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Replacing micro-reinforcing fibers with carbon nanotubes (CNTs) is beneficial for improving the impact properties of ultra-high performance concrete (UHPC); however, the weak wettability and dispersibility of CNTs and the weakly bonded interface between CNTs and UHPC limit their effectiveness as composites. Therefore, this study aims to enhance the reinforcement effect of CNTs on the impact properties of UHPC via functionalization. Unlike ordinary CNTs, functionalized CNTs with carboxyl or hydroxyl groups can break the Si–O–Ca–O–Si coordination bond in the C–S–H gel and form a new network in the UHPC matrix, effectively inhibiting the dislocation slip inside UHPC matrix. Furthermore, functionalized CNTs, particularly carboxyl-functionalized CNTs, control the crystallization process and microscopic morphology of the hydration products, significantly decreasing and even eliminating the width of the aggregate–matrix interface transition zone of the UHPC. Moreover, the functionalized CNTs further decrease the attraction of the negatively charged silicate tetrahedron to Ca2+ in the C–S–H gel, while modifying the pore structure (particularly the nanoscale pore structure) of UHPC, leading to the expansion of the intermediate C–S–H layer. The changes in the microstructures of UHPC brought about by the functionalized CNTs significantly enhance its dynamic compressive strength, peak strain, impact toughness, and impact dissipation energy at strain rates of 200–800 s−1. Impact performance of UHPC containing a small amount of carboxyl-functionalized CNTs (especially the short ones) is generally better than that of UHPC containing hydroxyl-functionalized and ordinary CNTs; it is even superior to that of UHPC with a high steel fiber content.

To further explore the damage characteristics and impact response of the shaped charge to the solid rocket engine (SRE) in storage or transportation, protective armor was designed and the shelled charges model (SCM)/SRE with protective armor impacting by shaped charge tests were conducted. Air overpressures at 5 locations and axial acceleration caused by the explosion were measured, and the experimental results were compared with two air overpressure curves of propellant detonation obtained by related scholars. Afterwards, the finite element software AUTODYN was used to simulate the SCM impacted process and SRE detonation results. The penetration process and the formation cause of damage were analyzed. The detonation performance of TNT, reference propellant, and the propellant used in this experiment was compared. The axial acceleration caused by the explosion was also analyzed. By comprehensive comparison, the energy released by the detonation of this propellant is larger, and the HMX or Al particles contained in this propellant are more than the reference propellant, with a TNT equivalent of 1.168–1.196. Finally, advanced protection armor suggestions were proposed based on the theory of woven fabric rubber composite armor (WFRCA).

Metal–organic frameworks (MOFs) with high porosity and variable structure have attracted extensive attention in the field of electrochemistry, but their poor conductivity and stability have limited their development. Materials derived from MOFs can maintain the structural diversity and porosity characteristics of MOFs while improving their electrical conductivity and stability. Metal phosphides play an important role in electrochemistry because they possess rich active sites, unique physicochemical properties, and a porous structure. Published results show that MOF-derived metal-phosphides materials have great promise in the field of electrochemistry due to their controllable structure, high specific surface area, high stability and excellent electrical conductivity. MOF-derived metal-phosphides with significant electrochemical properties can be obtained by simply, economical and scalable synthetic methods. This work reviews the application of MOF-derived metal phosphides in electrochemistry. Specifically, the synthesis methodology and morphological characterization of MOFs derived metal-phosphides and their application in electrochemistry are described. Based on recent scientific advances, we discuss the challenges and opportunities for future research on MOF-derived metal-phosphides materials.

Three-dimensional (3D) printing, also known as additive manufacturing, has the advantages of low cost, easy structure operation, rapid prototyping, and easy customization. In the past few years, materials with different structures, compositions, and properties have been widely studied as prospects in the field of 3D printing. This paper reviews the synthesis methods and morphologies of one-, two- and three-dimensional micro/nano materials and their composites, as well as their applications in electrochemistry, such as supercapacitors, batteries, and electrocatalysis. The latest progress and breakthroughs in the synthesis and application of different structural materials in 3D-printing materials, as well as the challenges and prospects of electrochemical applications, are discussed.

A series of novel red-emitting BaLiZn3(BO3)3:Eu3+ phosphors was synthesized through the high temperature solid state reaction method. The phase composition, crystal structure, morphology and photoluminescence property of the BaLiZn3(BO3)3:Eu3+ samples are systematically investigated. The phosphor can be efficiently excited by the near ultraviolet light (NUV) of 396 nm and blue light of 466 nm, and give out red light emission at 618 nm corresponding to the electric dipole transition (5D0→7F2). The optimal doping concentration of Eu3+ ions in BaLiZn3(BO3)3 is determined to be about 3 mol%, and the concentration-quenching phenomenon arise from the electric dipole–dipole interaction. The temperature dependent luminescence behavior of BaLiZn3(BO3)3:0.03Eu3+ phosphor exhibits its good thermal stability, and the activation energy for thermal quenching characteristics is calculated to be 0.1844 eV. The decay lifetime of the BaLiZn3(BO3)3:0.03Eu3+ is measured to be 1.88 ms. These results suggest that the BaLiZn3(BO3)3:Eu3+ phosphors have the potential application as a red component in white light emitting diodes (WLEDs) with NUV or blue chips.

