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The study of Frequency Selective Surface (FSS) by Direct ink writing (DIW) has attracted much attention due to the convenience and effectiveness of 3D printing technology. However, the limited printing precision of DIW has heavily restricted its applications as the electromagnetic performance is highly sensitive to it, especially the precision at the microscale. Herein, the ultra-high printing precision of FSS was achieved through DIW by the uniformly dispersed graphene sheets to deeply modify the rheological behavior and the steric hindrance effect. Thus, the highly precision of the printed filament width as thin as 67 μm with a space of only 42 μm were achieved, which is difficult for conventional DIW, and no structural distortion is found after 3D printing, no matter it was 2D printed on a flat surface or the sharply skewed hook face, or even 3D printed to architectural structures. According to the highly improved precision, the electromagnetic performance matching between the designed model and the printed physical FSS device was perfectly achieved, reducing the center frequency error less than 0.3 GHz, and the transmission coefficient error less than 0.046. Our work promises an effective and easy preparation of high-quality FSS from the aid of graphene.

The commercialized binder carboxymethyl cellulose sodium (CMC-Na) is considered unsuitable for micro-sized SiOx anode as it cannot endure the large volume change to retain the conductive network during repeated charge/discharge cycles. Herein, a small amount of silicon nano particles (SiNPs) is added during slurry preparation process as “nano-combs” to unfold the convoluted CMC-Na polymer chains so that they undergo a coil-to-stretch transition by interaction between polar groups (e.g -OH, -COONa) of polymer and SiNPs’ large surface. Through maximizing the utilization of binders, a uniform conductive network is constructed with increased interfacial contact with micro-sized SiOx. As a result, the SiOx electrode with optimized (10 wt%) SiNPs addition shows significantly improved initial capacity as well as cycling performance. Through revisiting CMC-Na, a currently deemed unqualified binder in SiOx anode, this work gives a brand-new perspective on the failing mechanism of Si-based anode materials as well as an improving strategy for electrode preparation.

Developing new electrode materials is one of the keys to improving the energy density of supercapacitors. In this article, a novel cobalt polysulfide/carbon nanofibers (C,N-CoxSy/CNF) film derived from zeolitic imidazolate framework is first prepared by a facile strategy. The composite material with two-dimensional leaf-shaped nanoarray neatly grown on the surface of carbon nanofibers is composed of CoS, CoS2, Co9S8, N-doped carbon nanosheets, and carbon nanofibers. It is found that the composite can not only increase the contact area with the electrolyte but also provide abundant redox-active sites and a Faraday capacitance for the entire electrode. The C,N-CoxSy/CNF composite exhibits excellent electrochemical properties, including a high capacity of up to 1080F g -1 at 1 A g -1 and a good rate capability (80.4 % from 1 A g -1 to 10 A g -1). A C,N-CoxSy/CNF//AC asymmetric supercapacitor device is assembled using C,N-CoxSy/CNF as the positive electrode and activated carbon as the negative electrode, showing high energy density (37.29 Wh kg -1@813.6 W kg -1) and good cycle stability (90.5% of initial specific capacitance at 10 g−1 after 5000 cycles). This C,N-CoxSy/CNF composite material may also be used as a potential electrode for future lithium-ion batteries, zinc-ion batteries, lithium-sulfur batteries, etc.

The design of efficient, stable, and economical electrocatalysts for oxygen and hydrogen evolution reaction (OER and HER) is a major challenge for overall water splitting. Herein, a hierarchical structured CoP/carbon nanofibers (CNFs) composite was successfully synthesized and its potential application as a high-efficiency bifunctional electrocatalyst for overall splitting water was evaluated. The synergetic effect of two-dimensional (2D) CoP nanosheets and one-dimensional (1D) CNFs endowed the CoP/CNFs composites with abundant active sites and rapid electron and mass transport pathways, and thereby significantly improved the electrocatalytic performances. The optimized CoP/CNFs delivered a current density of 10 mA cm−2 at low overpotential of 325 mV for OER and 225 mV for HER. In the overall water splitting, CoP/CNFs achieved a low potential of 1.65 V at 10 mA cm−2. The facile strategy provided in the present work can facilitate the design and development of multifunctional non-noble metal catalysts for energy applications.

As a typical transition metal oxide anode material, ZnMoO4 can deliver a higher theoretical capacity of 951.6 mAh g−1 due to its variable oxidation state and alloying reaction. However, lower conductivity and huge volumetric expansion restrict its further development. Herein, the modified sol–gel method is applied to synthesize a series of (1-x)ZnMoO4-xZnFe2O4 (x = 0.1, 0.2, 0.3, 0.4, and 0.5) composites. The effects of compound proportion of ZnFe2O4 on the crystal phase structure and morphology for ZnMoO4 have been investigated in detail. All the composites have been conducted on electrochemical measurements, and the results illustrate that the composites display better electrochemical performance than that of ZnMoO4. Especially for 0.6ZnMoO4-0.4ZnFe2O4, it can deliver a capacity of 550.7 mAh g−1 after 500 cycles at a current density of 200 mA g−1. Moreover, it also presents the higher capacity at higher current density. The improvement of electrochemical performance should be attributed to the synergistic effect of ZnFe2O4 and ZnMoO4.

