Intercalation Structure Research Articles

Non–ferroelectric intercalation structure based on Aurivillius phase Bi4Ti3O12: A research arena to achieve high energy storage performance

High density energy capacity is the benchmark of electronic industry, and its improvement is on the way. Here, the BaCaBi4Ti5O18 films present high efficient energy storage trait, which is originated from ferroelectric/non–ferroelectric intercalation structure. The emergent of large gradient elastic energy in ferroelectric/non–ferroelectric intercalation structure not only crushes the ferroelectric domains, but also modulates space charges accumulation. Both factors contribute to the high polarization and intense breakdown strength. The contrast experiments were conducted by single ferroelectric intercalated structure Bi5Ti3FeO15 films, which show almost non ferroelectric energy storage behavior. The finite element simulations are consistent with the experimental evidences. The present results may facilitate a way for structural design of Aurivillius family, which is capable of acting as remarkable energy storage tasks.

Effect of Copper and Titanium-Exchanged Montmorillonite Nanostructures on the Packaging Performance of Chitosan/Poly-Vinyl-Alcohol-Based Active Packaging Nanocomposite Films

In this study, CuMt and TiMt montmorillonites were produced via an ion-exchange process with Cu+ and Ti4+ ions. These nanostructured materials were characterized with X-ray diffraction (XRD) and fourier transform infrared spectroscopy (FTIR) measurements and added as nanoreinforcements and active agents in chitosan (CS)/poly-vinyl-alcohol (PVOH)-based packaging films. The developed films were characterized by XRD and FTIR measurements. The antimicrobial, tensile, and oxygen/water-barrier measurements for the evaluation of the packaging performance were carried out to the obtained CS/PVOH/CuMt and CS/PVOH/TiMt films. The results of this study indicated that CS/PVOH/CuMt film is a stronger intercalated nanocomposite structure compared to the CS/PVOH/TiMt film. This fact reflected higher tensile strength and water/oxygen-barrier properties. The antibacterial activity of these films was tested against four food pathogenic bacteria: Escherichia coli, Staphylococcus aureus, Salmonella enterica and Listeria monocytogenes. Results showed that in most cases, the antibacterial activity was generated by the CuMt and TiMt nanostructures. Thus, both CS/PVOH/CuMt and CS/PVOH/TiMt films are nanocomposite candidates with very good perspectives for future applications on food edible active packaging.

Phosphate group-mediated carriers transfer and energy band over carbon nitride for efficient photocatalytic H2 production and removal of rhodamine B

The development of effective methods that simultaneously regulate energy bands and electron transfer to realize high photocatalytic performance of graphitic carbon nitride (g-C3N4) remains a major challenge. Herein, we developed a novel strategy to construct a phosphate-group-intercalated g-C3N4 nanosheet photocatalyst that is driven by visible light. A series of characterizations confirmed that phosphate groups were inserted between the g-C3N4 layers and formed a vertical channel. A porous ultrathin nanosheet structure was formed. The synergistic effect of the phosphate-group intercalation and porous ultrathin nanosheet structure endowed this material with controllable electronic structures and upshifted the conduction bands, while facilitating photogenerated charge transfer and providing numerous active reactive sites. As a result, the g-C3N4 intercalated with phosphate groups photocatalyst exhibited high photocatalytic activity for H2 evolution and degradation of a coloured dye rhodamine B (RhB) under visible light. The maximum H2 production rate and degradation rate constant of the phosphate-group-intercalated g-C3N4 nanosheets (CNP-5) were 17-fold and 6-fold higher than those of primal g-C3N4, respectively. This study provides new insights for the incorporating atomic groups with modification effects and represents a giant leap in the construction of two-dimensional (2D) materials.

Preparation and electrochemical properties of MXene based conductive composites for food contamination detection

MXene has unique intercalation structure, excellent interlayer spacing and excellent biocompatibility. It is considered as an excellent nano material carrier and can be used as a good adsorbent in the detection of food pollutants. In this study, a large number of experimental materials and reagents were selected to prepare Co3O4 / MXene composites by in-situ growth of Co3O4 nanoparticles on MXene support by impregnation pyrolysis. The composite retained the original accordion like intercalation structure. The size and number of Co3O4 particles on the surface of MXene and in the intercalation increased with the increase of loading, showing regular order. The prepared composite has abundant lithium intercalation active sites, fast electron and ion transport channels, good rate performance and energy density at high current density, showing excellent electrochemical performance.