In conventional medium voltage Solid-State Circuit Breakers (SSCBs), series-connected semiconductor switches are used with Metal Oxide Varistors (MOVs) in parallel with each of them to extend the voltage ratings of the breakers without incurring the dynamic voltage unbalance. Besides, for isolating the faults at faster speeds, the clamped surge voltages of the MOVs are always much higher than the system voltages. For those reasons, the voltage ratings of all the switches in the SSCBs have to be overdesigned according to the surge voltage values, which causes high material costs along with nonideal conduction losses in the solid-state circuit breakers employed for medium voltage DC distribution systems. To solve this dilemma, a Surgeless Diode-Clamped Multilevel Solid-State Circuit Breaker has been proposed in this paper. It offers an ultrafast isolation speed with no significant surge voltages or dynamic unbalanced voltage across the semiconductor switches. With these attributes, the proposed SSCB can potentially use the semiconductor switches rated at lower voltages compared to conventional SSCBs and have higher efficiency along with faster isolation speed. The simulation and experimental results are presented to validate the technical feasibility and practical values of the proposed solid-state circuit breaker.

Well-defined two-dimensional (2D) cobalt oxalate (CoC2O4•2H2O) nanosheets exhibit more excellent property than common bulk cobalt oxalate due to high specific surface areas and high-efficient transport of ion and electron. However, the delicate control of the 2D morphology of CoC2O4•2H2O during their synthesis remains challenging. Herein, 2D CoC2O4•2H2O nanosheets (M1), grown by straightforward chemical precipitation, can be tuned from three-dimensional (3D) structure during their synthesis with no templates or capping agents. This control is obtained by rationally changing the ratio of reactants with ethylene glycol as solvent. Moreover, Co3O4/CoC2O4 composites (M1-250) have been fabricated through low-temperature thermal treatment of the M1 precursor in air, which possess porous surfaces with the 2D morphology maintained. Benefiting from the porous surfaces, more redox-active sites and better electrical conductivity of Co3O4, the constructed M1-250//AC aqueous device manifest improved kinetics of the electrochemistry process with energy density of 27.9 Wh/kg at 550.7 W/kg and good cycling stability with sustaining 73.0 mAh/g after 5000 cycles.

It is of significance to investigate deeply the hydrodynamic features of the bubble contaminated by impurities in view of the fact that the industrial liquid is difficult to keep absolutely pure. On the basis of the finite volume method, the bubble interface contaminated by the surfactant (1-pentanol) is achieved through solving the concentration transport equations in liquid and along the bubble interface, and solving the absorption and desorption equation at the bubble interface. And the three-dimensional momentum equation is solved at the same time. It is investigated in detail on the influence of interfacial contamination degrees (described with the cap angle θ) on hydrodynamic characteristics of the spherical bubble when the bubble Reynolds number (Re) is larger than 200. The θ is realized by changing the surfactant concentration (C0) in liquid. The present results show that the hydrodynamic characteristics, such as interfacial concentration, interfacial shear stress, interfacial velocity and wake flow, are related to both Re and C0 for the contaminated bubble. When C0 is relatively low in liquid (i.e., the contamination degree of the bubble interface is relatively slight), the hydrodynamic characteristics of the bubble can still keep the 2D features even if Re>200. The decrease of θ or the increase of Re can promote the appearance of the unsteady wake flow. For the present investigation, when Re>200 and θ≤60°, the hydrodynamic characteristics of the bubble show the 3D phenomena, which indicates that axisymmetric model is no longer valid.

Sintering additives and micro-powder injection molding offer an effective method to densify boron carbide (B4C) and make B4C components with complex shapes. By adjusting the proportion of three kinds of powders (SiC, Al2O3 and Y2O3), four kinds of sintering additives were prepared. The feedstock uniformity, debinding behavior, phase composition and microstructure of micro injection molded B4C components with different sintering additives were studied. The results showed that the defects such as lattice distortion and vacancy were introduced into ball milling, which increase the surface energy and benefit subsequent sintering densification. The feedstock had good uniformity and rheology that met the requirements of micro powder injection molding. After debinding, B4C components had enough strength and showed certain sintering characteristics. The addition of sintering additives was beneficial to densification and sintering temperature reduction. The addition of sintering additives formed a second phase in the B4C crystal and at the grain boundary of B4C crystal, which changed the fracture mode from transgranular fracture to mixed fracture mechanism with transgranular fracture.

It remains challenging to synthesize supertough thermoplastic elastomers (TPEs) since the stretchability and tensile strength are mutually exclusive. Here, we report a one-pot strategy for the prep...

To obtain a long-term stable operation of the hollow fiber membrane for using in membrane contact absorption of carbon dioxide (CO2), hybrid polyvinylidene fluoride-silica-hexadecyltrimethoxysilane (PVDF-SiO2-HDTMS) membrane were fabricated via the non-solvent induced phase-inversion method. The surface properties, performance characteristics and long-term stable operation performance of the prepared membranes were compared and analyzed. The results show the outer surface of the prepared membranes exhibited superhydrophobicity because of the formation of rough nano-scale microstructures and the low surface free energy. Due to the addition of inorganic nanoparticles, the mechanical strength of PVDF-SiO2-HDTMS membranes were improved. The long-term stable operation experiments were carried out with the inlet gas (CO2/N2 = 19/81, v/v) at a flow rate of 20 mL/min and the absorbent liquid (1 mol/L DEA) at a flow rate of 50 mL/min. And the result showed that the mass transfer flux of PVDF-SiO2-HDTMS membrane decreased from the initial value of 2.39×10-3 mol/m2s to 2.31×10-3 mol/m2s, which was a decrease of 3% after 20 days. The main benefit is the addition of inorganic nanoparticles, which have strong chemical resistance and high hydrophobicity, thereby preventing structural damage and pore wetting of the membrane. PVDF-SiO2-HDTMS membrane exhibits excellent long-term stable operation performance of CO2.