Currently, advancements in separator technology for lithium-ion batteries (LIBs) have been developed due to their widespread use and key role in ion transportation. Nevertheless, there is still a need for ensuring the operation safety, service life, and user's experience of the batteries. In order to avoid the safety issues caused by the elevating temperature during working process, it is essential to endow separators with thermal shutdown function, which can timely cut off the current and prevent the electrodes from contacting. At the same time, the demand for recycling and sustainability of separators are also growing. Therefore, functional separators with irreversible or reversible thermal shutdown ability came out for future utility and manufacture. In this review, we aim to provide a comprehensive analysis of the technologies employed to enhance the safety of LIBs via highlighting the recent achievements in separators with irreversible thermal protection fabricated by different methods and mechanisms. Moreover, we summarize the intelligent materials that are able to take actions and self-adapt in reversibly thermal protection separators. Current research directions and challenges associated with the use of these LIBs separators and future perspectives in battery thermal protection are also provided. We hope such a review could provide inspiration for the separator researches dedicated on the cyclic utilization, high safety and high performance for future battery developments.

Aggregation-induced emission enhancement (AIEE) is a process recently exploited in solid-state materials and organic luminophores, and it is explained by tight-molecular packaging. However, solution-phase AIEE and its formation mechanism have not been widely explored. This work investigated AIEE phenomena in two donor-acceptor-donor-type benzodiazole-based molecules (the organic building block in metal-organic frameworks) with an acetylene and phenyl π-conjugated backbone tapered with a carboxylic acid group at either end. This was done using time-resolved electronic and vibrational spectroscopy in conjunction with time-dependent density functional theory (TD-DFT) calculations. Fluorescence up-conversion spectroscopy and time-correlated single-photon counting conclusively showed an intramolecular charge transfer-driven aggregate emission enhancement. This is shown by a red spectral shift of the emission spectra as well as an increase in the fluorescence lifetime from 746 ps at 1.0 × 10-11 to 2.48 ns at 2.0 × 10-3 M. The TD-DFT calculations showed that a restricted intramolecular rotation mechanism is responsible for the enhanced emission. The femtosecond infrared (IR) transient absorption results directly revealed the structural dynamics of aggregate formation, as evident from the evolution of the C≡C vibrational marker mode of the acetylene unit upon photoexcitation. Moreover, the IR data clearly indicated that the aggregation process occurred over a time scale of 10 ps, which is consistent with the fluorescence up-conversion results. Interestingly, time-resolved results and DFT calculations clearly demonstrated that both acetylene bonds and the sulfur atom are the key requirements to achieve such a controllable aggregation-induced fluorescence enhancement. The finding of the work not only shows how slight changes in the chemical structure of fluorescent chromophores could make a tremendous change in their optical behavior but also prompts a surge of research into a profound understanding of the mechanistic origins of this phenomenon. This may lead to the discovery of new chemical strategies that aim to synthesize novel chromophores with excellent optical properties for light-harvesting applications.

The modulation of exciton-phonon coupling by strain greatly affects the optical and optoelectronic properties of two-dimensional (2D) materials. Although photoluminescence and optical absorption spectra have been used to characterize the overall change of exciton-phonon coupling under strain, there has been no effective method to distinguish the evolution of the major contributions of exciton-phonon coupling, that is, deformation potential (DP) and Frohlich interaction (FI). Here we report the direct monitoring of the evolution of DP and FI under strain in layered MoS2 using circularly polarized Raman spectroscopy. We found that the relative proportions of DP and FI can be well evaluated by the circular polarization ratio of the E2g1 mode for strained MoS2. Further, we demonstrated that the strain control of DP and FI in MoS2 is dominated by the excitonic effect. Our method can be extended to other 2D semiconductors and would be helpful for manipulating exciton-phonon couplings by strain.

The bandgap characteristics of periodic structures show a great application prospect in seismic isolation and vibration mitigation. A T-shaped partially embedded periodic pile barrier is designed and studied based on the Bloch’s theorem. The proposed structure is fabricated and tested in field experiment to validate the simulation and the isolation performance. Good agreements are observed between the measured and the corresponding simulated results which present effective isolation for surface waves. The influences of the embedded length in the soil and the arrangement of the pile are investigated. The results show that the embedded length is the key parameter affecting the vibration attenuation. The smaller the embedded length, the lower the frequency of attenuation zone, and thanks to the embedded length; the proposed barrier exhibits better performances than the fully embedded and non-embedded barriers in maximum bandgap width, tunability, and feasibility in engineering. Gradient distribution of the embedded length leads to a wider frequency range of attenuation.

