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Aluminum (Al) powder is widely used in solid propellants. In particular, nano-Al has attracted extensive scholarly attention in the field of energetic materials due to its higher reactivity than micro-Al. However, the existence of aluminum oxide film on its surface reduces the heat release performance of the aluminum powder, which greatly limits its application. Hence, this paper used iron, a component of solid propellant, to coat micron-Al and nano-Al to improve the heat release efficiency and reactivity of Al powder. SEM, TEM, EDS, XRD, XPS, and BET were used to investigate the morphological structure and properties of pure Al and Fe/Al composite fuels of different sizes. The results show that Fe was uniformly coated on the surface of Al powder. There was no reaction between Fe and Al, and Fe/Al composite fuels had a larger specific surface area than pure Al, which could better improve the reactivity of pure Al. Besides, the catalytic effects of pure Al and Fe/Al composite fuels of different sizes on ammonium perchlorate and ammonium nitrate were explored. The results show that the catalysis of pure Al powder could be greatly improved by coating Fe on the surface of Al powder. Especially, the micron-Fe/Al composite fuel had a higher catalytic effect than the pure nano-Al powder. Hence, Fe/Al composite fuels are expected to be widely used in solid propellants.

As an innovative propulsion technique, laser augmented chemical propulsion (LACP) seems superior to the traditional ones. However, the corresponding combustion theories have still to be ascertained for LACP. Burning rate of 5-aminotetrazole (5-ATZ) propellant has been studied by testing pressed samples under different combustor pressures and laser powers. Based on micro computed tomography (MicroCT), an advanced thickness-over-time (TOT) method to characterize the regression of the produced non-planar burning surface is established. Because of a shell structure covering the combustion surface, the burning rate of the implemented 5-ATZ propellant is not constant during laser ablation. Resorting to functional fitting, a new law of non-constant burning including the effect of the observed unique burning surface structures is proposed. Accordingly, applicable combustion conditions of 5-ATZ based propellants have been preliminarily speculated for future research activities.

Breast cancer remains one of the most common cancers in women worldwide, and despite significant improvements in treatment modalities, the prognosis of this cancer is still poor. Herbs and plant extracts have been associated with various health benefits, and traditional folk medicine is still receiving great interest among patients as proven by accumulated records, tolerable side effects of herbal compounds compared to their synthetic counterparts, and low cost. Curcumin is a polyphenol identified as the main active ingredient in turmeric and has been used in the treatment of various diseases and ailments. Additionally, the pharmacological activities of curcumin on many cancers have been investigated substantially due to its ability to regulate many signaling pathways involved in cancer tumorigenesis and metastasis. However, the low solubility and bioavailability of curcumin limit its benefits, urging the need for new curcumin formulations and delivery systems. Nanotechnology has been widely publicized in cancer treatment not only to overcome the limitations of poorly soluble and physiologically unstable compounds but also to improve the delivery of the drug to the diseased site and cellular uptake. In this review, we summarized the main anti-tumor effect of curcumin and its mode of action on breast cancer and focused on the anticancer efficacy of various and recent curcumin nanoformulations and delivery systems. Such nanotechnological systems could pave the way to address a new future direction in this research area, enhancing the therapeutic potential of curcumin in the treatment of breast cancer. In the next few years, there will be more focus on developing curcumin-based materials for breast cancer treatment.

Hydroxyl-terminated polybutadiene/toluene diisocyanate (HTPB/TDI) system is widely used in composite solid propellants. The migrations of plasticizers and water molecules from solid propellants and surrounding environment to the inhibitor have always been the important issues. This study focuses on the preparation, characterization and anti-migration behavior of graphene oxide (GO)/HTPB nanocomposite liner. The GO/HTPB (GH) composite liners affect the migration of small molecules through a tighter cross-linked structure and weakening function of small molecule adsorption. The anti-migration performance of the liner at different temperatures was analyzed, and the influence of the added amount of GO on the anti-migration performance and adhesion performance was also systematically studied. The overall performance of the liner is optimized when the amount of GO filler is 0.3 wt%. After adding 0.3 wt% GO, the concentration of dioctyl sebacate (DOS) migrated into the liner is decreased by 23.28%, and the concentration of water molecules is decreased by 51.89%, indicating that the introduction of GO can significantly improve the anti-migration performance of the liner. In addition, the bond strength is greatly increased from 0.25 MPa to 0.95 MPa, which meets the application requirements of the current propellant system. This research provides an important way for the preparation of structure-function synergistic anti-migration composite liners.

Gradiently denitrated gun propellant (GDGP) prepared by a “gradient denitration” strategy is obviously superior in progressive burning performance to the traditional deterred gun propellant. Currently, the preparation of GDGP employed a tedious two-step method involving organic solvents, which hinders the large-scale preparation of GDGP. In this paper, GDGP was successfully prepared via a novelty and environmentally friendly one-step method. The obtained samples were characterized by FT-IR, Raman, SEM and XPS. The results showed that the content of nitrate groups gradiently increased from the surface to the core in the surface layer of GDGP and the surface layer of GDGP exhibited a higher compaction than that of raw gun propellant, with a well-preserved nitrocellulose structure. The denitration process enabled the propellant surface with regressive energy density and good progressive burning performance, as confirmed by oxygen bomb and closed bomb test. At the same time, the effects of different solvents on the component loss of propellant were compared. The result showed that water caused the least component loss. Finally, the stability of GDGP was confirmed by methyl-violet test. This work not only provided environmentally friendly, simple and economic preparation of GDGP, but also confirmed the stability of GDGP prepared by this method.

Polymer bonded explosives (PBXs) have high energy density, excellent mechanical properties and better thermal stability. In this study, droplet microfluidic technology was used to successfully prepare HMX/TATB microspheres. The effects of different binder types and binder concentrations on the morphology of the microspheres were studied, and results proved that NC/GAP (1:4) provides particles a regular spherical morphology and good dispersion. Subsequently, the influence of the concentration of the dispersed phase and the flow rate of the continuous phase on the particle size distribution of the microspheres was fully studied. The microspheres had narrow particle size distribution and high spherical shape. Under optimized process conditions, HMX/TATB microspheres were prepared and compared with the physical mixtures. The X-ray diffraction, differential scanning calorimetry, flow properties, bulk density, and mechanical sensitivity of the samples were also studied. Results showed that the crystal form of the microspheres remains unchanged, and the binder maintains good compatibility with explosives. In addition, the fluidity, bulk density, real density and safety performance of the microspheres are remarkably better than the physical mixture. This study provides a new method for preparing PBX with narrow particle size distribution, high spherical shape, excellent dispersion and high bulk density.