Highly active and durable electrocatalysts towards oxygen reduction reaction (ORR) are imperative for the commercialization application of proton exchange membrane fuel cells. By manipulating ligand effect, structural control, and strain effect, we report here the precise preparation of Mo-doped Pt3Co alloy nanowires (Pt3Co-Mo NWs) as the efficient catalyst towards ORR with high specific activity (0.596 mA cm−2) and mass activity (MA, 0.84 A mg−1Pt), much higher than those of undoped counterparts. Besides activity, Pt3Co-Mo NWs also demonstrate excellent structural stability and cyclic durability even after 50,000 cycles, again surpassing control samples without Mo dopants. According to the strain maps and DFT calculations, Mo dopants could modify the electronic structure of both Pt and Co to achieve not only optimized oxygen-intermediate binding energy on the interface but also increased the vacancy formation energy of Co, together leading to enhanced activity and durability. This work provides not only a facile methodology but also an in-depth investigation of the relationship between structure and properties to provide general guidance for future design and optimization.

Electrochemical nitrogen reduction reaction (NRR) has been identified as a prospective alternative for sustainable ammonia production. Developing cost-effective and highly efficient electrocatalysts is critical for NRR under ambient conditions. Herein, the hierarchical cobalt-molybdenum bimetallic sulfide (CoS2/MoS2) flower-like heterostructure assembled from well-aligned nanosheets has been easily fabricated through a one-step strategy. The efficient synergy between different components and the formation of heterostructure in CoS2/MoS2 nanosheets with abundant active sites makes the non-noble metal catalyst CoS2/MoS2 highly effective in NRR, with a high NH3 yield rate (38.61 μg h–1 mgcat.–1), Faradaic efficiency (34.66%), high selectivity (no formation of hydrazine) and excellent long-term stability in 1.0 mol L–1 K2SO4 electrolyte (pH=3.5) at − 0.25 V versus the reversible hydrogen electrode (vs. RHE) under ambient conditions, exceeding much recently reported cobalt- and molybdenum--based materials, even catch up with some noble-metal-based catalyst. Density functional theory (DFT) calculation indicates that the formation of N2H* species on CoS2(200)/MoS2(002) is the rate-determining step via both the alternating and distal pathways with the maximum ΔG values (1.35 eV). These results open up opportunities for the development of efficient non-precious bimetal-based catalysts for NRR.

CO2 electroreduction reaction (CO2RR), combined with solid oxide electrolysis cells (SOECs), is a feasible technology for the storage of renewable electric energy, while its development is limited by the catalytic activity and stability on cathodes. Here, a novel garnet oxide (Gd3Fe5O12) cathode is designed, where the garnet oxide is converted to perovskite oxide and iron via in situ electrochemical phase transition during CO2 electroreduction, resulting in high activity with Faradaic efficiency close to 100% and great stability over 1000 h galvanostatic test. A variety of experimental characterizations and density functional theory calculations indicate that in situ exsolved Fe clusters can effectively enhance the adsorption energies of intermediates and lowering the CO2 dissociation barriers. Microkinetic modelling confirms that CO2RR goes through a dissociative adsorption mechanism and the electronic transfer for CO2 dissociation is the rate-determining step.

The volume of fluid (VOF) method combined with the adaptive grid method is used to study the influence of shear-thinning liquid viscosity ratio (e=μ0/μ∞) for various values of rheological index (n) and characteristic time (λ) on bubble shape, rise velocity, and apparent viscosity around a bubble; where 1/λ represents the shear rate at which the change in the viscosity curve occurs from the low shear rate to the power-law region. The present results show that, depending on the magnitudes of n and λ, the bubble shape and deformation parameter are strongly related to e, and the bubble shape can exhibit both stable and unstable states. There are two types of deformation phenomena for the unsteady deformation of bubbles. First, the aspect ratio changes with time, whereas the shape remains similar throughout. Second, the shape changes periodically with time. For the given values of n and λ, the bubble rise velocity at large time shows a nonlinear increase as e increases from 10 to ∞. Under the conditions of n≤0.3, λ*≥68.6, and e≥100 (λ*is the dimensionless characteristic time), a viscosity blind region (a region of high viscosity, where e is close to 1) appears behind the bubble. It is found that the tendency for the viscosity blind region is to reduce the bubble rise velocity at large time.

Flexible quasi-solid zinc-ion batteries (ZIBs) have large potential in power applications due to the low price, wearable nature, safety, and high capacity. However, the use of transition metal sulfide cathodes in ZIBs has not been studied extensively and the underlying mechanism and theoretical basis of this type of batteries are not well understood. Herein, a highly active cobalt-doped Ni3S2 porous nanocone framework (C12NS) is designed and demonstrated as a zinc-ion battery electrode. First-principles calculation and experiments reveal that the cobalt dopant improves the battery properties greatly. The assembled flexible zinc-ion battery exhibits a high specific capacity of 453.3 mAh g−1 at a current density of 0.4 A g−1 in as well as excellent cycling stability as manifested by a capacity retention ratio of 89.5% at a current density of 4 A g−1 after 5000 cycles. The peak energy density of 553.9 Wh kg−1 is also superior to those of most recently reported NiCo-based zinc-ion batteries. More importantly, the flexible battery can be operated under severe mechanical bending and even continues to work after physical puncturing without showing leakage. These exciting results not only reveal a novel design of cathode materials for zinc-based batteries, but also suggest their immense commercial potential in portable and wearable electronics.