The twisted structure of strand is ignored and the resistance of all parallel copper strands is assumed to be at the same temperature in existing temperature estimation method of water cooling stator windings. However, the twisted structure leads to the changing of thermal source and cooling structure, the uneven thermal distribution of parallel copper strands leads to uneven resistance distribution, both of which will influence thermal distribution of stator windings and should be considered in the temperature estimation method. In this study, the temperature estimation method considering twisted structure and uneven resistance distribution is first proposed, called three‐dimensional (3‐D) network method, in which the nodes of circuit network and thermal network are completely consistent. Then, the water cooling stator winding of a 1240‐MW turbo generator is taken as an example, the thermal distribution of which are calculated by the proposed method and validated by both short‐circuit type test data and 3‐D finite element method (FEM). Finally, the influence of twisted structure and resistance distribution on the thermal distribution is analysed in detail. The results show that the twisted structure has a great effect on thermal distribution, which cannot be ignored, while the resistance distribution has little effect on thermal distribution.

The demand for sustainable energy sources urges the development of efficient and earth-abundant electrocatalysts. Herein, chlorine assisted ion-exchange and in-situ sulfurization processes were combined to construct CuCo2S4@(Cu,Co)2Cl(OH)3 heterostructures from Cu(OH)2 nanoarrays. Chlorine element in the cobalt source stimulated the formation of (Cu,Co)2Cl(OH)3 precursor, and further facilitated partial transformation of the precursor to CuCo2S4 on the surface to achieve composite structure. The mixed valences of Co element (Co3+ in CuCo2S4 and Co2+ in (Cu,Co)2Cl(OH)3) and O S interpenetrated nanointerface in the composite catalysts provided low electron transfer resistance for good alkaline oxygen evolution reaction (OER) activities. In 1 mol L−1 KOH electrolyte, the overpotentials of the optimal composite catalyst reached 253 and 290 mV respectively at the current density of 20 and 50 mA cm−2, which is comparable to the activity of commercial Ir/C (281 mV@20 mA cm−2). These findings could provide opportunities for designing effective and inexpensive composite electrocatalysts through nanointerface engineering strategy.

As phase change materials (PCMs), Sb–Te based alloys have received a lot of attention in recent years. However, the mechanism for the formation of the alloy and its application as PCMs is not fully understood. The high-throughput First-principles calculations and melt-quench ab initio molecular dynamics simulations were adopted to explore the microstructure and properties of Sb–Te alloys in this work. The hetero-atomic interaction and disordered distribution make Sb–Te alloy with layered microstructure more stable. Although Sb1−xTex solid solution is the metastable phase, it is still stable for PCMs in the certain ranges of solid solubility (0.4

Hydrostatic thrust bearings have been applied in high speed and heavy load machine tools because they provide superior characteristics such as higher positional accuracy, greater stability, and lower friction. The energy consumption of the fluid system exceeds 40% of the total energy consumption of the machine tools To reduce the energy consumption, it is usually necessary to optimize comprehensive tribological properties of multi-pad hydrostatic thrust bearing in CNC vertical processing equipment from the perspective of the oil recess structure. Effects of oil recess structural parameters on comprehensive tribological properties in multi-pad hydrostatic thrust bearing are investigated using CFD (Computational Fluid Dynamics) and lubrication theory. Focusing on this problem, this study comprehensively investigates the effects of oil recess shape, oil recess depth, land width on the tribological properties of hydrostatic thrust bearing using numerical simulation method. The relationships between the optimal comprehensive tribological properties and structural parameters are determined. An experimental rig is set up to verify the correctness of the numerical simulation method. The results indicate that to get an optimal comprehensive performance from hydrostatic bearing based on low power consumption, it is necessary to choose a proper of oil recess structural parameters.

Transition metal oxides (TMOs) based compounds are recognized as high-energy anodes in next-generation lithium-ion batteries (LIBs) due to their extremely high theoretical capacity. However, the lower intrinsic conductivity, fast fading cyclic stability and dramatic volume expansion during discharge/charge processes greatly hinder the practical application of TMOs as anodes in LIBs. In this study, we have designed and constructed MoO3/ZnCo2O4 QDs@C@rGO/MoO3 (denoted as GMZCO) sandwich-structured hybrid nanocomposites via an effective route, and have proposed the formation mechanism of this unique nanostructured composite on the basis of the systematic results of the microstructures. Due to the unique sandwich structure and the synergistic enhancement effect of the ZnCo2O4 QDs, α-MoO3 and rGO, the as-constructed GMZCO exhibits the superior electrochemical performances when used as anode for LIBs. The obtained GMZCO can maintain high capacity of 1281 mAh g−1 at 0.2 A g−1 after 300 cycles, and can deliver as high as specific capacity of 913 mAh g−1 at 1 A g−1 after 500 cycles, revealing the higher capacity and excellent cyclic stability. What deserves to be mentioned most is that GMZCO can keep a capacity of 541 mAh g−1 after 1400 cycles even at higher current density of 3 A g−1, having outstanding rate capability. This work paves a novel approach for design TMOs with unique microstructures as a promising anode for the high-performances LIBs.