In the present study, the unique three-dimensional graphene coated nickel (Ni/C) foam reinforced silicon carbide (Ni/C@SiC) composites were first obtained via the precursor impregnation and pyrolysis (PIP) processes. The microstructure images indicated that the SiC fillers were successfully prepared in the skeleton pores of the Ni/C foam. The influence of the PIP cycles on the microwave absorption performances was researched, and the results indicated that after the primary PIP process, Ni/C@SiC–I possessed the optimal microwave absorbing performance with a minimum reflection loss(RL) of −25.87 dB at 5.28 GHz and 5.00 mm. Besides, the RL values could be below −10.00 dB from 5.88 GHz to 7.74 GHz when the corresponding matching thickness was 3.85 mm. However, the microwave absorption properties of Ni/C@SiC-II and Ni/C@SiC-III were tremendously degraded as the PIP times increased. At last, the electromagnetic parameter, dielectric loss, attenuation constant as well as impedance matching coefficient were further investigated to analyze the absorbing mechanism, which opened a new path for the certain scientific evaluation of the absorbing materials and had extremely important to the defence technology.

In this study, using a solution casting process, thermoplastic polyurethane elastomer (TPU) composites containing different contents of lead zirconate titanate (PZT) ferroelectric particles were produced. The damping treatment of composites at high volume of fillers was investigated. SEM micrographs showed that PZT particles had a proper distribution in the PU matrix. Differential scanning calorimetry (DSC) thermograms indicates that melting enthalpy decreases by raising PZT filler content. The results of the dynamic mechanical thermal analysis (DMTA) proved that the magnitude of loss factor (tan δ) strongly depends on PZT content, and it decreased from 0.51 to 0.27 as PZT content increased. The value of E0 increases to 0.32 GPa in the composite reinforced with 50 v% of PZT. The role of PZT on the acoustic behavior of TPU was measured using the acoustic absorption coefficient (a). The results showed that as PZT content increased from 0 to 50%, the acoustic absorption coefficient reached 0.25 at 6000 Hz frequency. The composites of PZT/PU with 0–3 connectivity were poled, and the optimal poling conditions that could be applied without sample breakdown were studied. Moreover, we prepared composites containing 70 vol% PZT particles by modifying the particles. Modification of PZT particles caused a decrease in both d33 and g33 constants of the PZT/PU composites.

Fragments and blast waves generated by explosions pose a serious threat to protective structures. Experiments have shown that the single ballistic resistance or blast resistance of the steel plate improves significantly after coating polyurea. However, the dynamic response and structural design for the polyurea-coated structure under the combined fragments and blast loading are still lacking. In this paper, the impact resistance of polyurea-coated steel plate under complex dynamic loading is analyzed and designed for improving comprehensive ballistic and blast resistance using the newly established computational evaluating model. Firstly, according to the thickness and placement effects of the coating on the ballistic and blast resistance, the steel-core sandwich plates are designed, which are proved to own outstanding comprehensive ballistic and blast resistance. Besides, the distribution diagram of ballistic and blast resistance for different polyurea-coated steel plates is given to guide the design of protective structures applying in different explosion scenarios. Furthermore, the dynamic response of designed plates under two scenarios with combined fragments and blast loading is studied. The results show that the synergistic effect of the combined loading is significant. It reduces both the ballistic and blast resistance of the polyurea-coated steel plate and causes a more severe failure than the sum of the failures induced by the individual fragments and blast impact. Besides, the acting sequence of the fragments and blast affects the structural protective performance heavily. It is found that the first loading inducing structural large deformation or damage generally is dominant. In the scenario of fragments penetrating firstly, the excellent unit-thickness ballistic performance of the structural front part is strongly needed for improving the comprehensive ballistic and blast resistance. The analysis of dynamic response and structural design for the polyurea-coated steel plate in this paper will be helpful for designing lightweight protection structures with excellent comprehensive ballistic and blast resistance.

This paper presents an experimental investigation on the durability properties of metakaolin (MK) and bottom ash (BA) blended geopolymer under different environmental exposure. The blended geopolymer concrete (GPC) was prepared with sodium based alkaline activators under ambient curing temperature. The concentration of sodium hydroxide used was 8 M. The ratio of sodium silicate to sodium hydroxide was kept as 2.0. The performance of blended geopolymer concrete was compared with conventional concrete (CC). The test results reveal that blended geopolymer concrete develops a better performance against sulphate and acid resistance. Also, MK-BA GPC shows enhanced performance over the conventional concrete in terms of sorptivity, rapid chloride and water absorption.

In view of the difficulty of kerosene-air detonation faced by the application of rotating detonation to aviation engines, in order to improve the kerosene detonation activity, the atmospheric pressure gliding arc plasma is used to conduct secondary adjustment of the pre-combustion cracking products. The results show that the components with larger molecular weight in the pre-combustion cracking products, such as ethylene and methane, can be cracked into highly active species of hydrogen and acetylene by gliding arc plasma. With the increase of the fuel ratio of pre-combustion cracking, the plasma has a more significant effect on the adjustment of high active components. However, as the flow rate of the cracking gas treated by plasma increases, the adjustment effect is obviously reduced.

An adverse effect resulting from explosive mine blasts is the production of toxic nitrogen oxides (NO and NO2) and carbon monoxide (CO). The empirical measurements of the concentration of toxic gases showed that it depends not only on the composition of an explosive and properties of its ingredients but also on several other parameters, such as volume of blasting chamber, explosive charge mass and design, confinement characteristics, surrounding atmosphere, etc. That explains why measured concentrations of toxic gases reported in literature significantly differ. In this paper, we discuss the possibility of theoretical prediction of the concentration of toxic gases by thermochemical equilibrium calculation applying two models: ideal detonation model and deflagration model. It can be demonstrated that thermochemical calculations can provide a good estimation of the measured concentrations and reproduce experimentally obtained effects of additives on the production of toxic gases. It was also found that the ideal detonation model applies to heavily confined explosive charges, while the deflagration model is more suitable for low detonation velocity explosives with light confinement.

In the bone tissue engineering field (BTE), it is of significant importance to develop bioactive multifunctional scaffolds with enhanced osteoconductivity, osteoinductivity, and antibacterial properties required for lost bone tissue regeneration. In this work, a bioactive glass-ceramic scaffold was manufactured via a novel polymer-derived ceramics (PDC) manufacturing method. To gain antibacterial properties, the silver ions were incorporated in controlled amount along with other precursors in the PDC processing stage. Microstructural and structural properties of the fabricated silicate-phosphate glass-ceramic scaffold were evaluated by scanning electron microscopy (SEM) equipped with energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD) analysis, respectively. Furthermore, bioactivity, antibacterial, and cytotoxicity evaluation of PDC scaffolds were conducted. The microstructural analysis determined that scaffolds have interconnected porous network with two different pore range size favorable for osteointegration and bone formation. The structural analysis confirmed that fabricated glass-ceramic scaffolds contain bioactive octacalcium phosphate (OCP) phase responsible for enhanced bioactivity and HCA formation during the immersing of scaffolds in simulated body fluid (SBF) for several days. Moreover, PDC scaffolds with Ag nanoparticles showed considerable antibacterial properties against Gram-negative Klebsiella pneumoniae and Gram-positive Staphylococcus aureus bacteria cells. This study has demonstrated that it is possible to develop a novel group of antibacterial and bioactive Ag incorporated silicate-phosphate glass-ceramic scaffolds for BTE applications, such that, it was verified in vivo.

