Interlayer Force Research Articles

From spent graphite to recycle graphite anode for high-performance lithium ion batteries and sodium ion batteries

Nowadays, recycling cathode materials form spent lithium ion batteries (LIBs) has attracted widespread attentions in order to recover highly-valuable metal elements. However, recycling graphite materials is usually discarded because of the low added value and rigorous separation steps. In this study, we investigate the possibility of reusing spent graphite as anode material for LIBs and SIBs after reconstruction process. Benefiting form the structural reconstruction process, which can enhance the interlayer force and reduce the interlayer lattice distance of graphite, lead to the reconstructed graphite with improved and stable layered structure. When used as anode materials for LIBs, the reconstructed graphite exhibits outstanding electrochemical performance. As a result, the reconstructed graphite can deliver high capacity of 427.9 mAh g−1 after 200 cycles at 0.5 C, and also display a outstanding rate capability (a capacity of 114.9 mAh g−1 is achieved at 3 C). Furthermore, the acid-treated graphite can be directly used as anode material for SIBs, which exhibit high reversible capacity of 127 mAh g−1 at 50 mA g−1, and also exhibits excellent long cycle life (a reversible capacity of 106.8 mAh g−1 is achieved after 500 cycles at 2000 mA g−1 with high capacity retention of 90.98%).

Analysis of Nonlinear Vibrations of Slightly Curved Tripled-Walled Carbon Nanotubes Resting on Elastic Foundations in a Magneto-Thermal Environment

In this work, nonlocal elasticity theory is applied to analyze nonlinear free vibrations of slightly curved multi-walled carbon nanotubes resting on nonlinear Winkler and Pasternak foundations in a thermal and magnetic environment. With the aid of Galerkin decomposition method, the systems of nonlinear partial differential equations are transformed into systems of nonlinear ordinary differential equations which are solved using homotopy perturbation method. The influences of elastic foundations, magnetic field, temperature rise, interlayer forces, small scale parameter and boundary conditions on the frequency ratio are investigated. It is observed form the results that the frequency ratio for all boundary conditions decreases as the number of walls increases. Also, it is established that the frequency ratio is highest for clamped-simple supported and lowest for clamped-clamped supported. Further investigations on the controlling parameters of the phenomena reveal that the frequency ratio decreases with increase in the value of spring constant (k1) temperature and magnetic field strength. It is hoped that this work will enhance the applications of carbon nanotubes in structural, electrical, mechanical and biological applications especially in a thermal and magnetic environment.

Synergy between van der waals heterojunction and vacancy in ZnIn2S4/g-C3N4 2D/2D photocatalysts for enhanced photocatalytic hydrogen evolution

Fabricating 2D/2D heterojunction with vacancy is more favorable to the spatial separation and transfer of charge owing to the matching of unique 2D structure and vacancy engineering, but the regulation and observation of interlayer forces and electronic structure is a challenging task for synthesizing heterojunction photocatalyst and studying the photocatalytic hydrogen evolution mechanism. Herein, an original 2D/2D ZnIn2S4/g-C3N4 Van der Waals heterojunction with S vacancies (ZIS-S/CN VDW) photocatalyst are firstly engineered. The optimized 30ZIS-S/g-C3N4 has the highest H2 evolution rate of 6095.1 μmol h−1 g−1, which is primarily attributed to the fact that 2D/2D VDW heterojunction possesses larger contact area and strong electronic interaction to stimulate charge kinetics, and the vacancy engineering can enhance light absorption by regulating the electronic band structure and act as effective active sites for capturing electrons. This work not only enriches 2D/2D heterojunction photocatalytic system based on g-C3N4, but also provides alternative proposal for engineering 2D/2D heterojunction photocatalyst with satisfactory performance.

Hydrogen-Bond-Assisted Reinforcement of Interlayer Connections in Zn2BO3X·H2O (X = Cl, Br): Two UV Nonlinear Optical Crystals with KBBF-Type Structure.

Two novel zinc borate halides named Zn2BO3X·H2O (X = Cl, Br) were discovered through hydrothermal techniques. Both compounds are isomorphic and feature the layered structure similar to that of KBBF, consisting of the infinite planar [Zn2BO3X·OH2] (X = Cl, Br) layers. Compared with the weak ionic bond between adjacent layers in KBBF, the strong interaction of hydrogen bonds between layers in Zn2BO3X·H2O (X = Cl, Br) effectively enhances the interlayer force, contributing to eliminating the layering growth tendency. Optical measurements on these two NLO crystals revealed that they have a broad wavelength transparency window and a moderate NLO coefficient. Moreover, the theoretical calculations revealed that the linear and NLO properties primarily depended on the [BO3] and [ZnO3Cl/Br] groups in both crystals.