Energetics, Interlayer Molecular Structures, and Hydration Mechanisms of Dimethyl Sulfoxide (DMSO)-Kaolinite Nanoclay Guest-Host Interactions.

Two-dimensional (2D) kaolinite nanoclay is an important natural mineral with promising application potential, especially tuned with organic intercalates. However, thus far, the organics-kaolinite guest-host interactions, the atomic scale structures of organic intercalates under confinement, and molecular level mechanisms of hydration are rarely systematically explored using both experimental and computational methodologies. We integrated density functional theory with dispersion scheme (DFT-D) with various experimental methods to investigate the intercalation of dimethyl sulfoxide (DMSO) in kaolinite with and without hydration. The kinetic, thermodynamic, and structural impacts of hydration were highlighted. In short, water molecules significantly promote intercalation of DMSO into kaolinite because of favorable intercalation energy, which is enabled by effective hydrogen bonding at the guest species (DMSO and water)-kaolinite interfaces.

Facile Synthesis of Graphene with Fast Ion/Electron Channels for High-Performance Symmetric Lithium-Ion Capacitors.

With the battery-type anode and capacitor-type cathode, lithium-ion capacitors (LICs) are expected to exhibit both high energy and high power density but suffer from the mismatch of the electrode reaction kinetics and capacity. Herein, to alleviate the mismatch between the two electrodes and synergistically enhance the energy/power density, we design a method of microwave irradiation reduction to prepare graphene-based electrode material (MRPG/CNT) with fast ion/electron pathway. The three-dimensional structure of CNT intercalation to graphene inhibits the restacking of graphene sheets and improves the conductivity of the electrode material, resulting a rapid ion and electron diffusion channel. Due to its specific properties, MRPG/CNT materials can be used as both anode and cathode electrodes of LICs at the same time. As anode, MRPG/CNT shows a high capacity of 1200 mAh g-1 as well as high rate performance. As cathode, MRPG/CNT displays a high capacity of 108 mAh g-1 and the capacity retention of 100% after 8000 cycles. Coupling the prelithiated MRPG/CNT anode with MRPG/CNT cathode gives a full-graphene-based symmetric LIC, which achieves a high energy density of 232.6 Wh kg-1 at 226.0 W kg-1, 111.2 Wh kg-1 at the ultrahigh power density of 45.2 kW kg-1, and superior capacity retention of 86% after 5000 cycles. The structure design of this electrode provides a new strategy for alleviating the mismatch of LIC electrodes and constructing high-performance symmetrical LICs.

Energy barriers for Dy and H penetrating graphene on 6H-SiC(0001) and freestanding bilayer graphene from first-principles calculations

Currently, intercalation of foreign guest atoms into two-dimensional (2D) layered van der Waals materials is an active research area motivated in part by the development of next-generation energy-storage technologies and optoelectronic devices. One such extensively studied 2D material is the graphene-on-SiC system. To realize and control the desired intercalated structures, it is fundamentally important to understand the kinetic process of intercalation. For the intercalation of a guest atom into graphene layers on SiC substrate, a critical kinetic parameter is the energy barrier of a guest atom penetrating the perfect graphene top layer into the gallery under it. However, accurate theoretical calculations for such penetration barriers are unavailable in literature. From our first-principles density functional theory calculations, we obtain the global energy barriers of 3.47 and 1.80 eV for single Dy and H atoms penetrating the graphene top layer on a graphene buffer layer supported by a Si-terminated 6H-SiC(0001) substrate, respectively. For comparison as well as for examining the lateral strain effects, we also obtain the global barriers of 5.05 and 1.50 eV for single Dy and H atoms penetrating freestanding bilayer graphene with a tensile strain of about 8.8% to match our model for supported graphene, as well as the global barriers of 7.21 and 4.18 eV for penetrating unstrained freestanding bilayer graphene, respectively. From corresponding minimum energy paths with multiple energy minima and saddle points, we can also obtain various local energy barriers and the global backward barrier from the graphene gallery back to the top surface.