Fluoride is a natural contaminant of water – that endangers many people worldwide when present in concentrations higher than 2 ppm. Here, fluoride removal by four different nanostructured colloidal particles (SiO2@ZrO2nc, SiO2@ZrO2c, @ZrO2nc, and @ZrO2c) was measured in batch systems within a period of 24 h. Surprisingly, these materials removed fluoride from the water solutions and reached equilibrium in less than 10 min. The combination of high specific surface and fast fluoride removal placed these materials among the top materials currently known in fluoride removal. Also, the impact of element leaching was measured and quantified. The influence of time, pH, and fluoride concentration on leaching of Zr and Si was evaluated with a response surface methodology. Leaching of Zr and Si continued for several hours and depended on first-order, quadratic and cross-product coefficients. Previous studies of fluoride removal with zirconium oxide often assumed that a decrease in fluoride concentration in the solution indicated that fluoride was bound to the surface of the oxide. Zirconium oxide's solubility in water is low, but not zero. Hence, Zr might have formed soluble fluorocomplexes. This is the first report of fluoride removal with zirconium oxide that studied the leaching of the solid to exclude the formation of soluble fluorocomplexes.

The design of astonishing combinations of benzoxazine resins with various fillers is nowadays of great interest for high quality products, especially in ballistic armors. The objective of this study is to investigate a new hybrid material prepared as multi-layered composite plate by hand lay-up technique. Different composites were manufactured from Kevlar fabrics reinforced polybenzoxazine, which was filled with silane treated microcrystalline cellulose (MCC Si) at various amounts in the interlayers. The developed materials were tested for their flexural, dynamic mechanical and ballistic performance. The aim was to highlight the effect of adding different amounts of MCC Si on the behavior of the different plates. Compared to the baseline, the dynamic mechanical and bending tests revealed an obvious decrease of the glass transition of 21 °C and a notable increase in storage modulus and flexural strength of about 180 %and17%, respectively, upon adding 1% MMC Si as filler. Similarly, the ballistic test exhibited an enhancement in kinetic energy absorption for which the composite supplemented with 1% MCC Si had the maximal energy absorption of 166.60 J. These results indicated that the developed panels, with interesting mechanical and ballistic features, are suitable to be employed as raw materials to produce body armor.

Development of the interplay between monomer sequence and supramolecular chemistry is critical if chemistry is to recapitulate the properties of proteins and nucleic acids in the synthetic world. We have created sequenced trimers of aromatic donor/acceptor units which participate in charge-transfer interactions, linked by phosphodiesters. Each sequence displays its own characteristic self-assembly, and moreover complementary sequences interact with each other to produce new nanostructures and emergent thermochromism. This finding paves the way towards new functional nanomaterials which make bio-analogous use of sequence to tune structure.

In the present work, samples of barium borate glasses containing different molar ratios of ZnO were prepared using the conventional melt-quenching technique. X-ray diffraction studies confirmed the amorphous nature of the studied materials. Structural analysis using FT-Infrared confirmed the incorporation of the Zn atom in the glass matrix as a ZnO4 unit and the existence of ZnO in the tetrahedral interstitial sites. TEM images for the studied materials show that the average particle size is about 20 nm and the ZnO4 structural units reside in the glass matrix with high homogeneity. Density and molar volume studies manifested an increase in the density as the amount of ZnO increases and a subsequent decrease in the molar volume. UV absorption studies showed a blue shift in the absorption peak from 343 nm to 315 nm. Additionally, an observed reversible behavior around 338 nm divides the absorption range into high energy and low energy regions. In the high energy region, both absorbance, absorption coefficient, and refractive index increased with ZnO content increment. In the low energy region, this behavior was reversed, and the calculated values of the refractive index agreed with the measured ones in this region. Studies of optical dielectric parameters showed a Debye-type relaxation process in which increasing the ZnO content shortens the sample relaxation time. Our results, collectively, suggest the studied materials for several optoelectronic device applications such as high-energy optical filters, optical switches, and frequency converters.

As an essential component of ammunition, pyrotechnics can control ignition with high reliability. However, due to limits of fabrication technology, traditional pyrotechnics are bulky. To achieve both functionality and miniaturization, MEMS pyrotechnics integrate initiator, safety-and-arming (S&A) device and lead charge and keep all components within a small size. MEMS S&A devices, as the core component to ensure system safety, are difficult to achieve active and rapid response to control signals with high safety and reliability. In order to overcome the difficulty, we propose the design and characterization of a MEMS pyrotechnic with a double-layer barrier S&A device. The MEMS pyrotechnic is a high-integrated device with an overall size of 13.4 × 8.5 × 5.2 mm3. The initiator is a NiCr bridge foil covered with an Al/CuO energetic film, which can generate flame when ignited by an excitation voltage. To match the flame energy, lead styphnate is chosen in this study as the lead charge. The S&A device contains four semi-circular barriers, which are directly driven by V-shape electro-thermal actuators to gain active control of the pyrotechnics' ignition condition with rapid response. To improve the system's reliability, the four barriers are axisymmetrically placed in two layers, two barriers for each layer, to constitute a double-layer structure with a thickness of 100 μm. The ignition test results show that the S&A device can prevent the initiator from detonating the lead charge in safety condition. In arming condition, the lead charge will be detonated.

To improve the safety of HMX, HMX/NH2-GO composite was prepared with aqueous ammonia functionalized graphene oxide (NH2-GO). The composite was characterized by SEM, Zeta potential, XPS, Raman spectrum, XRD, HPLC, DSC and BAM sensitivity test. The results indicated that the functionalization with aqueous ammonia can enhance the interaction between GO and HMX, and more efficiently desensitize the explosive. The optimal impact sensitivity of the HMX/NH2-GO composite can be not less than 40 J, which is also the most insensitivity compared to the previous reports prepared by coating desensitization with non-energetic desensitized material. Moreover, the potential reason for the different impact and friction sensitivity was also discussed, which may bring a novel perspective to achieve the desensitization of energetic material.