Inclusions can lead to various defects in the final steel products, and RH vacuum refining is an effective and vital technology to remove inclusions from molten steel. By the computational fluid dynamics (CFD) method, the inclusion mass/population conservation model is developed to have a deep insight into the inclusion transfer behavior in the argon molten steel flow of RH. Particularly, the argon slip velocity is introduced into the inclusion convection velocity in the mathematical model, and the inclusions attached by argon bubbles can return to the molten steel when bubbles escape from the free surface of the vacuum chamber. The numerical results of the fluid flow and the inclusion transfer behavior are validated by the measured data in the actual experiment. The argon bubbles significantly enhance the inclusion transport and collision-coalescence process. Besides, the variations of the inclusion volume concentration and the inclusion number density in the up snorkel are about 2 times those in the down snorkel. The number of inclusions with diameters less than 10 μm decreases with the vacuum treatment time, while the number of inclusions with diameters greater than 10 μm increases first and then decreases gradually. Near the free surface of the ladle, there are the greatest inclusion volume concentration, the greatest inclusion number density and the lowest inclusion characteristic radius.

The N-bearing 19Cr-LDSS (Lean Duplex Stainless Steel, LDSS) with heterostructure consisting of coarse-grained ferrite and ultrafine-grained austenite was prepared by combining severe plastic deformation with High Temperature-Short Time (HTST) heat treatment. The microstructural observations and measurements were performed on deformed and annealed samples to correlate the excellent strength-plasticity matching to the grain refining and transformation-induced plasticity (TRIP) effect. The heterogeneous structure revealed a remarkable improvement of the strength compared to the counterparts processed by the conventional solution treatment. A yield strength (YS) of 800 MPa, ultimate tensile strength (UTS) of 1100 MPa and total elongation (TE) of 45% were achieved by the HTST treatment. Therefore, the higher YS and UTS of 19Cr-LDSS under HTST treatment were obtained on the premise of ensuring the excellent strength-plasticity matching. The high strength was provided by the grain refinement, and the high uniform elongation was attributed to the persistent high strain hardening rate due to the hetero-deformation-induced stress associated with the activation of TRIP effect. Meanwhile, the strain accommodation of coarse-grained ferrite phase also contributed to the improvement of plasticity for the experimental steel.

ConspectusPolymer-based organic field-effect transistors (OFETs) have attracted great attention owing to their significantly improved performance and the recently emerged prospects for broad applic...

Lithium-sulfur (Li-S) batteries are regarded as a promising next-generation system for advanced energy storage owing to a high theoretical energy density of 2600 Wh kg-1 . However, the practical implementation of Li-S batteries has been thwarted by the detrimental shuttling behavior of polysulfides, and the sluggish kinetics in electrochemical processes. Herein, a novel single atom (SA) catalyst with oversaturated Fe-N5 coordination structure (Fe-N5 -C) is precisely synthesized by an absorption-pyrolysis strategy and introduced as an effective sulfur host material. The experimental characterizations and theoretical calculations reveal synergism between atomically dispersed Fe-N5 active sites and the unique carbon support. The results exhibit that the sulfur composite cathode built on the Fe-N5 -C can not only adsorb polysulfides via chemical interaction, but also boost the redox reaction kinetics, thus mitigating the shuttle effect. Meanwhile, the robust three-dimensional nitrogen doped carbon nanofiber with large surface area, and high porosity enables strong physical confinement and fast electron/ion transfer process. Attributed to such unique features, Li-S batteries with S/Fe-N5 -C composite cathode realize outstanding cyclability and rate capability, as well as high areal capacities under raised sulfur loading, which demonstrates great potential in developing advanced Li-S batteries.

Rational design of electrode with hierarchical charge-transfer structure and good electronic conductivity is important to achieve high specific capacitance and energy density for supercapacitor, but it still remains a challenge. Herein, a nitrogen, sulfur co-doped pollen-derived carbon/graphene (PCG) composite with interconnected “sphere-in-layer” structure was fabricated, in which hierarchically pollen-derived carbon microspheres can serve as “porous spacers” to prevent the agglomeration of graphene nanosheets. The optimized PCG composite prepared with 0.5 wt% of graphene oxide (PCG-0.5) exhibited high specific capacitance (420 F g−1 at 1 A g−1), rate performance (280 F g−1 at 20 A g−1), and excellent cycling stability with 94% of capacitance retention after 10,000 cycles. The symmetrical device delivered a remarkable energy density of 31.3 Wh kg−1 in neutral medium. Moreover, density functional theory calculation revealed that PCG electrode possessed the accelerated charge transfer and enhanced electronic conductivity, thus ensuring a remarkable electrochemical performance. This work may afford an effective strategy for the development of biomass-derived carbon electrodes with novel charge-transfer structure toward supercapacitor applications.