Nickel-doped monoclinic WO3 as high performance anode material for rechargeable lithium ion battery

• Monoclinic WO 3 nanoparticles are successfully doped by 10 wt% of Nickel element. • The N10mWO 3 delivers 1st /2nd discharge capacities of 1287/1012 mAh g −1 at 100 mA g −1 . • The N10mWO 3 exhibits the capacity retention of 79.60% at 100 mA g −1 after 500 cycles. • The N10mWO 3 shows high rate capability, 650.2 mAh g −1 even at 1000 mA g −1 . The anode materials are one of the critical components in rechargeable lithium ion batteries (LIBs). The monoclinic tungsten trioxide (mWO 3 ) is introduced as interesting anode electrode for LIBs due to its good structure for intercalation and de-intercalation of lithium ions, high abundance and various oxidation state of tungsten and etc. In this study, we prepare and investigate the effect of various amounts of nickel dopant on characteristics and electrochemical properties of the mWO 3 as the anode electrode in a rechargeable LIB. The experimental investigations confirm that the number of nickel atoms has a remarkable effect on controlling spherical particle diameter, crystallite size, and electrochemical properties of mWO 3 . The electrochemical results demonstrate that the 10 wt% nickel dopant leads to make the highest improvements for electrochemical behaviors of mWO 3 . The sample exhibits higher 1 st /2 nd electrochemical capacities (1287/1012 mAh g −1 at 100 mA g −1 ), good cycle life (capacity retention of 79.60% after 500 cycles at 100 mA g −1 ), and better rate capability (650.2 mAh g −1 even at 1000 mA g −1 ) among un-doped and doped mWO 3 samples, including 5 and 20 wt% nickel atoms. These improvements can be related to the spherical morphology of nanoparticles and high electrical conductivity making by nickel dopant, which is beneficial to enhance lithium-ion diffusion and electron transfer in the monoclinic structure of WO 3 . The anode electrode reported here exhibits excellent properties in LIBs for various energy storage applications..

Study on the Preparation of Zn‐Al‐LDHs by Different Reaction Methods with Ion Exchange Resin

AbstractZn‐Al layered double hydroxides (Zn‐Al‐LDHs) were successfully prepared with ion exchange resin and mixed hydroxide by pneumatic stirring, constant temperature oscillation, magnetic stirring and hydrothermal reaction methods. The products were characterized by SEM, EDS, XRD, FT‐IR and TG‐DSC. The advantages and disadvantages of various preparation methods were compared systematically. On the basis of the unique internal structure of ion exchange resin, the resin could effectively control the rate of product generation, and ensure the formation of LDHs slowly and evenly in the whole solution, so that the product morphology was more uniform and dispersed, and the product could be used directly without washing. SEM and XRD results show that the single constant temperature oscillation method and magnetic stirring method could obtain the products with better micromorphology than the pneumatic stirring method, presenting a clear hexagonal sheet structure. At the same time, the two methods can obtain nanoscale Zn‐Al‐LDHs with better crystal structure and higher purity. FT‐IR and TG‐DSC characterization further confirmed the composition of the product and the carbonate intercalation structure of the hydrotalcite.

Study on thermal and mechanical behaviors of polypropylene grade 552R/Cloisite 15A nanocomposites suitable for yarn applications

The investigation of polypropylene (PP)/clay nanocomposites has received considerable scientific and technological attention during the last decades due to their good mechanical and barrier properties. In the present article, the effects of adding Cloisite15A (C15A) nanoclay in polypropylene (PP) were investigated. PP nanocomposites were prepared by a direct melt mixing method. For better dispersion of C15A, 30 wt% of nanoclay masterbatch was first prepared by melt mixing of PP matrix and acrylic acid grafted PP oligomer (PP- g-AA) in a compounder, before being used to produce nanocomposites with 2 and 5 wt% of C15A. The aim of this work was to used nanoclay filled nanocomposites with suitable properties for cable application like good flame-retardant property; improve dye-ability and resilience of polypropylene. The XRD results indicated an intercalated layer structure for nanocomposites, The SEM examination showed satisfactory dispersion of nanoclay in 2 wt% of C15A and some degree of agglomeration in 5 wt% of C15A. DSC analysis indicated that C15A acts as a nucleating agent and increases crystallinity in the nanocomposite. TGA showed with increasing nanoclay, heat resistance was improved and degradation temperatures increased. Limiting oxygen index (LOI) tests showed increased flame retardancy from 25% for neat polypropylene t0 32.2% for nanocomposites of 5 wt% of C15A. The tensile modulus was improved from 423 MPa for neat polypropylene to 474 MPa for nanocomposites with 5 wt% of C15A.This result indicates that increasing C15A content had a suitable effect on the tensile properties. Melt spinning investigation on low oriented yarn (LOY), draw textured yarn (DTY), and fully drawn yarn (FDY) of 2 wt% C15A nanocomposite showed a reduction of linear density for FDY and an increase of the shrinkage. Furthermore, the obtained results for the improvement of dye-ability and compression resilience showed that PP/C15A is appropriate for textile products.