The singular change of the order parameter at the first order martensitic transformation (MT) temperature restricts the caloric response to a narrow temperature range. Here the MT is tuned into a sluggish strain glass transition by defect doping and a large elastocaloric effect appears in a wide temperature range. Moreover, an inverse elastocaloric effect is observed in the strain glass alloy with history of zero-field cooling and is attributed to the slow dynamics of the nanodomains in response to the external stress. This study offers a design recipe to expand the temperature range for good elastocaloric effect.

In this research, a series of hollow glass powder (HGP) reinforced magnetorheological plastomers (MRPs) were prepared to improve the impact resistance of the materials, and the dynamic compressive properties of MRPs under high strain rate were investigated by using a split Hopkinson pressure bar (SHPB) system equipped with a customized magnetic device. Experimental results showed the HGPs greatly enhanced the yield stresses of the MRPs. Especially, for MRPs with 9 vol.% carbonyl iron powders (CIPs), the magnetic-induced yield stress increased from 7.3 MPa to 17.1 MPa (134% increased) by adding 18 vol.% HGPs. The particle structures in MRPs were further simulated and the corresponding intergranular stress was calculated to study the enhancement effect of HGPs. The simulated results showed that more compact structures were formed with the excluded volume caused by secondary HGPs, so the yield stresses of the MRPs increased under a magnetic field. However, when the mass ratio of HGP to CIP was larger than 0.67, HGPs would hinder the formation of chain-like structures and reduce the magneto-mechanical properties. As a result, the replacing of CIPs by HGPs was proven to be an excellent strategy to improve the dynamic properties of MRPs.

Energetic materials have extremely high volumetric and specific energy densities, making them attractive and important in combustion systems. To improve their combustion performance, reliable temperature acquirement method is highly demanded. A laser sensor was developed for in situ and quantitative measurements of gas temperature. Scanned-wavelength direct absorption spectroscopy was used for line-of-sight temperature measurements. Multiple absorption features in the near-infrared combination band (v1+v3) and mid-infrared fundamental band (v3) were selected to establish four absorption line pairs with good temperature sensitivity. Three infrared distributed feedback lasers (DFB) were used to cover the selected absorption lines. The accuracy and uncertainty of the sensor were first numerically evaluated in a wide temperature range of 1000–3000 K under different Gaussian white noise levels (5–20%). A free-space optical setup was established to experimentally evaluate the sensor performance by measuring benchmark laminar premixed flames, which were compared with additional thermocouple measurements, chemical kinetic modeling and computational fluid dynamics simulations. The good performance of the current sensor indicates the potential of being used in non-intrusive, in-situ and quantitative diagnostics of the energetic materials combustion.

In this study, the hexagonal NaYF4:Yb3+/Ho3+/Ce3+ microcrystals were synthesized controllably, and upconversion luminescence excited at 940 nm and its application in temperature-responsive anti-counterfeiting are reported. It is clarified that the Ln3+ (Ln = Y + Yb + Ho + Ce) density ratio of bottom plane to side plane in the unit cell can be regulated by Ce3+ doping. It is also proved that the energy transfer of Yb3+ to Ho3+ is responsible for the activation of Ho3+ under 940 nm excitation, while the cross relaxation between Ho3+ and Ce3+ participates in the redistribution of electron population of 5S2/5F4 and 5F5 levels. Both theory and experiment confirm that the intensity ratio of red to green emission (IR/IG) as a function of temperature as an independent variable has good linear characteristics in the temperature range of 300–500 K. Due to the good responsiveness of multicolor luminescence to temperature, the hexagonal NaYF4:Yb3+/Ho3+/Ce3+ with tunable morphology is a promising candidate for advanced temperature-responsive upconversion anti-counterfeiting. Our results provide a new pathway for the controllable synthesis of hexagonal NaYF4 microcrystals as well as the regulation of upconversion luminescence that is excited by wavelengths other than 980 nm and its application in anti-counterfeiting.

Red phosphorus (RP) has a suitable energy band structure and excellent photocatalytic properties. However, there are some problems, such as low quantum efficiency and serious photogenerated electron-hole recombination. The S-scheme heterostructure shows great potential in facilitating the separation and transfer of photogenerated carriers and obtaining strong photo-redox ability. Herein, hydrothermally treated red phosphorus (HRP) was combined with Bi2O2CO3 to construct Bi2O2CO3/HRP S-scheme heterojunction composite. The Bi2O2CO3 content was optimized, and the 5%Bi2O2CO3/HRP composite obtained at 5%Bi2O2CO3 mass fraction exhibited the strongest photoreduction ability. The Cr(VI) photoreduction and photolytic hydrogen production rates were as high as 0.22 min-1 and 157.2 μmol•g-1 •h-1, which were 7.3 and 3.0 times higher than those of HRP, respectively. The promoted photocatalytic activity could be attributed to the formation of S-scheme heterojunctions, which accelerated the separation and transfer of useful photogenerated electron-hole pairs, while enhancing the recombination of relatively useless photogenerated electron-hole pairs, thereby resulting in the highest photocurrent density (17.3 μA/cm2) of the 5%Bi2O2CO3/HRP composite, which was 1.6 and 4.3 times higher than pure Bi2O2CO3 (10.5 μA/cm2) and pure HRP (4.0 μA/cm2), respectively. This work would provide an advanced approach to enhance the photocatalytic activity of RP.