Developing low-cost and high-efficiency bifunctional electrocatalysts for both oxygen evolution and reduction reactions is urgent to fulfill the practical application of rechargeable Zn-air batteries (ZABs). However, to explore the high catalytic performance of air electrocatalysts still remains a challenge. In response, a three-dimensionally ordered macroporous (3DOM) Co3O4 electrocatalyst is designed and synthesized through a nanocasting strategy. A well-controlled phosphorization treatment is further conducted to induce defect engineering on the resulting P-doped Co3O4–δ (3DOM P-Co3O4–δ). With the oxygen vacancy (Vo) tailoring, partial reduction from Co3+ to Co2+ is verified as the key to improving the intrinsic electrocatalytic bifunctionality. By incorporating the geometric and electronic merits, 3DOM P-Co3O4–δ possesses an ORR half-wave potential of 0.82 V and an OER overpotential of 366 mV to achieve 10 mA cm–2, which is comparable to noble-metal benchmarks. Particularly, under galvanostatic cycling measurements, ZABs using 3DOM P-Co3O4–δ containing air cathode showcase a potential gap of 0.84 V with negligible voltage fading over 250 h at 10 mA cm–2.

Herein, a series of alpha-Co(OH)2/reduced graphene oxide (rGO) microfilms and film-based nanodevices were developed via a new scalable technique. Due to the unique hexagonal nanoplates of ultrathin alpha-Co(OH)2 and the intrinsically conductive nature of rGO sheets, such thin films not only can improve the conductivity of alpha-Co(OH)2 and prevent the re-stacking of alpha-Co(OH)2 and rGO sheets but also short the transport routes of electrons and ions between the electrode and the electrolyte. The optimized alpha-Co(OH)2/rGO flexible electrode presents high specific capacitance (273.86 mF/cm2 at 0.1 mA/cm2), advanced rate capability, and excellent coulombic efficiency. Simultaneously, in-sandwich symmetric and asymmetric supercapacitors assembled with polyvinyl alcohol-KOH gel as the solid-state electrolyte achieved high areal and volumetric specific capacitances. Furthermore, a self-assembled planar alpha-Co(OH)2/rGO micro-supercapacitor (MSC) delivers high specific area capacitance (130F/cm2 at 0.5 mA/cm2) and excellent energy density (20 mWh/cm3@56 mW/cm3), which are superior to most of the recently reported carbon-based and metal hydroxides/oxides/sulfides-based planar MSCs. Also, our planar MSC shows excellent cycling performance, good flexibility, and mechanical stability. This work promotes the syntheses of other two-dimensional metal hydroxides/rGO composite film for high-performance flexible micro-electronics.

Metallic lithium (Li) is regarded as the ideal anode material in lithium‐ion batteries due to its low electrochemical potential, highest theoretical energy density and low density. There are, however, still significant challenges to be addressed such as Li‐dendrite growth and low interfacial stability, which impede the practical application of Li metal anodes. In order to circumvent these shortcomings, herein, we present a gel polymer electrolyte containing imidazolium ionic liquid end groups with a perfluorinated alkyl chain (F‐IL) to achieve both high ionic conductivity and Li ion transference number by fundamentally altering the solubility of salt within the gel electrolyte through Lewis‐acidic segments in the polymer backbone. Moreover, the presence of F‐IL moieties decreased the binding affinity of Li cation towards the glycol chains, enabling a rapid transfer of Li cation within the gel network. These structural features enabled the immobilization of anions on the ionic liquid segments to alleviate the space‐charge effect while promoting stronger anion coordination and weaker cation coordination in the Lewis‐acidic polymers. Accordingly, we realized a high Li ion conductivity (9.16×10−3 S cm−1) and high Li ion transference number of 0.69 simultaneously, along with a good electrochemical stability up to 4.55 V, while effectively suppressing Li dendrite growth. Moreover, the gel polymer electrolyte exhibited stable cycling performance of the Li|Li symmetric cell of 9 mAh cm−2 for more than 1800 hours and retained 86.7 % of the original capacity after 250 cycles for lithium‐sulfur (Li‐S) full cell., A gel polymer electrolyte containing imidazolium ionic liquid end groups with a fluorinated alkyl chain (F‐IL) was developed to suppress Li dendrite growth by realizing both high ionic conductivity and Li ion transference number. Lewis‐acidic segments in the polymer backbone reduce the mobility of Li salt anion and decrease the binding affinity of Li cation towards the glycol chains.

Physicochemical, surface, and mechanical properties of three batches of T800 grade carbon fibers (CFs) treated with three kinds of sizing agents and Toray T800H CFs were characterized to study the effect of sizing agents on surface properties. Scanning electron microscopy for morphology, atomic force microscopy calculations, and results for the content of sizing agents showed that sizing agent B improved the surface roughness and CFs with high content of sizing agent always presented small surface roughness in a certain content range 1.2–1.6%. Surface energy of CFs was calculated by Young’s contact angle using the test results with water and glycol, and contact angles with LY-1 and modified-AC531 were also acquired. The results proved that CFs of sizing agent group B had the highest average surface energy and the lowest average contact angles with both LY-1 and modified-AC531. From both single-filament and tensile strength test results, the average strength of CFs of sizing agent group B was found to be the lowest, which indicated that sizing agent B had an influence on tensile strength decrease of T800 grade CFs. Comparing the results of interfacial shear strength both in a natural dry state and after hygrothermal treatment, high surface energy was found to be the key element to obtain high interfacial adhesion between T800 grade CFs and bismaleimide, and high surface roughness and low contact angle also played important roles. Among sizing agents A, B, and C, A had an effect on the interfacial shear strength decrease of CFs in the natural dry state, while C had that after hygrothermal treatment.