Self-healing properties of nano-montmorillonite-enhanced asphalt binders from the perspective of energetics and morphology

Nano montmorillonite (MMT) is widely used as a modifier to improve asphalt pavements' performance. This paper's main objective was to investigate the effect of nano-montmorillonite on the self-healing properties of asphalt, which was analysed in terms of energy theory, molecular content composition, and microstructure. The healing index based on time-scan tests was used to characterise the base asphalt and styrene–butadiene–styrene (SBS) asphalt binders. The healing master curve was constructed considering the influence of healing time and damage level, and the composite healing index was calculated. The asphalt binder and aggregate's contact angles were measured using the solid drop method, and thermodynamic parameters were calculated based on surface free energy theory. The effects of MMT on healing properties were investigated by gel permeation chromatography (GPC) and scanning electron microscopy (SEM) in terms of changes in molecular weight composition and microstructure. The results showed that MMT enhanced the asphalt binder's cohesive energy and increased the adhesion energy to the aggregate, which in turn improved the self-healing ability of microcracks. The intercalation structure restricted small molecules' movement and promoted the aggregation of large molecules, thus forming a micron-scale laminar rough structure that enhanced the intermolecular forces and improved the healing ability. In addition, MMT had a more significant healing effect on the base asphalt binder but formed a more stable system with the SBS asphalt binder, giving it better healing potential.

Investigating the Effectiveness of Nano-Montmorillonite on Asphalt Binder from Rheological, Thermodynamics, and Chemical Perspectives

In this research, the feasibility of using nano-montmorillonite (MMT) in asphalt binders was investigated in terms of rheological properties, thermomechanical properties, and chemical structure composition. Different doses of MMT were added to the base asphalt and styrene–butadiene–styrene (SBS) asphalt as test subjects. The effect of nanomaterials on the high-temperature resistance of asphalt binders to permanent deformation was analyzed from dynamic mechanical rheology using the multiple stress creep recovery (MSCR) test. The sessile drop method test based on surface free energy (SFE) theory was employed and thermodynamic parameters such as surface free energy, cohesive work, and adhesion work were calculated to analysis the change in energy of the asphalt binder. In addition, changes in the chemical structure and composition of the asphalt binder were examined by Fourier transform infrared (FTIR) and gel permeation chromatography (GPC) tests. The results showed that MMT can effectively enhance the high-temperature elastic recovery and plastic deformation resistance of the asphalt binder. The intercalation structure produced in the asphalt binder enhanced the overall cohesive power and adhesion to the aggregate. The anchoring effect of the intercalation structure resulted in an increase in the macromolecular weight of the binder was demonstrated, indicating that MMT enhanced the overall intermolecular forces of the binder. In addition, the molecular crystal structure was characterized by characteristic functional groups in the infrared spectra, while demonstrating that no chemical reaction occurs during the modification of the binder by the nanomaterials.