Lead-free ceramic capacitors have the application prospect in the dielectric pulse power system due to the advantages of large dielectric constant, lower dielectric loss and good temperature stability. Nevertheless, most reported dielectric ceramics have limitation of realizing large energy storage density (Wrec) and high energy storage efficiency (η) simultaneously due to the low breakdown electric field (Eb), low maximum polarization and large remanent polarization (Pr). These issues above can be settled by raising the bulk resistivity of dielectric ceramics and optimizing domain structure. Therefore, we designed a new system by doping (Bi0.5Na0.5)0.7Sr0.3TiO3 into 0.9NaNbO3-0.1Bi(Ni0.5Zr0.5)O3 ceramics, which simultaneously obtained a higher bulk resistivity by decreasing the grain size and achieved a smaller Pr by optimizing domain structure, thus the better Eb of 530 kV/cm and Wrec of 6.43 J/cm3 were achieved, η was improved from 34% to 82%. Besides, the 0.4BNST ceramics show excellent temperature, frequency and fatigue stability under the conditions of 20–180 °C, 1–100 Hz and 104 cycles, respectively. Meanwhile, superior power density (PD = 107 MW/cm3), large current density (CD = 1070 A/cm2) and discharge speed (1.025 μs) were achieved in 0.4BNST ceramic. Finally, the charge-discharge performance displayed good temperature stability in the temperature range of 30 °C–180 °C. The above results indicated that the ceramics have potential practical value in the field of energy storage capacitor.

To preferably regulate the charging current and decrease circuit complexity for parallel charging, a battery charger with variable charging current (VCC) and automatic voltage compensation (AVC) controls is presented. Based on the battery voltages, the VCC control not only dynamically maximizes the charging currents in both the trickle current (TC) and constant current (CC) stages but also prevents from damaging multiple batteries. Thus, the VCC control realizes safe charging and reduces charging time for parallel battery packs in the TC and CC stages. Owing to the battery’s parasitic resistance, a conventional charger changes from CC to constant voltage (CV) stage without approaching the rated voltage of the battery packs. The AVC control estimates the parasitic resistance and determines the proper transition timing from the CC to CV stage. Therefore, the duration of CC stage is prolonged and the CV charging time is reduced. Thanks to the VCC and AVC controls, the proposed battery charger can achieve charging time reduction and charging safety simultaneously. The experimental results verify that the periods of CC and CV stages are extended and shortened, respectively, and charging currents are maximized to the predefined values in the TC and CC stages. The maximum efficiencies in the CC and CV stages are up to 96.4%. Furthermore, compared to charging dual battery packs with conventional control, the proposed controls can save about half of total charging time.

Although the electromagnetic-coupling chemical vapor infiltration (E-CVI) has been proven of a high-efficiency technique for producing carbon fiber reinforced pyrocarbon (PyC) matrix (C/C) composites, a deep understanding of the deposition kinetics and mechanism of PyC matrix is still lack. In this work, a deposition model with uniform electric field but gradient magnetic field was set up by using unidirectional carbon fiber bundles as the substrates to investigate the deposition kinetics and mechanism. Meanwhile, the polarizability, and the chemical adsorption and dehydrogenation barriers of hydrocarbon were simulated based on the density functional theory (DFT) and the Climb-image nudged elastic band method, respectively. The E-CVI process exhibited extremely high PyC deposition rates of 8.7, 11.5, 16.5 and 22.7 nm/s at 700, 750, 800 and 850 °C, respectively, together with a significantly low apparent activation energy of 57.9 kJ/mol within the first 5 min. The PyC deposited at different temperatures with different time shows a smooth laminar structure with low coherent length and graphitization degree. The theoretical calculation and simulation results indicated that the electrons existing on the carbon fibers and the accelerated motion of radicals with preferred orientation forced by the derived magnetic field have reduced the energy barrier for the deposition process, thereby resulting in low apparent activation energy and high PyC deposition rate. The results of this work may shed a light on how to better direct the preparation of C/C composites by E-CVI process with high quality and efficiency.

Controlling the size of nanocrystals and inhibiting their agglomeration are of paramount importance for achieving ideal catalytic performance. Here we discovered that carbon dots (CDs) are not only able to serve as reductants but also as stabilizers of ultrasmall Co9S8 nanocrystals by means of their surface terminal groups. As a result, ultrasmall Co9S8 nanocrystals are incorporated into porous carbon nanosheets formed by splicing CDs. The resultant nanocomposites display a rich pore structure accompanying with large specific surface area and outstanding bifunctional performances to mimic the catalytic activity of peroxidase and oxidase without exerting any external energy. More importantly, the unique architecture endows Co9S8 nanocrystals with high stability and good durability. The nanocomposites have been demonstrated as a colorimetric sensor for detection of ascorbic acid with a superior anti-interference ability as well as a detection limit of 0.2 μM. Our findings open new synthetic opportunities by tuning the interaction of CDs with the surrounding environment and enable advanced applications such as biomedicine and catalytic transformations.