In this work, we report a facile dealloying strategy to tailor the surface state of nanoporous TiO2 towards high-efficiency sulfur host material for lithium-sulfur (Li-S) batteries. When used as a sulfur cathode material, the oxygen-deficient TiO2-x exhibits enhanced lithium polysulfides (LiPS) adsorption and conversion kinetics that effectively tackle the shuttle effect in lithium-sulfur batteries. The excellent ability of the oxygen vacancy sites on TiO2-x surface to trap LiPS is proved by experimental observations and density functional theory (DFT) calculations. Meanwhile, it also promotes conversion kinetics of lithium polysulfides, as verified by the asymmetric cell experiment. Accordingly, compared with the S/TiO2 cathode, the oxygen-deficient S/TiO2-x electrode exhibits preeminent rate and cycling performance in lithium-sulfur batteries: it delivers an ultra-low capacity decay of 0.039 % per cycle after 1000 cycles at 1 C. Tunning the surface state of metal oxides by dealloying method offers a new facile strategy to design efficient sulfur cathode materials for lithium-sulfur batteries.

A bilayer architecture was established to modify the negative temperature coefficient (NTC) properties of LaMnO3 thin films. By incorporating a Y2O3 interlayer, high electrical resistances and low material constants were achieved simultaneously. The proposed LaMnO3 and LaMnO3/Y2O3 bilayer thin films were fabricated on SiO2/Si(100) substrates using direct current (DC) magnetron sputtering, and the films were subjected to post-annealing at temperatures of 650, 700, 750, and 800 °C. The bilayer thin film had a linear temperature response to a wide temperature range (25–500 °C) compared to that of pristine LaMnO3 (25–90 °C). By optimizing the post-annealing temperature, a negligible resistance drift of 2.9% was obtained after aging the bilayer thin film at 300 °C for 150 h. Scanning electron microscopy, energy dispersive spectroscopy, and X-ray photoelectron spectroscopy were used to investigate the origin of the properties of the bilayer film. The results indicated that these features were caused by the decreased grain boundary area and the increased Mn4+/Mn3+ ratio with increasing annealing temperature. This work verified the usefulness of applying two thin film layers with differing electrical properties to adjust the overall electrical properties of NTC thermistors over a wide temperature range.

The hysteretic working capacity of reinforced masonry shear (RMS) walls has been estimated empirically and statistically referring to the structural ultimate state with considerable uncertainty. Th...

Raman spectroscopy is a fast and nondestructive characterization technique, which has been widely used for the characterization of the composition and structure information of various materials. The symmetry-dependent Raman tensor allows the detection of crystallographic orientation of materials by using polarization information. In this Perspective, we discuss polarized Raman spectroscopy as a powerful tool for determination of the crystallographic orientation of various materials. First, we introduce the basic principles of polarized Raman spectroscopy and the corresponding experimental setups; the determination of crystallographic orientation of two-dimensional (2D) materials with in-plane isotropy and in-plane anisotropy using linearly polarized Raman scattering are then discussed. Furthermore, we discuss that using circularly polarized Raman spectroscopy, the azimuthal angle of materials in three dimensions (3D) can be characterized. In the final section, we show that the orientation distribution of nanomaterial assemblies can be measured using polarized Raman spectroscopy by introducing the orientation distribution function.

Lithium-sulfur (Li-S) batteries have drawn a lot of attention owing to the high theoretical capacity of 1675 mAh g-1, environmental friendliness and relative abundance of sulfur. Nevertheless, the severe dissolution and migration of lithium polysulfides (LiPSs) and poor conductivity of sulfur greatly hinder the practical application of Li-S batteries. In this work, Fe-Ni-P@nitrogen-doped carbon (named as Fe-Ni-P@NC) derived from Fe-Ni Prussian blue analog (Fe-Ni PBA) was used as highly efficient sulfur host for Li-S batteries. The Fe-Ni-P particles not only enhance the adsorption of LiPSs but also effectively promote the conversion of LiPSs. In addition, the CN- of PBAs can readily generate nitrogen-doped carbon during pyrolysis, which can improve the conductivity of composites. Due to these advantages, Li-S batteries using S@Fe-Ni-P@NC composites cathodes exhibited good electrochemical performance with outstanding rate capability and stable cycling over 500 cycles with a lower capacity fading rate of 0.08% per cycle at 1 C.