The monolithic foamed propellants with high densities were prepared by casting and two-step foaming processes. Glycidyl azide polymer (GAP) and isocyanate were used as the binder system and 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (HNIW, CL-20) was employed as the energetic component. The newly designed formulation containing 60 % CL-20 produced a force constant of 1077 J/g and low flame temperature of 2817 K. Two foamed propellants with densities of 1.32 g/cm3 and 1.53 g/cm3 were fabricated by a confined foaming process and examined by closed bomb tests. The results revealed that porosity significantly affects burning performance. A size effect on combustion behaviors was observed for the foamed propellant with 5.56 % porosity, and a double-hump progressive dynamic vivacity curve was obtained. At last, the 30 mm gun test was carried out to demonstrate the interior ballistic performance, and the muzzle velocity increased by 120 m/s at the same maximum chamber pressure when monolithic propellant was added in the charge.

Improving the thermal decomposition performance of hexanitrohexaazaisowurtzitane (CL-20) by appropriate methods is helpful to promote the combustion performance of CL-20-based solid propellants. In this study, we synthesized a sandwich structure of CL-20 and nanoporous carbon scaffolds film (NCS) and emphatically studied the thermal decomposition performance of the composite structure. Thermogravimetric analysis and differential scanning calorimetry were used to measure the thermal decomposition process of the composite structure. The kinetic parameters of thermal decomposition were calculated by the thermal dynamic analysis software AKTS. These results showed that the thermal decomposition performance of the sandwich structure of CL-20 and NCS was better than CL-20. Among the tested samples, NCS with a pore size of 15 nm had the best catalytic activity for the thermal decomposition of CL-20. Moreover, the thermal decomposition curve of the composite structure at the heating rate of 1 K/min was deconvoluted by mathematical method to study the thermal decomposition process. And a possible catalytic mechanism was proposed. The excellent thermal decomposition performance is due to the sandwich structure enhances the interface reaction of CL-20 and NCS. This work may promote the extensive use of CL-20 in the field of solid rocket propellant.

To improve the thermal properties of aluminum (Al) in the energetic system, a coated structure with ammonium perchlorate (AP) was prepared by a facile approach. And N, N-Dimethylformamide (DMF) was chosen as an ideal solvent based on heterogeneous nucleation theory and molecular dynamics simulation. This coated structure could enlarge the contact area and improve the reaction environment to enhance the thermal properties. The addition of AP could accelerate oxidation temperature of Al with around 17.5 °C. And the heat release of 85@15 composition rises to 26.13 kJ/g and the reaction degree is 97.6% with higher peak pressure (254.6 kPa) and rise rate (1.397 MPa/s). An ideal ratio with 15 wt% AP was probed primarily. The high energy laser-induced shockwave experiment was utilized to simulate the reaction behavior in hot field. And the larger activated mixture of coated powder could release more energy to promote the growth of shockwave with higher speed up to 518.7 ± 55.9 m/s. In conclusion, 85@15 composition is expected to be applied in energetic system as a novel metal fuel.

Boron is a very promising and highly attractive fuel because of high calorific value. However, the practical applications in explosives and propellants of boron have been limited by long ignition delay time and low combustion efficiency. Herein, nano-Al and graphene fluoride (GF) as surface activated materials are employed to coat boron (B) particles to improve ignition and combustion performance. The reaction heat of nano-Al coated B/KNO3 and GF coated B/KNO3 are 1116.83 J/g and 862.69 J/g, respectively, which are higher than that of pure B/KNO3 (823.39 J/g). The ignition delay time of B/KNO3 could be reduced through nano-Al coating. The shortest ignition delay time is only 75 ms for B coated with nano-Al of 8 wt%, which is much shorter than that of pure B/KNO3 (109 ms). However, the ignition delay time of B/KNO3 coated with GF has been increased from 109 to 187 ms. B coated with GF and nano-Al shown significantly influence on the pressure output and flame structure of B/KNO3. Furthermore, the effects of B/O ratios on the pressure output and ignition delay time have been further fully studied. For B/KNO3 coated with nano-Al and GF, the highest pressures are 88 KPa and 59 KPa for B/O ratio of 4:6, and the minimum ignition delay time are 94 ms and 148 ms for B/O ratio of 7:3. Based on the above results, the reaction process of boron coated with GF and nano-Al has been proposed to understand combustion mechanism.

In this study, porous carbon has been prepared through potassium hydroxide (KOH) activation of coconut fiber (CF) and subsequent carbonization in the presence of an inert gas. The activated carbons (AC) were prepared via carbonization of the precursor at different temperatures. Subsequently, their electromagnetic wave absorption (EMWA) performance was investigated at X-band frequency. The phase crystallinity, porous features, and degree of graphitization of the activated carbons were studied using XRD, nitrogen adsorption/desorption isotherm, and Raman spectroscopy, respectively. Using the BET method, the activated carbon prepared at 750 °C displayed a high specific surface area of 602.9 m2 g−1 and an average pore size of 6 nm, which confirms the extant of mesopores. The EMWA was studied using COMSOL Multiphysics software based on the finite element method. Results show that the activated carbon prepared at 750 °C attained an optimal reflection loss of −45.6 dB at 10.96 GHz with a corresponding effective bandwidth of 3.5 GHz at a thickness of 3.0 mm. In conclusion, this study interestingly shows that porous carbon obtained from coconut fiber has great potential for attenuating electromagnetic waves.

Nowadays, the mitigation of damage to a ship caused by the underwater explosion attracts more and more attention from the modern ship designers. In this study, two kinds of scale tests were conducted to investigate the effects of polyurea coatings on the blast resistance of hulls subjected to underwater explosion. Firstly, small-scale model tests with different polyurea coatings were carried out. Results indicate that polyurea has a better blast resistance performance when coated on the front face, which can effectively reduce the maximum deflection of the steel plate by more than 20% and reduce the deformation energy by 35.7%–45.4%. Next, a full-scale ship (approximately 50 m × 9 m) under loadings produced by the detonation of 33 kg of spherical TNT charges was tested, where a part of the ship was coated with polyurea on the front face (8 mm + 24 mm) and not on the contrast area. Damage characteristics on the bottom were statistically analyzed based on a 3D scanning technology, indicating that polyurea contributes to enhancing the blast protection of the ship. However, damage results of this test were different from those of the small-scale tests. Moreover, the deformation area of the bottom with polyurea was greatly increased by 40.1% to disperse explosion energy, a conclusion that cannot be drown from the small-scale tests.