Nowadays, the fabrication of robust and earth-abundant hydrogen evolution electrocatalysts with noble-metal-like catalytic activities is still facing great challenges. In this report, nanorod (NR)-shaped nickel sulfide (NiS) is successfully decorated on graphene (Gr) by utilizing carbon cloth (CC) as a substrate (NiS-Gr-CC). Benefiting from the NR morphology and strong interfacial synergetic effect between NiS and Gr, the NiS-Gr-CC electrocatalyst shows good catalytic activity for hydrogen evolution reaction (HER). Specifically, the low Tafel slopes of 46 and 56 mV dec-1 along with the small overpotentials of 66 and 71 mV at 10 mA cm-2 are obtained in the acidic and alkaline electrolytes, respectively. Density functional theory results indicate that the combination of NiS and Gr can optimize the adsorption energy of H* during the HER process. The long-term durability measurement result reveals that our NiS-Gr-CC heterostructure has good electrocatalytic cycling stability (∼ 80 h) in both acidic and alkaline electrolytes. These results confirm that the NiS-Gr-CC heterostructure is a promising candidate for hydrogen evolution electrocatalyst with high catalytic activity.

Integrating the merits of long lifespan and excellent energy as well as power densities, potassium-ion hybrid capacitors (PIHCs) exhibit great prospects for future energy storage devices. To boost comprehensive performance of PIHCs, heteroatom-doping and morphology-tuning as two comprehensive strategies have been devoted to designing uniquely structural carbon-based materials with favorable advantages. An ideal strategy for simultaneous atomic doping and structural regulation is expected to be developed. Herein, we propose a novel “Killing Two Birds with One Stone” strategy to prepare a tri-elements doped hollow carbon sphere (TED-HCS) as PIHCs anodes, that is, a single template of spherical CoP particles is rationally adopted, which not only provides both a P source for heteroatom-doping but also acts as a self-sacrificial template for hollow-structure engineering. The multifunctional TED-HCS presents a high capacity of 473.0 mAh g−1 and excellent rate performance of 212.5 mAh g−1 at 5.0 A g−1. Remarkably, the as-assembled PIHCs show outstanding energy/power density (40.4 Wh kg−1/10500 W kg−1) and remain high-capacity retention of 89.15% even cycling 12,000 times. The “Killing Two Birds with One Stone” strategy offers new insight into the search for the preparation of carbon-based materials with multi-elements doping and specific morphology structure.

Photocatalytic membrane is attracting a great deal of current attention for water decontamination by taking the full advantage of photocatalysis and membrane separation. Herein, the well-defined WO3 nanoplates are homogeneously dispersed onto the surface of multilayer Ti3C2 MXene to create a novel 2D/2D nanohybrid with various Ti3C2 contents (3–7 wt%) through a facile and cost-effective approach, and then photocatalytic membrane system is developed by anchoring these heterostructured-photocatalysts on polyvinylidene fluoride (PVDF) membrane by means of vacuum filtration. Ti3C2/WO3/PVDF photocatalytic membranes exhibit enhanced RhB degradation and cyclability, alongside with refreshing behavior under visible-light illumination. We demonstrate that the excellent electrical conductivity of Ti3C2, the formation of built-in electric field and the large interface contact area between Ti3C2 and WO3 synergetically promote the spatial charge separation and increase the surface reactive sites, which is responsible for boosting the photoreactivity and photostability. Besides, a significant high flux recovery of ∼ 94% is obtained by 5 wt% Ti3C2/WO3/PVDF membrane under visible light irradiation. This study opens possibilities to construct multi-functional and robust MXenes-based photocatalytic membrane for long-term water purification.

In this study, a refined numerical model for segmental lining of a shield tunnel, which contains detailed models of reinforcement and connecting bolts, is established using finite element software. The model is first validated by the results from a full-scale model test. Then, based on the load-structure method, this numerical model is adopted to investigate the internal force distribution and the transverse deformation characteristics of the shield tunnel when it is subject to local soil loosening. The influence of loosening position, loosening range, and loosening extent on the mechanical response is extensively studied through comprehensive numerical analyses. The results show that the main influence of local soil loosening on the ring is to disturb the force balance and change the constraint conditions, thus changing the deformation pattern and force state. After the loosening occurs, the bending moment of the ring in the loosening range increases and the axial force decreases. The vertical convergence of the ring is the largest and the equivalent stiffness of the ring is the smallest when the local soil loosened at the haunch and the loosening range α is 90°. The vertical convergence of the ring increases with increasing of the loosening extent, and the equivalent stiffness decreases linearly with increasing of the loosening extent. The results can enhance our understanding of mechanical behaviors of segmental lining associated soil loosening, and will show a possible way for detecting soil loosening based on the measured deformation and internal forces.