In the work, a kind of composite material with excellent stab/puncture resistance was prepared by resin bonded Kevlar fabric. Water-borne epoxy resin (PAEK), polyacrylamide (APAM), fatty alcohol polyoxyethylene phosphate potassium salt (TFPK) are formulated to form a novel sizing agent that can be used for the sizing Kevlar fabrics. The effects of the sizing agent on the mechanical and stab/puncture resistance are examined. A field emission scanning electron microscopy (SEM), an ultra-depth of field 3d microscope, and a universal testing machine were used to observe and evaluate the morphology of sizing fabrics, the stab/puncture morphology, mechanical properties, and quasi-static stabbing properties, respectively. The test results show that the puncture resistance of the sizing Kevlar fabrics increases first and then decreases with the increase of sizing agent concentration. Compared with non-sizing fabrics, the Kevlar fabrics that are treated with a sizing agent at a concentration of 10 wt% have 524 % higher puncture resistance, 301 % higher stab resistance, and a 6.9-fold increase in the burst strength. Because the fiber bundles in the sizing fabrics are confined due to the resin saturation, the friction among fibers is enhanced and thus better resists an external force and contributes a greater resistance against sharp objects.

In this study, a series of butt welding tests with oscillating fiber laser beams were performed on zinc-coated thin sheets of 0.8 and 1.2 mm thicknesses. The optimized welding parameters were used to produce robust welds with no perforations or pores. The weld formation process, microstructure, and mechanical properties of welded joints with the butt surfaces processed via laser and shear cutting techniques were systematically investigated. Besides, the corrosion resistance of the laser oscillating welded joint was analyzed in detail. The welded joint with the butt surface processed by laser cutting shows less undercutting degree with a more favorable weld appearance. The two welded joints had similar microstructures containing different forms of ferrites. The heat-affected zone was almost identical to the base metal in microstructure but had larger grains. Widmanstatten ferrites’ content in the large-grained weld metal of welded joints with surface processed via laser cutting exceeded that of shear cutting-processed ones. The former had lower tensile strength than the latter, but their overall mechanical performance was better than base metal. After salt spray corrosion and electrochemical corrosion tests, the laser oscillating welded joint was only slightly corroded and exhibited no obvious deterioration in corrosion resistance.

We present a method for atomically precise nanocluster synthesis. As an illustration, we introduced the reducing-ligand induction combined method and synthesized a novel nanocluster, which was determined to be Au28 (SCH2 Ph-t Bu)22 with the same number of gold atoms as existing Au28 (SR)20 nanoclusters but different ligands (hetero-composition-homo-size). Compared with the latter, the former has distinct properties and structures. In particular, a novel kernel evolution pattern is reported, i.e., the quasi-linear growth of Au4 -tetrahedron by sharing one vertex and structural features, including a tritetrahedron kernel with two bridging thiolates and two Au6 (SCH2 Ph-t Bu)6 hexamer chair-like rings on the kernel surface were also first reported, which endow Au28 (SCH2 Ph-t Bu)22 with the best photoluminescence quantum yield among hydrophobic thiolated gold nanoclusters so far, probably due to the enhanced charge transfer from the bi-ring to the kernel via Au-Au bonds.

Fluorinated polyhedral oligomeric silsesquioxane (F-POSS) is one of the most popular candidates at present for superhydrophobic coating. Because of its ultralow surface energy, F-POSS has usually been dissolved with expensive fluoro-solvents, and the melting temperature of F-POSS is not high (122–140 °C), which will cause its loss during use. So trying to polymerize/crosslink F-POSS molecules and/or directly graft F-POSS to substrate is important. In this work, we report the SI-eATRP grafting of methacryl POSS (MA-POSS) on cotton and the subsequent amine catalyzed thiol-methacrylate Michael addition reaction of poly(MA-POSS) with 1H, 1H, 2H, 2H-perfluorododecyl-1-thiol (PFDT) for the fabrication of a durable poly(MA-POSS)-PFDT coating. The cotton fabric coated with poly(MA-POSS) was nearly superhydrophobic after 4 h of SI-eATRP process under potentiostatic condition of −0.40 V. Although the water contact angle (WCA) was ~148°, water droplets tended to adhere to the cotton fabric surface even when the fabric was turned upside down. After fluorination, WCA was increased to ~160°, and water drops could slide off when the fabric was slightly tilted. The sliding angle (SA) was ~10°. The as-prepared poly(MA-POSS)-PFDT coating was durable against repeated washing and physical abrasion. After 30 accelerated washing cycles (equals to 150 home laundering cycles), the coated fabric still showed superhydrophobicity. After 800 abrasion cycles over sandpaper, the WCA was still as high as 149°. In addition, the coated fabric had self-healing ability and could restore its superhydrophobicity after plasma etching through heat treatment. After 10 cycles of plasma etching and heat-induced healing process, the WCA of the coated fabric kept at ~154°. Such a durable superhydrophobic fabric coating may find applications in the development of functional clothing for a variety of purposes.