The kinetics of the thermally induced glass / crystal phase transformation of chalcogenide glasses plays an important role in determining their candidacy for optical phase change memory applications. The rate of crystallization and the corresponding activation energy are the two crucial kinetic parameters that reflect the durability and quality (i.e., storage properties) of phase change materials. This script deals with metal-induced effects on thermally regulated non-isothermal crystallization in a new glass alloy of Se-Te-Sn using calorimetric measurements. The elements Antimony (Sb), Cadmium (Cd) and Indium (In) have been used as structural modifiers for this purpose. The crystallization and glass transition kinetics of these glass alloys have been investigated by thermal analysis of several kinetic parameters such as the parameter of order n, the maximum crystallization temperature Tc, the crystallization rate K and the consequent activation energy Ec). A DSC is used in non-isothermal mode for the present studies. The values of the activation energy Ec are determined using the data obtained from the displacement of the exothermic peaks of crystallization in non-isothermal DSC plots at various heating rates. The role of the additives Sb, Cd and In in the variation in the rate of crystallization K of and the Avrami index (n) for each glass alloy is also examined. Detailed thermal analysis of the kinetic data confirms the superiority of Cd over the other two additives (In and Sb) for optimization of the kinetic properties of the main SeTeSn glass.

The work addresses to the study of the molecular and crystal structure and properties of a new energy-intensive compound 3,6-bis(2,2,2-trinitroethylnitramino)-1,2,4,5-tetrazine (NBTAT), first obtained by the authors in 2020. NBTAT compound crystallizes in the monoclinic system, space group P2(1)/n, density at room temperature 1.939 g/cm3. The energies of crystal packing and pairwise intermolecular interactions in NBTAT and its unnitrated analogue BTAT were calculated, and their comparative analysis was carried out. The enthalpy of formation of NBTAT molecules was calculated by quantum-chemical methods using Gaussian 09, and the enthalpy of formation of NBTAT in the solid phase (618 kJ/mol) was estimated. The energy capabilities of NBTAT as an oxidizer of solid composite propellants are estimated. It is shown that in metal-free compositions NBTAT is significantly superior to ammonium perchlorate (AP), dinitramide ammonium salt (ADN), HMX, BTAT at all stages of rocket systems, and is comparable to the superdense CL-20 yielding to the latter at the lower stages and slightly winning at the upper stages.

Chitosan-coated Fe3O4 nanoparticles were prepared by coprecipitation followed by reaction with chitosan and different volumes of glutaraldehyde. Coating was modified by varying the volume of glutaraldehyde and reaction time. XRD pattern shows maxima compatible Fe3O4 structure. FTIR spectroscopia confirms the presence of chitosan, more evident in samples with higher chitosan content, as denoted by TGA. TEM images of samples with low glutaraldehyde content reveal particles coated with a homogeneous chitosan shell. Meanwhile, those prepared with high glutaraldehyde volume show nanoparticles dispersed in an organic matrix. Samples present almost superparamagnetic behavior with magnetization saturation values that are reduced as the content of organic matter increases. Regarding the stability of these samples in solution, the presence of a homogeneous coating improves the initial suspension, although it does not prevent its subsequent aggregation over time. However, this aggregation process is reduced for sample synthesized with 1 mL of glutaraldehyde after 6 h of reaction.

Ruthner powder is a by-product of the steel hot-rolling process. This study introduces a new application area for this waste material by investigating its activity for the oxygen evolution reaction. Ruthner powder with the α-Fe2O3 phase structure was deposited on the carbon paper substrates using the electrophoretic deposition (EPD) process to fabricate the electrodes. The effect of the concentration of cetrimonium bromide ([CTAB]) and the Ruthner powder ([RP]) in the EPD cell on the morphology and activity of the electrodes were investigated by SEM, LSV, and EIS techniques. The results revealed the formation of a homogenous layer on the carbon paper when [CTAB] and [RP] were respectively 0.4 g.l−1 and 0.2 g.l−1. The obtained electrode showed the best activity among all fabricated electrodes. In particular, its onset overpotential and overpotential at a current density of 10 mA.cm−2 were respectively 85% and 25% lower than those of bare carbon electrodes.

Nano-TATB was developed in microchannels by physical method and chemical method, respectively. The effects of total flow rate, number of microreactor plates, solvent/non-solvent ratio and temperature on the particle size of TATB in the physical method were studied. Prepared TATB were characterized by Nano Sizer, Scanning Electron Microscopy, Specific surface aperture analyzer, X-ray diffraction, Fourier transform infrared spectroscopy and Differential Scanning Calorimetry. The results show that the TATB obtained by physical method and chemical method are spherical, with average particle size of 130.66 nm and 108.51 nm, respectively. Specific surface areas of TATB obtained by physical and chemical methods are 21.37 m2/g and 21.91 m2/g, respectively. Compared with the specific surface area of micro-TATB (0.0808 m2/g), the specific surface area of nano-TATB is significantly increased. DSC test results show that the smaller the particle size of TATB, the lower the thermal decomposition temperature. In addition, by simulating the mixing state of fluid in microchannels and combining with the classical nucleation theory, the mechanism of preparing nano-TATB by microchannels was proposed.

Air contamination caused by the ammonia slip phenomenon has gradually captured the researcher's extensive attention. An effective strategy for controlling fugitive NH3 is critical to improving the air quality and living environment. In the present work, CuOx/La2Ce2O7 composite as a potential candidate catalyst is synthesized through the electrostatic adsorption method for the selective catalytic oxidation (SCO) of NH3 to N2. The 5% CuOx/La2Ce2O7 exhibits the best catalytic activity (T90 =243 ℃) and ammonia conversion efficiency. The improvement of performance is mainly attributed to the superficial connection of [Ce-O-Cu], which enhances the capturing ability of ammonia molecule and accelerates the dissociating efficiency of N-H bonding for N2 evolution, simultaneously. This work provides a facile method to synthesis pyrochlore composite catalyst of NH3-SCO for solving the problem of ammonia slip pollution in the future.

Copper azide with high density was successfully synthesized by in-situ reaction of nanoporous copper (NPC) precursor with HN3 gaseous. NPC with pore size of about 529 nm has been prepared by electroless plating using polystyrene (PS) as templates. The copper shells thickness of NPC was controlled by adjusting the PS loading amount. The effects of copper shell on the morphology, structure and density of copper azide were investigated. The conversion increased from 87.12% to 95.31% when copper shell thickness decrease from 100 to 50 nm. Meanwhile, the density of copper azide prepared by 529 nm NPC for 24 h was up to 2.38 g/cm3. The hollow structure of this NPC was filled by swelling of copper azide which guaranteed enough filling volume for keeping the same shape as well as improving the charge density. Moreover, HNS-IV explosive was successfully initiated by copper azide with minimum charge thickness of 0.55 mm, showing that copper azide prepared has excellent initiation performance, which has more advantages in the application of miniaturized explosive systems.