Controlled WS2 crystallinity effectively dominating sodium storage performance

WS2 exhibits tremendous potentials for Na-ions storage owing to high capacity (433 mAh g−1). Nevertheless, WS2 layered structure is often exfoliated with rapid capacity decay and sluggish reaction kinetics. In this work, WS2 nanosheets with different crystallinities are controlled by different synthesis methods. The high crystallinity WS2 exhibits high degree of interlayer order and strong interlayer force. It exhibits superior electrochemical properties, at the current density of 200 mA g−1 after 300 cycles with reversible capacity of 471 mAh g−1. Even at 5.0 A g−1, the capacities can still arrive at 240 mAh g−1 after 250 cycles, exhibiting stable cycling performance. Further electrochemical research finds that the high degree of interlayer order of layered WS2 structure can perform highly conducive Na+ insertion/extraction with greatly improved contribution of intercalation capacity. Moreover, the strong interlayer force can effectively restrain the exfoliating of the WS2 nanosheets, guaranteeing the stability of the structure. Combining the above result reveals that controlling the order and force of the interlayer is an effective way to enhance the electrochemical properties of WS2 as SIBs anode materials. This work can provide new insight for inhibiting the exfoliation of layered compounds to pursue excellent electrochemical performance in Na-ion storage systems.

Influence of elastic property on the friction between atomic force microscope tips and 2D materials

The relationship between the elastic property of solid materials and friction has been discussed and studied by theoretical calculation and analysis. In the present work, we perform an experimental study concerning this relationship. Atomic force microscope (AFM) scanning of four different transition metal dichalcogenides is conducted under different experimental conditions. It is found that materials with smaller vertical interlayer force constant, which also means smaller elasticity modulus, have larger friction. We attribute this phenomenon to larger elastic deformation in softer materials, which results in a larger obstacle to the motion of AFM tips.

Applications of Two-Dimensional Nanomaterials in Breast Cancer Theranostics.

Breast cancer is the leading cause of cancer-related mortality among women. Early stage diagnosis and treatment of this cancer are crucial to patients' survival. In addition, it is important to avoid severe side effects during the process of conventional treatments (surgery, chemotherapy, hormonal therapy, and targeted therapy) and increase the patients' quality of life. Over the past decade, nanomaterials of all kinds have shown excellent prospects in different aspects of oncology. Among them, two-dimensional (2D) nanomaterials are unique due to their physical and chemical properties. The functional variability of 2D nanomaterials stems from their large specific surface area as well as the diversity of composition, electronic configurations, interlayer forces, surface functionalities, and charges. In this review, the current status of 2D nanomaterials in breast cancer diagnosis and therapy is reviewed. In this respect, sensing of the tumor biomarkers, imaging, therapy, and theranostics are discussed. The ever-growing 2D nanomaterials are building blocks for the development of a myriad of nanotheranostics. Accordingly, there is the possibility to explore yet novel properties, biological effects, and oncological applications.

Toward Nanomechanical Models of Liquid-Phase Exfoliation of Layered 2D Nanomaterials: Analysis of a π − peel Model

In liquid-phase exfoliation for the production of 2D nanomaterials fluid forces are used to gently overcome adhesive interlayer forces, leading to single- or few-layer 2D nanomaterials. Predicting accurately the critical fluid shear rate for exfoliation is a crucial challenge. By combining notions of fluid mechanics and fracture mechanics, we analyse a mathematical model of exfoliation, focusing on the $\pi$-peel regime in which bending forces are much smaller than the applied hydrodynamic forces. We find that in this regime the shear rate is approximately proportional to the adhesion energy, independent of the bending rigidity of the exfoliated sheet, and inversely proportional to the size $a$ of a (assumed pre-existing) material flaw. The model appears to give values comparable to those obtained in wet ball milling, but to overestimate the shear rate values reported for turbulent exfoliation (by rotor mixing or microfluidization). We suggest that for turbulent exfoliation a "cleavage model" may be more appropriate, as it gives a stronger dependence on $a$ and smaller critical shear rates.