Stimuli-responsive surfaces with wettability change between superhydrophilic and superhydrophobic are susceptible to oil contamination which often ruins the surface. Herein, a coating with pH-switchable wettability transition between superamphiphobic and superhydrophilic-superoleophobic is achieved by rationally designing oleophobic/pH-responsive polymer heterogeneous chemistry. Fabrics modified with this coating show repellency to both water and oils, while upon exposure to acidic water (pH = 1) the fabrics change to be superhydrophilic-superoleophobic within a short response time of5 s. More importantly, the superamphiphobicity of the fabric can be restored under mild alkaline condition (pH = 10), and the transition is reversible for many cycles. The effective in situ or ex situ wettability change under acidic/alkaline water treatment makes the coated fabric capable of separating oil-water mixture or even some mixtures of immiscible organic solvents. In addition, the coated fabric is also demonstrated to be promising as a new class of functional fabrics that provide protection against water and many oils in one condition, and can change to be hygroscopic, anti-static, oil-repellent and anti-oil-fouling in the other condition for improved wear comfort and self-cleaning.

ZnCo2O4@Co9S8 nanostructures were grown on the surface of Ni foam by facile hydrothermal method and subsequent thermal treatment process, thus increasing the active site on the surface of the material. After vulcanization treatment, the performance of the composite material has been significantly improved the product has a higher specific capacitance of 1018.2 F g−1 at 4 A g−1. This work demonstrates that ZnCo2O4@Co9S8 nanostructures are highly desirable for application as advanced electrochemical electrode materials.

The selection of the most suitable crystal structure for ions storage and the investigation of the corresponding reaction mechanism is still an ongoing challenge for the development of Mg-based batteries. In this article, high flexible graphene network supporting different crystal structures of Nb2O5 (TT-Nb2O5@rGO and T-Nb2O5@rGO) are successfully synthesized by a spray-drying-assisted approach. The three-dimensional graphene framework provides high conductivity and avoids the aggregation of Nb2O5 nanoparticles. When employed as electrode materials for energy storage applications, TT-Nb2O5 delivers a higher discharge capacity of 129.5 mAh g−1, about twice that of T-Nb2O5 for Mg-storage, whereas, T-Nb2O5 delivers a much higher capacity (162 mAh g−1) compared with TT-Nb2O5 (129 mAh g−1) for Li-storage. Detailed investigations reveal the Mg intercalation mechanism and lower Mg2+ migration barriers, faster Mg2+ diffusion kinetics of TT-Nb2O5 as cathode material for Mg-storage, and the faster Li+ diffusion kinetics, shorter diffusion distance of T-Nb2O5 as cathode material for Li-storage. Our work demonstrates that exploring the proper crystal structure of Nb2O5 for different ions storage is necessary.

The preparation of superhydrophobic coating on the surface of aluminum alloy can effectively improve its performance in the harsh environment. In this work, a superhydrophobic coating with water contact angle (WCA) up to 157.5 ± 0.5° and sliding angle less than 3° is prepared on aluminum alloy 6061 substrate by simple and environment-friendly hydrothermal reaction and stearic acid modification. The in situ growth coating is composed of Zn-Al layered double hydroxide and the morphology of the coating was a micro–nano composite structure with micro-sheet and nano-needle. The stearic acid is combined with the coating by physical adsorption and chemical bonding. The superhydrophobic coating imparts the properties of low adhesion, self-cleaning, and anti-corrosion to the aluminum alloy substrate, and it also has good high-temperature stability, acid and alkali resistance, mechanical stability and time durableness. The superhydrophobic coating can spontaneously recover 7 times after damaged by oxygen plasma etching. The outstanding comprehensive performance of the coating makes it a promising application for protection of aluminum alloy.

Na 3 V 2 O 2 (PO 4 ) 2 F (NVOPF) as an attractive electrode material has received much attention based on the one-electron reaction of V 4+ /V 5+ . However, the electrochemical reactions involving lower vanadium valences were not investigated till now. Herein, we firstly synthesized a composite of graphene decorated nanosheet-assembled NVOPF microflowers (NVOPF/G) and conducted the multi-electron reaction of NVOPF/G by controlling the operation voltage windows. The reaction mechanism, structural changes and vanadium valences during the insertion/extraction of Li ions (from two to six) were elucidated clearly by in-situ X-ray diffraction and ex-situ X-ray photoelectron spectroscopy characterizations. Theoretical computations also reveal the Li ions locations in the structure of NaV 2 O 2 (PO 4 ) 2 F. Due to the additional redox couple of V 3+ /V 4+ , NVOPF/G displays a much higher initial capacity of 183.3 mAh g -1 in the wider voltage window of 1.0-4.8 V than that of 2.5-4.8 V (129.3 mAh g -1 ). Moreover, excellent Li-storage performance of NVOPF/G at a lower voltage (≤2.5 V) with the active reaction of V 2+ /V 3+ /V 4+ was obtained for the first time, demonstrating the high potential of NVOPF/G as an anode material for Li ion storage.