The machining of silicon carbide (SiC) ceramic matrix composites is a significant challenge because of the severe material damage that may occur during material removal, which might shorten the service life of the composite parts. In this study, the effects of different fibre orientations of two-dimensional woven carbon-fibre-reinforced silicon carbide matrix composites (2D-Cf/SiC) on the grinding force, surface roughness, and surface/subsurface micromorphology were investigated to clarify the material removal and breakage mechanism in ultrasonic-assisted grinding of ceramic matrix composites. The results show that the predominant material removal mode in ultrasonic-assisted grinding is brittle fracture. The forms of material breakage are matrix cracking, fibre fracture, fibre pull-out, interfacial debonding, and interfacial fracture. Compared with conventional grinding, the normal force, tangential force, and surface roughness in ultrasonic-assisted grinding decreased by approximately 20%, 18%, and 9%, respectively. The machining parameters significantly impacted the grinding force and surface roughness. The material removal modes varied for different fibre orientations. Ultrasonic-assisted grinding can effectively decrease the grinding force and improve the surface integrity. The findings of this study can be applied to predict the grinding force and surface integrity of 2D-Cf/SiC and contribute to the design and manufacturing of this type of material.

Hybrid supercapacitors (HSCs) with the characteristics of high energy density, long cycle life and without altering their power density need to be developed urgently. Herein, a novel dual-ion hybrid supercapacitors (DHSCs) with Ni(OH)2 nanotube arrays (NTAs) as positive electrode and V2O5 directly grown on freestanding carbon nanotubes (CNTs) as negative electrode is assembled. In charging mechanism of DHSCs, K+ are inserted into the V2O5 negative while OH– react with Ni(OH)2 positive; during discharge, the K+ and OH– are released from V2O5 negative and Ni(OH)2 positive, respectively, and return back to the electrolyte, which is quite different from traditional metal ion or alkaline supercapacitors. Because of the merits combining dual-ion mechanism and HSCs, the DHSC displays excellent capacity retention of ∼ 81.4% after 10,000 cycles, high energy density of ∼ 25.4 μWh cm−2 and high power density of ∼ 4.66 mW cm−2, indicating the potential applications in the further on flexible wearable electronics.

Macromolecule nanocrystal network and strong interfacial interaction are always beneficial to enhance the mechanical property of polymer-based nanocomposites. Poly (vinyl alcohol) (PVA), a typical biocompatible semicrystalline polymer, is an ideal candidate for preparing high performance polymer-based nanocomposites. However, the rich hydrogen bonds between PVA matrix and graphene oxide (GO) can disrupt the formation of PVA nanocrystal network. Thus, it remains a great challenge to achieve both strong and tough PVA-GO nanocomposites. Herein, by introducing a novel Janus-like amphiphilic graphene oxide (JGO), both of hydrogen bonding and interfacial crystallization have been constructed between JGO sheets and PVA matrix. Benefiting from amphiphilic interfacial interaction and the enhanced crystal network, both PVA-JGO dried films and their swollen hydrogels films show superior mechanical properties than those of traditional PVA-GO nanocomposites. PVA-JGO dried films exhibit a 264% improvement of toughness at a JGO loading of 1wt%. Meanwhile, the corresponding PVA-JGO swollen hydrogel films display simultaneous improvement of nearly 8 times increase of tensile strength and 20 times increase of toughness compared to traditional PVA-GO nanocomposite. This work indicates multiple interfacial interactions and macromolecule crystal networks can be concurrent in PVA nanocomposites by innovative modification of nanofillers, providing a new strategy to construct PVA nanocomposites with high strength and high toughness. The integration of outstanding mechanical and swelling resistance properties on PVA-JGO nanocomposite films render their promising applications, such as packaging and toughening hydrogel materials.

Hierarchical superstructures assembled by nanosheets can effectively prevent aggregation of nanosheets and improve performance in energy storage. Therefore, we proposed a facile hydrothermal method to obtain three-dimensional (3D) superstructure assembled by nanosheets. We found that the ratio of Co2+/HMTA affected the morphology of the samples, and the 3D hierarchical structures of are obtained while the ratio of Co2+/HMTA is 12:25. The hierarchical structures with sufficient interior space preserves the original sheet-like dimensional components and results in sufficient active sites and efficient mass diffusion. Hence, the 3D Co2V2O7·nH2O hierarchical structure exhibits good rate capability and high stability while as electrode materials. Meanwhile, when power density is 745.13 W/kg, the assembled CVO-2//AC shows an energy density of 47.7 Wh/kg. The work displays a facile method for fabrication of 3D superstructure assembled by 2D nanosheets that can be applied in energy storage.

Understanding the structure–property relationships in antiaromatic molecules is crucial for controlling their electronic properties and designing new organic optoelectronic materials. Here we report the design, synthesis, and characterization of three new antiaromatic molecules (Pn, n = 1–4) based on the pentalene (P) antiaromatic core, to investigate how electron-donating and electron-accepting substituents affect P1–P4 properties. As expected, the optical, HOMO and LUMO energy levels and electronic structure are greatly modulated by core substitution. Compared to the unsubstituted compound (P1), P3 and P4 containing strong electron-withdrawing units reduced antiaromaticity as assessed by nucleus-independent chemical shift (NICS) calculations compared with P2, which is functionalized with strong electron-donating units, showing that substitution strongly tunes local antiaromaticity. Organic field-effect transistors (OFETs) fabricated using these materials indicate that P2 has an average hole mobility of ∼10−4 cm2 V−1 s−1 while P3 has an average electron mobility of up to 0.03 cm2 V−1 s−1, versus FET-inactive P1. Therefore, introduction of strong π-extended electron-withdrawing or electron-donating substituents onto an antiaromatic core is an effective strategy to switch-on charge transport capacity.