Direct observation of interlayer coherent acoustic phonon dynamics in bilayer and few-layer PtSe2

This work reports the real-time observation of the interlayer lattice vibrations in bilayer and few-layer PtSe2 by means of the coherent phonon method. The layer-breathing mode and standing wave mode of the interlayer vibrations are found to coexist in such a kind of group-10 transition metal dichalcogenides (TMDCs). The interlayer breathing force constant standing for perpendicular coupling (per effective atom) is derived as 7.5 N/m, 2.5 times larger than that of graphene. The interlayer shearing force constant is comparable to the interlayer breathing force constant, which indicates that PtSe2 has nearly isotropic interlayer coupling. The low-frequency Raman spectroscopy elucidates the polarization behavior of the layer-breathing mode that is assigned to have A1g symmetry. The standing wave mode shows redshift with the increasing number of layers, which successfully determines the out-of-plane sound velocity of PtSe2 experimentally. Our results manifest that the coherent phonon method is a good tool to uncover the interlayer lattice vibrations, beyond the conventional Raman spectroscopy limit. The strong interlayer interaction in group-10 TMDCs reveals their promising potential in high-frequency (∼terahertz) micro-mechanical resonators.

Dynamic Response and Vibration Isolation Analysis of Very Large Floating Building under Wave Action

Taking the buildings above the very large floating structures as research object, the finite element software ANSYS/AQWA was used to carry out hydrodynamic analysis of the single module very large floating structure, and the motion response parameters were obtained. A common multi-layer steel frame structure model and a multi-layer steel frame structure model with three-dimensional vibration isolation bearings were established by using SAP2000, and dynamic time history analysis was carried out for these two steel frame building models. Studies have shown that the motion response of the very large floating structures under the action of waves can not be ignored for the upper building. After the vibration isolation bearing is added to the floating buildings, the natural vibration period of the upper steel frame structure is significantly extended, the inter-layer shear force is slightly reduced, and the inter-layer shear force, interlayer displacement and floor acceleration are increased. Compared with the installation of vibration isolation bearings for land buildings, the vibration isolation of offshore floating buildings is not effective.

Moiré-pattern fluctuations and electron-phason coupling in twisted bilayer graphene

In twisted bilayer graphene, long-wavelength lattice fluctuations on the scale of the moir\'e period are dominated by phason modes, i.e., acoustic branches of the incommensurate lattice resulting from coherent superpositions of optical phonons. In the limit of small twist angles, these modes describe the sliding motion of stacking domain walls separating regions of partial commensuration. The resulting soliton network is a soft elastic manifold, whose reduced rigidity arises from the competition between intralayer (elastic) and interlayer (adhesion) forces governing lattice relaxation. Shear deformations of the beating pattern dominate the electron-phason coupling to the leading order in ${t}_{\ensuremath{\perp}}/t$, the ratio between interlayer and intralayer hopping parameters. This coupling lifts the layer degeneracy of the Dirac cones at the corners of the moir\'e Brillouin zone, which could explain the observed fourfold (instead of eightfold) Landau level degeneracy. Electron-phason scattering gives rise to a linear-in-temperature contribution to the resistivity that increases with decreasing twist angle due to the reduction of the stiffness of the soliton network. This contribution alone, however, seems to be insufficient to explain the huge enhancement of the resistivity of the normal state close to the magic angle.

Efficient thermal conductivity modulation by manipulating interlayer interactions: A comparative study of bilayer graphene and graphite

The application of graphene in high-performance thermal management has received a lot of attention in recent years, which still needs further exploration and development. Here, based on first-principles calculations, the thermal transport is found to be efficiently modulated by enhancing interlayer interactions in bilayer graphene (BLG), showing a different trend compared to graphite. The results of our work suggest that, by enhancing the interlayer force, the “in-plane” anharmonic phonon transport of BLG while the “out-of-plane” harmonic phonon transport of graphite can be effectively tuned. By manipulating interlayer interactions, a controllable and directed parameter (6% out-of-plane compressing deformation of BLG can achieve more than 25% decrement of in-plane thermal conductivity; 10% out-of-plane compressing deformation of graphite can increase out-of-plane thermal conductivity by more than 5 times) for tuning the thermal conductivity can be achieved. The difference in the effect of the interlayer force on thermal conductivity for low-dimensional and bulk materials emphasizes the significance of the anharmonic phonon transport properties of low-dimensional materials with interlayer interaction and thereby provides an important insight for promoting the future application of bilayer graphene and graphite.