Polymeric biomaterials such as polylactic acid (PLA) play a prominent role in the advancement of biomedical additive manufacturing (AM). PLA offers indeed a very advantageous combination of thermo-mechanical properties and functional attributes, as it is biobased, biodegradable, biocompatible and easy to print. However, PLA can be damaged by common sterilization methods and is sensitive to most chemical disinfectants, and this may impair its widespread usage. One of the most promising ways to overcome this shortcoming is to provide PLA with embedded antibacterial activity by the addition of appropriate fillers such as ZnO nanoparticles. After a detailed introduction to the basic properties of PLA and ZnO nanoparticles, the present review analyzes the main variables that govern the antibacterial activity of PLA-ZnO nanocomposites. Current applications and related manufacturing processes are also presented to showcase the importance of having embedded antibacterial functions in demanding fields such as food packaging and wound dressing. Emphasis is then placed on the emerging literature of the AM of PLA-ZnO nanocomposites, with a focus on fused filament fabrication (also known as fused deposition modeling). Existing gaps and hurdles related to the development and 3D printing of such composites are critically discussed. It is envisioned that a deeper understanding of the processability, thermo-mechanical behavior, biocompatibility and anti-bacterial efficacy of additively manufactured PLA-ZnO nanocomposites will foster their adoption in the biomedical field and, ultimately, in all circumstances where it is crucial to limit infection transmission.

The random mobility of charge carriers is a main factor causing the low photocatalytic efficiency of g-C3N4. Thus, the controllable migration of charge carriers is a rational strategy to suppress the charge recombination and facilitate charge separation. Herein, an ethylenediamine modified g-C3N4 displays improved photocatalytic activity. The excellent charge separation efficiency is confirmed to be a key factor for the enhancement. The observation from TEM image after photo-deposited Pt nanoparticles and DFT calculations verify the accumulation of electrons on some area of surface. The increased -NH2 groups significantly tune the electronic structure of g-C3N4 after modification. The generation of midgap state also affect the charge separation. Our reports provide a simple method to manage the migration of charge carriers and enables electrons directional transfer, which suppress the recombination and improve the photocatalytic activity.

Implant-associate infection (IAI) is a major cause of failure of bone implant materials, and one of the significant challenges in clinical managements. A synergistic coating strategy combining montmorillonite (MMT) sustained release, adsorption of bacteria and gentamicin (GS) bactericidal is proposed herein to tackle infection issues. Surface morphology, microstructure and chemical composition of the samples were investigated using SEM, XRD, FT-IR and XPS. Electrochemical experiments and immersion experiments reveal that corrosion resistance of Mg samples with GS/MMT coatings was higher than that of bare Mg alloy substrate in DMEM solution. In vitro studies demonstrated that the GS/MMT coating had a significant inhibitory effect on Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). The viability of MC3T3-E1 cells was 92.7% after a co-culturing for 72 h. After a subcutaneous transplantation of 90 days, the survival rate was 100% for GS/MMT-coated Mg alloy specimens with no infection at the implantation sites and no toxic damage to liver, kidney and local muscles pathological sections. This study provides a novel method for the preparation of sustained-release antimicrobial coatings on biodegradable Mg alloys as promising candidates for orthopedic implant materials.

High velocity ballistic impact deformation behaviour of Titanium/GFRP Fiber Metal Laminates (FML) has been explored. Both single and multiple projectiles impact conditions were considered. Ti/GFRP FML targets were fabricated with addition of 5% and 10% weight percentage of boron carbide (B4C) particles. Mechanical properties of Ti/GFRP FML targets were determined as per ASTM standards. High velocity ballistic experiments were conducted using Armour Piercing Projectile (APP) of diameter 7.62 mm and velocity ranging between 350 and 450 m/s. Depth of penetration of the projectile into the target was measured. The deformation behaviour of Ti/GFRP targets with and without the presence of ceramic powder (B4C) was investigated. “Ductile hole growth” failure mode was observed for pure GFRP target when subjected to single projectile impact whereas “plugging” failure mode was noted for Ti/GFRP targets. The presence of B4C (5% by weight) particles has significantly improved the ballistic resistance of the Ti/GFRP FML target by offering frictional resistance to the projectile penetration. Further addition (10% by weight) of B4C has reduced the ballistic performance due to agglomeration. None of the targets showed ‘brittle cracking’ or ‘fragmentation’ failures. When compared to the published results of Aluminium (Al 1100/GFRP and Al 6061/GFRP) FMLs, Ti/GFRP FML showed lesser DoP which increases its potential application to aerospace industry.

In this work, a novel in situ auto-reduction strategy was developed to encapsulate uniformly dispersed Pd clusters/nanoparticles in MIL-125-NH2. It is demonstrated that the amino groups in MIL-125-NH2 can react with formaldehyde to form novel reducing groups (-NH CH2OH), which can in situ auto-reduce the encapsulated Pd2+ ions to metallic Pd clusters/nanoparticles. As no additional reductants are required, the strategy limits the aggregation and migration of Pd clusters and the formation of large Pd nanoparticles via controlling the amount of Pd2+ precursor. When applied as catalysts in the hydrogenation of phenol in the aqueous phase, the obtained Pd(1.5)/MIL-125-NH-CH2OH catalyst with highly dispersed Pd clusters/nanoparticles with the size of around 2 nm exhibited 100% of phenol conversion and 100% of cyclohexanone selectivity at 70 °C after 5 h, as well as remarkable reusability for at least five cycles due to the large MOF surface area, the highly dispersed Pd clusters/nanoparticles and their excellent stability within the MIL-125-NH-CH2OH framework.

NiFe2O4/polypyrrole (NiFe2O4/PPy) nanocomposites are prepared by a simple surface-initiated polymerization method and demonstrate negative permittivity in the low frequency regions. These nanocomposites also exhibit significantly enhanced electromagnetic wave (EMW) absorption property in the high frequency regions. Compared with pure PPy, the enhanced negative permittivity is observed in the NiFe2O4/PPy nanocomposites with a NiFe2O4 loading of 5.0, 10.0, 20.0 and 40.0 wt%, indicating the formation of metal-like electrical conducting network in NiFe2O4/PPy nanocomposites. Moreover, the negative permittivity could be tuned by changing the NiFe2O4 loading. The minimum reflection loss (RL) of -40.8 dB is observed in the 40.0 wt% NiFe2O4/PPy composites with a thickness of only 1.9 mm. The effective absorption bandwidth below -10.0 and -20.0 dB reaches 6.08 and 2.08 GHz, respectively. The enhanced EMW absorption performance benefits from the improved independence matching, EMW attenuation capacity, and synergistic effects of conduction loss, dielectric loss (interfacial and dipole polarizations) and magnetic loss (exchange and natural resonances). This research work provides a guidance for the fabrication of nanocomposites with an excellent EMW absorption.

