollow-mesoporous titania (HMT) embedded within carbon nanotubes (CNT), which is designated as S-HMT@CNT, has been obtained by encapsulating elemental sulfur into the pores of hollow-mesoporous, spherical TiO2 particles that are connected via CNT. A carbon-paper interlayer, referred to as dual functional porous carbon wall (DF-PCW), has been obtained by filling the voids in TiO2 spheres with carbon and then etching the TiO2 template with a chemical process. The DF-PCW interlayer provides a medium for scavenging the lithium polysulfides and suppressing them from diffusing to the anode side when it is inserted between the sulfur cathode and the separator. Lithium–sulfur cells fabricated with the thus prepared S-HMT@CNT cathode and the DF-PCW interlayer exhibit superior performance due to the containment of sulfur in TiO2 and improved lithium–ion and electron transports. The Li–S cells display high capacity with excellent capacity retention at rates as high as 1C, 2C, and 5C rates.

Bioinspired, Highly Stretchable, and Conductive Dry Adhesives Based on 1D–2D Hybrid Carbon Nanocomposites for All-in-One ECG Electrodes

Abstract: Here we propose a concept of conductive dry adhesives (CDA) combining a gecko-inspired hierarchical structure and an elastomeric carbon nanocomposite. To complement the poor electrical percolation of 1D carbon nanotube (CNT) networks in an elastomeric matrix at a low filler content (∼1 wt %), a higher dimensional carbon material (i.e., carbon black, nanographite, and graphene nanopowder) is added into the mixture as an aid filler. The co-doped graphene and CNT in the composite show the lowest volume resistance (∼100 ohm·cm) at an optimized filler ratio (1:9, total filler content: 1 wt %) through a synergetic effect in electrical percolation. With an optimized conductive elastomer, gecko-inspired high-aspect-ratio (>3) microstructures over a large area (∼4 in.2) are successfully replicated from intaglio-patterned molds without collapse. The resultant CDA pad shows a high normal adhesion force (∼1.3 N/cm2) even on rough human skin and an excellent cycling property for repeatable use over 30 times without de...

Efficient phosphate sequestration for water purification by unique sandwich-like MXene/magnetic iron oxide nanocomposites.

Abstract: Rationally tailored intercalation for two-dimensional (2D) layered MXene materials has aroused extraordinary enthusiasm for broadening their applications. Herein, a novel sandwiched structural 2D MXene-iron oxide (MXI) material, prepared by selectively exfoliating an Al layer followed by magnetic ferric oxide intercalation, exhibits remarkable applicability to trace phosphate sequestration in the environmental remediation realm. Compared with commercial adsorbents, the resultant MXI nanocomposite exhibits a fast separation in 120 s together with the superior treatment capacities of 2100 kg and 2400 kg per kg in simulated and real phosphate wastewater applications, respectively. Such efficient sequestration is ascribed to the formation of a unique nano-ferric oxide morphology. The ultrafine nano-Fe2O3 particles can intercalate into the interior layers of MXene, widening the layer distance, and stimulating the available overlapping activated layers; while the efficient phosphate removal can be achieved by the strong complexation onto the embedded magnetic nano-Fe3O4 with a unique sandwich-structure as well as the stimulated Ti-O terminal within MXene. Apart from the fact that this approach suggests a complementary means for environmental remediation, it opens a new trajectory to achieve the functionalization of MXene.

High performance polymer nanocomposites for additive manufacturing applications

Abstract: Additive manufacturing (or 3D printing) involves the process of fabricating a part by layer-by-layer assembly of materials with processes such as extrusion, binding, melting, and photopolymerization. It is transforming how we assemble our prototypes and, in the future, manufacture our products. There have been a number of materials that can be utilized for this technology, however, high performance polymer nanocomposites are a very important class of material that is just recently being used in additive manufacturing. High performance polymer is a group of polymer materials that are known to retain its desirable mechanical, thermal, and chemical properties when subjected to harsh environment such as high temperature, high pressure, and corrosive chemicals. When mixed with nanofillers such as carbon nanotube, nanoclay, and graphene, these polymers can have improved mechanical properties and sometimes acquire properties that were not present initially like thermal and electrical conductivity. This review article aims to summarize available additive manufacturing techniques, high performance polymers and nanofillers available, and research efforts on its use for additive manufacturing.

A novel Co/TiO2 nanocomposite derived from a metal–organic framework: synthesis and efficient microwave absorption

Abstract: To overcome the shortcomings (poor impedance mismatching and weak electromagnetic wave attenuation) of the Co nanoparticles embedded into nanoporous carbon (Co@NPC) derived from the thermal decomposition of zeolitic imidazolate framework-67 (ZIF-67), two coated titanium oxide (TiO2) routes are designed to prepare core–shell Co@NPC@TiO2 and multi-interfaced yolk–shell C–ZIF-67@TiO2 (obtained from the thermal decomposition of ZIF-67@TiO2) structures. The permittivity and permeability of C–ZIF-67@TiO2 significantly depend on the thickness of the TiO2 shell in ZIF-67@TiO2, and the thickness of the TiO2 shell in the as-obtained samples can be easily controlled via changing the addition content of tetrabutyl titanate in the hydrolyzation process. The as-prepared samples have remarkable absorbing characteristics in wide frequency bands from 2–18 GHz with thicknesses of 1.0–5.0 mm. 50 wt% of the C–ZIF-67@TiO2-2 (the addition amount of tetrabutyl titanate is 2 mL) nanocomposite filled within paraffin shows a maximum reflection loss (RL) of −51.7 dB at an absorbing thickness of 1.65 mm, meanwhile, for the Co@NPC@TiO2-1.2 (the addition amount of tetrabutyl titanate is 1.2 mL) nanocomposite, a maximum RL can be achieved of −31.7 dB at 1.5 mm. This study provides a good reference for the future preparation of other carbon-based lightweight microwave absorbing materials derived from metal organic frameworks.

High-Performance All-Solid-State Lithium–Sulfur Battery Enabled by a Mixed-Conductive Li2S Nanocomposite

Abstract: All-solid-state lithium–sulfur batteries (ASSLSBs) using highly conductive sulfide-based solid electrolytes suffer from low sulfur utilization, poor cycle life, and low rate performance due to the huge volume change of the electrode and the poor electronic and ionic conductivities of S and Li2S. The most promising approach to mitigate these challenges lies in the fabrication of a sulfur nanocomposite electrode consisting of a homogeneous distribution of nanosized active material, solid electrolyte, and carbon. Here, we reported a novel bottom-up method to synthesize such a nanocomposite by dissolving Li2S as the active material, polyvinylpyrrolidone (PVP) as the carbon precursor, and Li6PS5Cl as the solid electrolyte in ethanol, followed by a coprecipitation and high-temperature carbonization process. Li2S active material and Li6PS5Cl solid electrolyte with a particle size of ∼4 nm were uniformly confined in a nanoscale carbon matrix. The homogeneous nanocomposite electrode consisting of different nanopar...