The invention of printing technologies has revolutionized the manner in which information is transmitted and reproduced. In the modern era, printing technologies , which are equipped with computerized control and design methods, have become considerably efficient and effective, facilitating A significant breakthrough in the manufacture of high-performance electrochemical energy storage systems. Through careful design and execution, the components of energy storage devices, particularly electrodes, can be formulated into functional inks, enabling the use of divers materials and devices in high-performance energy storage applications. This reviewfocuses on three major printing technologies: inkjet printing, screen printing, and 3D printing, introducing the principles of each printing technology, the design and preparation of various electrode inks, and their applications in supercapacitors. Finally, the challenges and scope for the future development of printing technologies forhigh-performance supercapacitors are presented.

Ferroelectric BaTiO3/ZnO heterojunction catalysts synthesised via the sol–gel method present obvious enhancements in spontaneous polarisation-driven Fenton-like catalytic activity. In this study, the oxidative decomposition of methylene blue (MB) dye was used as a model reaction. Pure BaTiO3-activated potassium monopersulphate (PMS) could decompose up to 48% of MB dye in an aqueous solution after 40 min. MB degradation rate firstly increased and then decreased as the ZnO content of the ferroelectric BaTiO3/ZnO heterojunction materials was increased. The maximum degradation rate of 100% and good cycling stability were observed when the BaTiO3:ZnO molar ratio was 1:1. Three active species, namely, holes (h+), sulphate radicals (SO4•−) and hydroxyl radicals (OH•), were produced following the spontaneous polarisation-driven catalytic degradation of the dye. Amongst these species, h+ and SO4•− were the main active species. Enhancements in the Fenton-like catalytic activity of BaTiO3/ZnO may be attributed to the formation of semiconductor heterojunctions, which could improve the spontaneous polarisation strength of ferroelectric BaTiO3, promote the effective separation of e−–h+ pairs and accelerate PMS activation. In summary, a novel PMS activation method was developed to provide a nontoxic, efficient and environmentally friendly technology for the degradation of organic pollutants.

Traditional fluorescent materials used in anti-counterfeiting field usually exhibit monochromatic luminescence at a single-wavelength excitation, which is easily be forged by sophisticated counterfeiters. In this work, Zn2GeO4:Mn, x%Li (x=0 and 20), Zn2GeO4­NaLiGe4O9:Mn, x%Li (x=50 and 70) and NaLiGe4O9:Mn micro-phosphors with the multi-chromatic and multi-mode luminescence have been successfully synthesized via a hydrothermal approach followed by an annealing treatment. As expected that these Li+ doped Zn2GeO4:Mn and NaLiGe4O9:Mn phosphors exhibit a double peak emission including a long green afterglow (~540 nm) and a red photoluminescence (∼668 nm). By tuning Li+ doping concentrations, a gradual colour output and a tuneable afterglow duration are achieved. Particularly, the Zn2GeO4:Mn,Li and NaLiGe4O9:Mn phosphors exhibit excellent performance as security inks for printing luminescent numbers and anti-counterfeiting patterns, which shows an afterglow time-dependent or excitation wavelength-dependent luminescence colour evolution. This work proves the feasibility of Li+ doping strategy in emission tuning, which can stimulate further studies on multi-mode luminescent materials in anti-counterfeiting applications.

Lightweight nanocomposites consisting of magnetic and dielectric units aroused intensive interest as potential high performance electromagnetic wave absorbing materials. In this work, we report a facile and efficient method to fabricate (Co, SiO2)/PPy composites with tunable electromagnetic properties. The absorbing properties and effective absorbing bandwidth can be regulated by controlling the content of SiO2 in composites. The composite shows a maximum reflection loss (RL) of -65.31 dB at 11.12 GHz with a thickness of 3.002 mm when SiO2 being 22 wt.%. The effective absorbing bandwidth reaches up to 5.1 GHz (8.91–14.01 GHz), which covers the entire X band (8–12 GHz). The improved impedance matching, high interfacial polarization and complex electromagnetic synergy in the composites are the key factors giving rise to the higher efficient absorption. The PPy aerogel-based nanocomposites with controllable absorption performance, lower density and strong environmental adaptability will become attractive candidates as advanced microwave absorbing materials.

As a typical IV-VI compound, SnTe has aroused widely attentions in the thermoelectric community due its similar crystal and band structures with PbTe. However, both the large number of inherent Sn vacancies and high thermal conductivity result in inferior thermoelectric performance in intrinsic SnTe over a broad temperature. In this work, we successfully improved those disadvantages of SnTe via stepwisely Pb heavily alloying and then In doping. A significantly wide fraction of Pb into SnTe (0–50%) achieves multiple effects: (a) the carrier concentration of SnTe is reduced through decreasing Sn vacancies via alloying high solution Pb atoms in the matrix; (b) the band structure is optimized through promoting the convergence of the two valence bands, simultaneously enhancing the Seebeck coefficient; (c) HAADF-STEM coupled with EDS results illustrate that guest Pb atoms randomly and uniformly occupied Sn atomic sites in the matrix, concurrently strengthening the phonon scattering. Furthermore, we introduced indium into Sn0.6Pb0.4Te system to create resonant states further enlarging the power factors at low-medium temperature. The integration of bands convergence and DOS distortion achieves a considerably high ZTave of ∼0.67 over the wide temperature range of 300–823 K in (Sn0.6Pb0.4)0.995In0.005Te sample.