Nonlinear vibrations of single- and double-walled carbon nanotubes resting on two-parameter foundation in a magneto-thermal environment

The excellent mechanical, electrical, structural and thermal properties coupled with high strength to weight ratio of carbon nanotubes have tremendously expanded their applications in various industrial, engineering, physical and natural sciences processes. In this work, nonlocal elasticity theory is used to analyze nonlinear vibrations of single and double-walled carbon nanotubes resting on two-parameter foundation in a thermal and magnetic environment. With the aid of Galerkin decomposition method, the systems of nonlinear partial differential equations are transformed into systems of nonlinear ordinary differential equations which are solved using homotopy perturbation method. The developed analytical solutions are used to investigate the influences of elastic foundations, magnetic field, temperature rise, interlayer forces, small scale parameter and boundary conditions on the frequency ratio. From the results, it is observed that the frequency ratio for all boundary conditions decreases as the number of walls increases from single to double. Also, it is established that the frequency ratio is highest for clamped–simple supported and lowest for clamped–clamped supported. Additionally, the results revealed that the frequency ratio decreases with increase in the value of spring constant (k1) temperature and magnetic field strength. This work will enhance the applications of carbon nanotubes in structural, electrical, mechanical and biological applications especially in a thermal and magnetic environment.

Control of coherence resonance by self-induced stochastic resonance in a multiplex neural network.

We consider a two-layer multiplex network of diffusively coupled FitzHugh-Nagumo (FHN) neurons in the excitable regime. We show that the phenomenon of coherence resonance (CR) in one layer can not only be controlled by the network topology, the intra- and interlayer time-delayed couplings, but also by another phenomenon, namely, self-induced stochastic resonance (SISR) in the other layer. Numerical computations show that when the layers are isolated, each of these noise-induced phenomena is weakened (strengthened) by a sparser (denser) ring network topology, stronger (weaker) intralayer coupling forces, and longer (shorter) intralayer time delays. However, CR shows a much higher sensitivity than SISR to changes in these control parameters. It is also shown, in contrast to SISR in a single isolated FHN neuron, that the maximum noise amplitude at which SISR occurs in the network of coupled FHN neurons is controllable, especially in the regime of strong coupling forces and long time delays. In order to use SISR in the first layer of the multiplex network to control CR in the second layer, we first choose the control parameters of the second layer in isolation such that in one case CR is poor and in another case, nonexistent. It is then shown that a pronounced SISR can not only significantly improve a poor CR, but can also induce a pronounced CR, which was nonexistent in the isolated second layer. In contrast to strong intralayer coupling forces, strong interlayer coupling forces are found to enhance CR, while long interlayer time delays, just as long intralayer time delays, deteriorate CR. Most importantly, we find that in a strong interlayer coupling regime, SISR in the first layer performs better than CR in enhancing CR in the second layer. But in a weak interlayer coupling regime, CR in the first layer performs better than SISR in enhancing CR in the second layer. Our results could find novel applications in noisy neural network dynamics and engineering.

Electronic and Optical Properties of Two-Dimensional Tellurene: From First-Principles Calculations.

Tellurene is a new-emerging two-dimensional anisotropic semiconductor, with fascinating electric and optical properties that differ dramatically from the bulk counterpart. In this work, the layer dependent electronic and optical properties of few-layer Tellurene has been calculated with the density functional theory (DFT). It shows that the band gap of the Tellurene changes from direct to indirect when layer number changes from monolayer (1 L) to few-layers (2 L–6 L) due to structural reconstruction. Tellurene also has an energy gap that can be tuned from 1.0 eV (1 L) to 0.3 eV (6 L). Furthermore, due to the interplay of spin–orbit coupling (SOC) and disappearance of inversion symmetry in odd-numbered layer structures resulting in the anisotropic SOC splitting, the decrease of the band gap with an increasing layer number is not monotonic but rather shows an odd-even quantum confinement effect. The optical results in Tellurene are layer dependent and different in E ⊥ C and E || C directions. The correlations between the structure, the electronic and optical properties of the Tellurene have been identified. Despite the weak nature of interlayer forces in their structure, their electronic and optical properties are highly dependent on the number of layers and highly anisotropic. These results are essential in the realization of its full potential and recommended for experimental exploration.