Investigation of the anisotropic thermal properties of the cuboid-like Ca(NO3)2-NaNO3/EG composite

Molten salts/expanded graphite (EG) composite phase change materials (PCMs) could have an anisotropic structure due to the intercalation structure of EG, which may lead to anisotropic thermal properties of the composite. In this study, the anisotropic thermal properties of the cuboid-like Ca(NO3)2-NaNO3/EG composite were investigated. The effects of bulk density and temperature on the anisotropic thermal conductivities were studied, and suitable models for prediction of the anisotropic thermal conductivities were analyzed and developed. The results showed that a layer-by-layer structure assembled by EG microsheets with the deposition of salt particles was formed. When the compressing pressure was 4 MPa, the composite showed an isotropic thermal conductivity, while the composites became more and more anisotropic with the increase of compressing pressure. At the room temperature, the axial thermal conductivity increased from 4.016 to 7.694 W/(m K), and the radial thermal conductivity increased from 4.040 to 5.645 W/(m K), when the compressing pressure was increased from 4 to 20 MPa. Contrarily, the working temperature showed little effect on the thermal conductivities. Finally, it was shown that the Maxwell-Eucken model and the modified Parallel model proposed in this work could be used to predict the axial and radial thermal conductivities of the Ca(NO3)2-NaNO3/EG composite, respectively.

Recent Advances in Constructing Interfacial Active Catalysts Based on Layered Double Hydroxides and Their Catalytic Mechanisms

The interaction between the metal and the support of supported metal catalysts, which are widely used in industry, is the primary focus of the study of such catalysts. With the developing understanding of the metal–support interaction, the intrinsic factor that influences the catalytic performance has been determined to be the structure of interfacial sites. Layered double hydroxides (LDHs, a class of two-dimensional layered anion clay) possess several unique characteristics, such as the following: (1) tunable elemental component, homogeneous distribution of metal cations. (2) anchoring effect. (3) multiple layered structure for exfoliation or intercalation and special memory effect; and (4) internal/external confinement effects during topological transformation. Taking LDHs and their derivatives as precursors or supports shows superior advantages in designing interfacial active catalysts with tunable properties. Therefore, this review is mainly focused on constructing interfacial active catalysts by LDHs and revealing the interfacial effects (including electronic, geometric, and bifunctional effects) on the catalytic performance that will provide new perspectives and approaches for the development of heterogeneous catalysis.

Phase transformation and dielectric properties of polyvinylidene fluoride/organic‐montmorillonite nanocomposites fabricated under elongational flow field

AbstractCompounding montmorillonite (MMT) with polymorphic polyvinylidene fluoride (PVDF) by melt intercalation method can induce the crystal phase transformation of PVDF, which is of great significance to obtain the electroactive PVDF. In this research, PVDF/Organic‐Montmorillonite (OMMT) nanocomposites were prepared by a novel vane mixer, which was dominated by the elongational flow field in the whole plasticizing. The dispersion of OMMT, the crystal phase transformation of PVDF, and the resulting properties of nanocomposites were experimentally studied. The results of TEM and WAXD evidenced that homogeneous dispersion and desirable intercalation structure of OMMT were formed in the PVDF matrix under the effect of the elongational flow field. WAXD, FTIR, and DSC tests demonstrated that large amounts of β‐phase of PVDF was formed due to the introduction of OMMT. The intercalation structure of OMMT and the crystal transformation of PVDF increased the dielectric constant and piezoelectric properties of nanocomposites, while the dielectric loss still maintained at a very low level. Finally, the effect of unique ''double‐layer peeling'' mechanism of OMMT on the properties of nanocomposites was discussed.

Bottom-up approach to quasi-monolayer black phosphorus advancing photocatalytic H2 evolution

• A mild bottom-up approach is developed to prepare quasi-monolayer black phosphorus (BP). • Linear diamine-induced “dissolution-crystallization” mechanism via polyphosphide clusters is proposed. • Quasi-monolayer eda-BP exhibits superior ambient stability and photocatalytic H 2 evolution activity. A mild bottom-up approach is developed to prepare quasi-monolayer black phosphorus (BP) from precursor red phosphorus. Linear diamine-induced “dissolution-crystallization” mechanism via polyphosphide clusters is proposed to account for the phosphorus phase transition in solution. For the first time, the application of quasi-monolayer BPs in photocatalytic H 2 evolution is demonstrated. Particularly, ethylenediamine-intercalated quasi-monolayer BP (eda-BP) exhibits 57.2-folds enhancement in photocatalytic H 2 evolution activity than pure BP. The greatly improved photocatalytic performance is ascribed to the optimized bandgap with stronger redox capacity and significantly suppressed photogenerated charges recombination due to strong electron transfer from eda to BP layers. Additionally, the unique intercalation structure endows the quasi-monolayer eda-BP with improved stability. This bottom-up intercalation strategy provides a new opportunity to advance the photocatalytic H 2 evolution activity of BP and offers extendable availability for other 2D photocatalyst materials.