(γ’+β) two-phase Ni-Al is a promising high-temperature protective coating material used on Ni-base superalloys since it has good interfacial compatibility with superalloys due to the low Al content compared to single-phase β-NiAl. In this paper, we aim to improve the oxidation resistance, whereby Ni-34Al-0.1Dy, a (γ’+β) two-phase Ni-Al alloy, was treated by laser shock processing (LSP) and the oxidation behavior at 1150 °C was investigated. The results showed that after oxidation, Al2O3 scale formed on the original β phase of the untreated alloy with a small grain size (200-800 nm), while for the LSP-treated samples, the scale grown on the original β phase was dominantly composed of larger Al2O3 grains with a size of 2-3 μm. The distinction was attributed to the promotion of θ-Al2O3 to α-Al2O3 transformation induced by the LSP, because the dislocation density, as well as surface roughness, were increased during LSP treatment which can provide heterogeneous nucleation sites for α-Al2O3. In addition, the larger-size Al2O3 particles, derived from the direct conversion of needle-like θ-Al2O3 in the initial oxidation stage, could rapidly overspread the whole β phase surface thus reducing the scale growth rate.

Perovskite-type oxides are considered as promising alternatives to the scarce and expensive precious metal-based electrocatalysts for oxygen evolution reaction (OER) and oxygen reduction reaction (ORR). Here, we report a Bi0.15Sr0.85Co0.8Fe0.2O3-δ (BiSCF) perovskite prepared by the conventional solid-state reaction method as a novel bifunctional oxygen electrocatalyst in alkaline media. BiSCF shows excellent electrocatalytic activities towards both OER and ORR with a low OER overpotential ( η OER @ 10 mA c m − 2 = 354 mV), good chemical reaction kinetics (Tafel slope = 94.21 mV dec−1 and 72.8 mV dec−1 for OER and ORR, respectively), and excellent durability (i.e., η OER @ 10 mA c m − 2 increases from 354 mV to 404 mV within 24 h; better durability than the commercial 30 wt.% Pt/C at 0.4 V vs RHE regarding ORR). It also presents the best bifunctional property among the reported perovskites. The excellent electrocatalytic properties of BiSCF can be attributed to its abundant oxygen vacancies and rich oxidation states of Co and Fe. With high activities, excellent stability and easy fabrication, BiSCF is expected to be a promising bifunctional oxygen electrocatalyst for renewable energy conversion and storage devices.

There is keen interest in using Ti alloys as lightweight structural materials for aerospace and automotive industries. However, a long-standing problem for these materials is their poor oxidation resistance. Herein, we designed and fabricated a Ti5Si3 reinforced Ti-4(wt.%)Mo composite with two-scale network architecture by low energy milling and spark plasma sintering. It displays superior oxidation resistance at 800°C owing to the in-situ formation of a multi-component surface layer. This oxide layer has a dense grain size gradient structure that consists of an outer TiO2 layer and an inner SiO2-padding-TiO2 layer, which has remarkable oxidation resistance and thermal stability. Furthermore, it was revealed that the hitherto unknown interaction between Ti5Si3 reinforcement and nitrogen during oxidation would contribute to the formation of a TiN nano-twin interface layer, which accommodates the thermal mismatch strain between the oxide layer and matrix. This, along with high adhesion, confers excellent thermal cycling life with no cracking or spallation during long-term oxidation. In this regard, the secure operating temperature of this new composite can be increased to 800°C, which provides a design pathway for a new family of Ti matrix composites for high-temperature applications.

CoCrFeNi high entropy alloy (HEA) has attracted extensive attention due to its excellent corrosion resistance, but the low strength limits its engineering application prospects. In order to develop CoCrFeNi based HEAs with high strength, ductility and corrosion resistance, the effects of Zr content on the microstructure, mechanical properties and corrosion resistance of heterogeneous CoCrFeNiZrx (x = 0, 0.25, 0.5 and 1) HEAs were investigated in this work. The results indicate that the increase of Zr content can significantly affect the phase stability of the alloy, and promote the formation of intermetallic compounds (Ni7Zr2 and/or Laves phase) and the transformation of solid solution from face-centered cubic (FCC) structure (x = 0, 0.25 and 0.5) to body-centered cubic (BCC) structure (x = 1). Reasonable control of the Zr content can endow the alloy excellent comprehensive properties. Especially, for CoCrFeNiZr0.25 alloy, composed of FCC matrix and a small amount of Ni7Zr2 phases, the yield strength (∼655 MPa) is increased by nearly four times higher than that of Zr-free alloy, and it also has good ductility (fracture stain > 50%). Meanwhile, the corrosion resistance of CoCrFeNiZr0.25 alloy is better than that of SS304. The EIS results show that the addition of Zr reduces the stability of the passive film on the alloy, which can be related to the content of the beneficial oxide in the passive film and the thickness of the passive film through XPS analysis. Moreover, the work functions of different phases in CoCrFeNiZrx alloys were obtained by first-principles calculations, which further confirmed the selective corrosion mechanism of the CoCrFeNiZrx alloy combining the experimental results.

A facile and mild route to synthesize C-coated SiC nanosheets (SiC/C NSs) via wet-chemical etching in hydrofluoric acid (HF) at 60 °C for 48 h using carbon aluminum silicate (Al4SiC4) as raw materials is reported for the first time. HF molecule leads to the breaking of C-Al bonds in Al4SiC4, which eventually results in the formation of two-dimensional SiC nanosheets. A carbon layer with a thickness of approximately 1.5 nm is formed on the surface of SiC nanosheets due to the excess carbon. The prepared SiC/C NSs possess a smooth and rectangular sheet with a mean 150 nm in width, 500 nm in length and 10 nm in thickness, respectively. The crystallographic characterization indicates that 3C-SiC and 2H-SiC coexist and the parallel plane relationship of 3C/2H-SiC heterojunction is (111)3C-SiC//(001)2H-SiC. Due to the formed 3C-SiC/2H-SiC heterojunction and graphitic carbon, the fabricated electrode based on SiC/C NSs exhibits prolonged cycling stability and high specific areal capacitance as a promising supercapacitor candidate. It remains 91.2% retention even after 20000 cycles and 734 μF/cm2 at a scan rate of 10 mV/s.