Interlayer Attraction Force in Concentric Carbon Nanotubes

The interlayer attraction force between concentric carbon nanotubes (CNTs) plays an important role in CNT-based nanodevices. However, the precise measurement of the interlayer attraction force remains to date a challenge. Although theoretical investigations have identified the dependence of the interlayer attraction force on the tube radius, no explicit relation for such dependence has been established so far. Here, based on an analytical model, we find that the interlayer attraction force between two telescoping concentric CNTs is proportional to the mean (but not the inner nor the outer) radius of the contacting two tubes and consequently propose an explicit expression that relates the interlayer attraction force with the mean radius as well as the interlayer spacing. We also implement the effect of temperature in the present expression based on the linear dependence of the attraction force on temperature. The present expression can be compared with the existing theoretical and experimental results, offering an efficient way to evaluate the interlayer attraction force in the nanodevices composed of concentric CNTs.

Ultrasound-Assisted Alkaline Solution Reflux for As-Exfoliated MoS2 Nanosheets.

A facile approach was developed to produce MoS2 nanosheets by ultrasound-assisted reflux exfoliation, which was highly efficient for large-scale production and sustainable for environment. The interlayer force of bulk MoS2 was first exhausted in employing LiOH/NaOH solution by reflux and thereafter quickly exfoliated by ultrasound. The lateral size of the as-prepared MoS2 nanosheets with about 2–9 layers became smaller. Definitely, the average friction coefficient and wear scar diameter of 0.08 wt % MoS2-based oil decreased by about 21.87 and 38.09% relative to the base oil, which displayed better antifriction and antiwear performances.

Substrates and interlayer coupling effects on Mo1−xWxSe2 alloys

Two-dimensional (2D) transition metal dichalcogenides alloys are potential materials in the application of photodetectors over a wide spectral range due to their composition-dependent bandgaps. The study of bandgap engineering is important for the application of 2D materials in devices. Here, we grow the Mo1−xWxSe2 alloys on mica, sapphire and SiO2/Si substrates by chemical vapor deposition (CVD) method. Mo1−xWxSe2 alloys are grown on the mica substrates by CVD method for the first time. Photoluminescence (PL) spectroscopy is used to investigate the effects of substrates and interlayer coupling force on the optical bandgaps of as-grown Mo1−xWxSe2 alloys. We find that the substrates used in this work have an ignorable effect on the optical bandgaps of as-grown Mo1−xWxSe2. The interlayer coupling effect on the optical bandgaps of as-grown Mo1−xWxSe2 is larger than the substrates effect. These findings provide a new way for the future study of the growth and physical properties of 2D alloy materials.

Half-unit-cell ZnIn2S4 monolayer with sulfur vacancies for photocatalytic hydrogen evolution

Two-dimensional (2D) photocatalytic materials have attracted extensive attention due to the unique properties different from those of their bulk. 2D ZnIn2S4 nanosheets with the intrinsic bilayer in one-unit-cell with interlayer force generally perform better than that of the bulk in photocatalytic hydrogen evolution. Here, we for the first time demonstrate that the half-unit-cell ZnIn2S4 monolayer possesses an excellent photocatalytic performance compared with the one-unit-cell bilayer owing to its increased carrier lifetime. Meanwhile, sulfur vacancies are introduced in the half-unit-cell ZnIn2S4 monolayer to trap the photo-generated electrons and further prolong the carrier lifetime. First-principle calculations reveal that sulfur vacancies in the ZnIn2S4 monolayer induce more charge carriers at the valence band maximum to participate in the photocatalytic activity. As expected, the photocatalytic hydrogen production rate of the monolayer ZnIn2S4 with sulfur vacancies is up to 13.478 mmol/g/h under the visible light irradiation, which is much higher than the available values reported of ZnIn2S4 so far. These findings provide a new strategy for optimization of 2D photocatalysts to enhance photocatalytic hydrogen evolution.

Interlayer interaction on twisted interface in incommensurate stacking MoS2: A Raman spectroscopy study

In the present work, properties of the interlayer breathing modes in twisted MoS2 samples with different structures are carefully examined. The distribution of peak position of the breathing modes is mainly dependent on overall layer numbers, and is only slightly affected by specific structure of the sample. Linear chain model calculation shows quantitatively a markedly decrease in interlayer force on the twisted interface, and slight difference in Raman frequency may mean considerable difference in interlayer force. When one or both of the component layers get too thick, no new breathing modes can be found, indicating that rigidity of the component may affect the coupling efficiency. Our work demonstrates that low-frequency Raman spectroscopy can act as an effective indirect strategy for the detection of interlayer interaction, which is a good complement to existing methods such as AFM technologies.