Studies the effect of halloysite nanotubes on the mechanical and hot air ageing properties of nitrile-polyvinyl chloride rubber nano-composites

In this work the effect of halloysite nanotubes (HNT) on the mechanical properties and thermo-oxidative ageing behaviour of Nitrile-Polyvinyl chloride rubber (NBR/PVC) nano-composites is investigated. NBR/PVC nano-composites containing 2, 4, and 6 phr of HNT were prepared by melt-blending on a twin roll mill. X-ray diffraction and Field emission scanning electron microscopy studies revealed formation of limited intercalated structures in NBR/PVC matrix. Fourier transform infrared spectroscopy studies confirmed the formation of hydrogen bonding between NBR/PVC and HNT. Improved interaction between NBR/PVC and HNT increased the tensile strength, elongation at break and tensile modulus by 34%, 22%, and 23% respectively and improved the hardness and compression set. Hot air ageing tests revealed that all the NBR/PVC nano composites demonstrated excellent retention of properties compared with that of conventional composites.

Dual-Anchoring Intercalation Structure and Enhanced Bioactivity of Poly(vinyl alcohol)/Graphene Oxide–Hydroxyapatite Nanocomposite Hydrogels as Artificial Cartilage Replacement

Through the dual-anchoring effect, hydroxyapatite (HA) molecules were intercalated into graphene oxide (GO) layers to form a GO–PEG–HA hybrid, and PVA/GO–PEG–HA nanocomposite hydrogels were prepare...

Thermoelectric and Thermal Properties of a (GeTe)2/Sb2Te3 Interfacial Phase‐Change Memory Device

The thermoelectric and thermal properties of an interfacial phase‐change memory (iPCM) device, in which the resistive switching layer (RSL) is the (GeTe)2/Sb2Te3 superlattice, are investigated. To clarify the effects of intralayer exchange of the GeTe layer and the van der Waals (vdW) gap in the superlattice, a device model consisting of a 10 nm‐scale RSL connected to W(111) electrodes is focused. The two (GeTe)2/Sb2Te3 superlattice structures and one intercalation structure of GeTe in Sb2Te3, which are called inverted Petrov (IP), Ferro (FR), and Kooi–De Hosson (KH) structures, are examined. The calculated thermoelectric properties suggest that doping or charge trapping can enhance the difference in the thermoelectric properties and electric resistance contrast due to a phase change. Phonon thermal transport is almost ballistic for all three structural phases, whereas the KH structure shows the lowest thermal conductance and a large effect of phonon–phonon scattering. The theoretical calculations show that thermal and thermoelectric properties could be useful for identifying local structural change and atomic rearrangement.

Flexible and lightweight Ti3C2Tx MXene/Fe3O4@PANI composite films for high-performance electromagnetic interference shielding

Ti3C2Tx MXene has been explored as an efficient electromagnetic interference (EMI) shielding material because of its high electrical conductivity, large specific surface area, rich surface defects, and abundant functional groups. Herein, core-shell Fe3O4@PANI composites were prepared, followed by the preparation of a flexible and lightweight Ti3C2Tx/Fe3O4@PANI composite film with sandwich intercalation structure by vacuum-assisted filtration, using Ti3C2Tx MXene as a matrix material. The ultrathin composite film with a Ti3C2Tx nanosheets to Fe3O4@PANI weight ratio of 12:5 reached a maximum EMI shielding effectiveness (SE) value of 58.8 dB at a thickness of only 12.1 μm. This is much higher than the SE of pure conductive Ti3C2Tx films of the same thickness. After adjusting the film thickness by increasing the concentration of Ti3C2Tx, an SE of 62 dB was achieved at a thickness of 16.7 μm. The ultrathin Ti3C2Tx/Fe3O4@PANI films exhibit potential for application in packaging, wearable electronic equipment, and military fields. Moreover, they provide insight into the preparation of lightweight and progressive electromagnetic shielding materials.