In this study, functionally graded foam made of Inconel 625 superalloy was successfully produced using the template replication method, with open-cell polyurethane foams as a precursor. The products have a similar pore morphology as the templates and adjacent layers were successfully sintered together by particle bonding. Sound absorption experiments on graded metallic foams reveal that the sound absorption at particular frequency ranges can be improved by various permutations of foam layers. For graded foam of two distinct pore sizes, a mathematical equation was proposed to predict the location of the intersection point of the sound absorption curves, thereby aiding in graded foam design. An increase in sound absorption coefficients by resonance-like effects can be introduced before the intersection points by placing the foam layer of smaller pore size nearer to the sound source. The sound absorption performances can be further customized when the thickness proportion of the pore sizes is changed and when the number of distinct pore sizes used is increased. The sound absorption performance at lower frequencies is generally boosted by resonance-like effects when the layer of foam with the largest pore size is placed furthest from the sound source. Given the same composition of foam with a fixed thickness proportion of pore sizes, one can introduce resonance-like effects to improve the sound absorption performance compared to other permutations while possibly satisfying weight requirements in practical applications. This study provides valuable insights and mathematical guidelines in the design and manufacturing of functionally graded metallic foam for specific applications.

Bacterial cellulose (BC) is one of the most versatile natural biopolymers with unique physical, chemical, and biological features. However, the lack of intrinsic antibacterial property of native BC limits its broad biomedical applications where such property is highly required to prevent contamination or infection caused by attached bacteria. In this work, we developed a simple and facile method to fabricate a dual-functional BC membrane by physical incorporation of gold nanorods (GNRs) followed by deposition of a phase-transitioned bovine serum albumin (PTB) film. Due to the broad-spectrum antifouling property of the PTB film, the resulting membrane could prevent the adhesion and accumulation of bacteria. A few bacteria that broke through the protection of the PTB film could be eradicated under short-term irradiation of a near-infrared laser due to the excellent photothermal property of incorporated GNRs. The whole fabrication was conducted in a simple and environmentally friendly manner, avoiding complicated processes and toxic organic solvents. Moreover, because all the components were biocompatible, the resulting membrane showed negligible cytotoxicity in vitro and good histocompatibility in vivo. This work thus provided a reliable way to endow BC with antibacterial property, being beneficial for diverse biomedical applications.

Mineral carbonation of construction and demolition waste is a viable alternative for the reduction of CO2 emissions from industry. Concrete and cement, together with ceramic blocks, are the primary sources of calcium for mineral carbonation in which CO2 is fixed in a stable and inert process. One type of concrete was selected from 5 for the carbonation tests. Crushed, separated into size fractions, moistened to 20% and tested at 10 bars of CO2 for 24 to 720 h. Destruction of portlandite and ettringite phases was determined. Calcite precipitated as carbonate phase. Maximum carbonation was reached after 72 h, fixing 6.5% of CO2.

Confined metal clusters as sub-nanometer reactors for electrocatalytic N2 reduction reaction (eNRR) have received increasing attention due to the unique metal-metal interaction and higher activity than single-atom catalysts. Herein, the inspiration of the superior capacitance and unique microenvironment with regular surface cavities of the porous boron nitride (p-BN) nanosheets, we systematically studied the catalytic activity for NRR of transition-metal single-clusters in the triplet form (V3, Fe3, Mo3 and W3) confined in the surface cavities of the p-BN sheets by spin-polarized density functional theory (DFT) calculations. After a two-step screening strategy, Mo3@p-BN was found to have high catalytic activity and selectivity with a rather low limiting potential (–0.34 V) for the NRR. The anchored Mo3 single-cluster can be stably embedded on the surface cavities of the substrate preventing the diffusion of the active Mo atoms. More importantly, the Mo atoms in the Mo3 single-cluster would act as “cache” to accelerate electron transfer between active metal centers and nitrogen-containing intermediates via the intimate Mo-Mo interactions. The cooperation of Mo atoms can also provide a large number of occupied and unoccupied d orbitals to make the "donation–backdonation" mechanism more effective. This work not only provides a quite promising electrocatalyst for NRR, but also brings new insights into the rational design of triple-atom NRR catalysts.

Inspired by the phenomenon of superhydrophobic plants and animals in nature, 1,3,5,7-tetranitro-1,3,5,7-tetrazocane (HMX)@copper stearate (CS) core-shell composites with similar properties was prepared. A rough shell layer on the surface of the HMX was observed by scanning electron microscopy (SEM), and a series of in-depth characterization confirmed the successful generation of CS and the core-shell structure of the samples. Differential scanning calorimeter (DSC) proves that the crystal transition temperature (204 °C) and high temperature decomposition exothermal temperature (284 °C) of HMX@CS is almost unchanged compared with pure HMX, which means HMX and CS have good compatibility. Then, the H50 of the samples also increased continuously (16.6 cm→33.7 cm) when the CS shell content increased from 1% to 5%, indicating that the CS shell has a certain buffering performance, and CS will absorb some heat and melt under the stimulation of impact due to its low melting point, which improved impact sensitivity of HMX effectively further. Moreover, HMX@CS has excellent hydrophobic and oleophilic performance, shows excellent wettability with lipid binder, and samples with appropriate CS shell content can continue to combustion stably after covering water. This waterproof and low sensitivity coating provides a new way for the development of multifunctional energetic materials.

Inspired by the relatively recognized performance of transition metal sulfides in the oxidation of hydrazine, the catalytic properties of FeS2 and Fe3S4 are compared via the density functional theory calculations. Due to the different coordination numbers of iron-sulfur, the free energies of the dehydrogenation steps on FeS2 are far less than those on Fe3S4, which led to the much better catalytic performance of FeS2. Accordingly, FeS2 microspheres are rationally proposed as a more efficient electrocatalyst for hydrazine oxidation, which is then prepared by a facile one-step hydrothermal strategy. Such FeS2 microspheres show great activity for hydrazine oxidation with an onset oxidation potential of 0.22 V vs. reversible hydrogen electrode, and a peak current density of 16 mA cm−2. Meanwhile, stability and high faradaic efficiency (3.5e−/N2H4) is obtained for hydrazine oxidation to N2.

Electrocatalytic reduction of Cr(VI) to less toxic Cr(III) is deemed as a promising technique. Conventional electrocatalytic reduction is always driven by a constant cathodic potential, which exhibits a repelling action to Cr(VI) oxyanions in wastewater and consequently suppresses reduction kinetics. In order to remarkably accelerate Cr(VI) electrocatalytic reduction, we applied a pulsed potential on an Fe2+-NiFe LDH/NF electrode synthesized by in situ growth of Fe2+-doped NiFe LDH nanosheets on Ni foam using a spontaneous redox reaction. Under anodic potential section, HCrO4– anions are adsorbed on the electrode surface and reduced to Cr(III) by Fe2+. Then, Cr(III) ions are desorbed from the electrode surface under coulombic force. The regeneration of Fe2+ and direct reduction of Cr(VI) are achieved under cathodic potential section. The pulsed potential can achieve complete elimination of Cr(VI) within 60 min at an initial concentration of 10 mg L−1, and the removal efficiency shows a 60% increase with respect to that under constant cathodic potential.