Anomalous{1012}tensile twinning and subsequent detwinning in a friction stir processed carbon fiber-reinforced Mg composite

1.Main text Owing to their low density and high specific strength,magnesium alloys and magnesium-based composites have great potential as structure metal materials in applications where lightweight matters[1–4].Deformation twins[5],especially the{1012}tension twins(also called tensile or extension twins)with a low critical resolved shear stress(CRSS)[6],are commonly observed in Mg alloys.They can provide the much-needed deformation along the c-axis in their hcp structure resulting from the very few easily activated slip systems in this crystal structure[7].The tensile twinning activation usually follows the macroscopic Schmid factor law[2],i.e.,the twin variant with the highest Schmid factor occurs,and it only appears when its Schmid factor is positive.

Preparation of single atom catalysts for high sensitive gas sensing

Single atom catalysts(SACs)have garnered significant attention in the field of catalysis over the past decade due to their exceptional atom utilization efficiency and distinct physical and chemical properties.For the semiconductor-based electrical gas sensor,the core is the catalysis process of target gas molecules on the sensitive materials.In this context,the SACs offer great potential for highly sensitive and selective gas sensing,however,only some of the bubbles come to the surface.To facilitate practical applications,we present a comprehensive review of the preparation strategies for SACs,with a focus on overcoming the challenges of aggregation and low loading.Extensive research efforts have been devoted to investigating the gas sensing mechanism,exploring sensitive materials,optimizing device structures,and refining signal post-processing techniques.Finally,the challenges and future perspectives on the SACs based gas sensing are presented.

Recent Advances in Nanoengineering of Electrode-Electrolyte Interfaces to Realize High-Performance Li-Ion Batteries

A suitable interface between the electrode and electrolyte is crucial in achieving highly stable electrochemical performance for Li-ion batteries,as facile ionic transport is required.Intriguing research and development have recently been conducted to form a stable interface between the electrode and electrolyte.Therefore,it is essential to investigate emerging knowledge and contextualize it.The nanoengineering of the electrode-electrolyte interface has been actively researched at the electrode/electrolyte and interphase levels.This review presents and summarizes some recent advances aimed at nanoengineering approaches to build a more stable electrode-electrolyte interface and assess the impact of each approach adopted.Furthermore,future perspectives on the feasibility and practicality of each approach will also be reviewed in detail.Finally,this review aids in projecting a more sustainable research pathway for a nanoengineered interphase design between electrode and electrolyte,which is pivotal for high-performance,thermally stable Li-ion batteries.

Polymer composite for antistatic application in aerospace

The pheno menon of static electricity is unpredictable,particulariy when an aircraft flying at high altitude that causes the accumulation of static charges beyond a threshold value leading to the failure of its parts and systems including severe explosion and radio communication failure.The accumulation of static charges on aircraft is generated by the virtue of interaction between the outer surface of aircraft and the external environmental attributes encompasses air particles,ice,hail,dust,volcanic ash in addition to its triboelectric charging.In the recent years,advanced polymer-based composites or nanocomposites are preferred structural constituents for aircrafts due to their light weight and comparable mechanical properties,but such composite systems do not render low impedance path for charge flow and are subsequently vulnerable to effect of lightning strike and precipitation static.In this context,it is essential to develop conductive composite systems from non-co nductive polymer natrix by nano fillerembodime nts.The advent of carbon-based nanocomposite/nano materials have adequately addressed such issues related to the nonco nductive polymer matrix and further turned into an avant-garde genre of materials.The current review envisioned to illustrate the detailed exploitation of various polymer nanocomposites in addition to especially mentioned epoxy composites based on carbon fillers like carbon black,carbon nanotube(single walled carbon nanotube and multi walled carbon nanotube) and graphene the development of antistatic application in aircra ft in addition to the static charge phenomenon and condition for its prevalence in avionic systems.

Ionic liquid/tetraglyme hybrid Mg[TFSI]_2 electrolytes for rechargeable Mg batteries

The electrochemical reversibility of Mg in hybrid electrolytes based on mixtures of ionic liquid and glyme based organic solvents was investigated for applications in rechargeable magnesium batteries(RMBs). The electrolytes demonstrate reversible reduction and oxidation of Mg only after being pre-treated with the dehydrating agent, magnesium borohydride, Mg[BH_4]_2, highlighting the importance of removing water in Mg based electrolytes. The addition magnesium di[bis(trifluoromethanesulfonyl)imide](Mg[TFSI]_2)(0.3 M) to N-butyl-n-methyl-pyrrolidinium bis(trifluoromethanesulfonyl)imide [C4 mpyr][TFSI]/tetraglyme at a mole ratio of 1:2 showed stable CV cycling over almost 300 cycles while scanning electron microscopy(SEM) and X-ray diffraction(XRD) confirmed Mg deposition, showing non-dendritic morphology and a well-aligned growth. Further thermogravimetric analysis(TGA) demonstrated a mass retention of 79% at 250℃ for this electrolyte suggesting that the presence of the ionic liquid increases thermal stability substantially making these hybrid electrolytes compatible for RMBs.

Microstructures, mechanical properties, corrosion, and biocompatibility of extruded Mg-Zr-Sr-Ho alloys for biodegradable implant applications

In this study,the microstructures,mechanical properties,corrosion behaviors,and biocompatibility of extruded magnesium-zirconiumstrontium-holmium(Mg-Zr-Sr-Ho)alloys were comprehensively investigated.The effect of different concentrations of Ho on the microstructural characteristics,tensile and compressive properties,corrosion resistance,and biocompatibility were investigated.The microstructures of the extruded Mg-1Zr-0.5Sr-xHo(x=0.5,1.5,and 4 wt.%)alloys consisted ofα-Mg matrix,fineα-Zr particles,and intermetallic phase particles of Mg_(17)Sr_(2) and Ho_(2)Mg mainly distributed at the grain boundaries.Extensive{1012}tensile twins were observed in the partially recrystallized samples of Mg-1Zr-0.5Sr-0.5Ho and Mg-1Zr-0.5Sr-1.5Ho.Further addition of Ho to 4 wt.%resulted in a complete recrystallization due to activation of the particle stimulated nucleation around the Mg_(17)Sr_(2) particles.The evolution of a rare earth(RE)texture was observed with the Ho addition,which resulted in the weakened basal and prismatic textures.Furthermore,a drastic increase of 200%in tensile elongation and 89%in compressive strain was observed with Ho addition increased from 0.5 to 4 wt%,respectively.The tension-compression yield asymmetry was significantly decreased from 0.62 for Mg-1Zr-0.5Sr-0.5Ho to 0.98 for Mg-1Zr-0.5Sr-4Ho due to the weakening of textures.Corrosion analysis of the extruded Mg-Zr-Sr-Ho alloys revealed the presence of pitting corrosion.A minimum corrosion rate of 4.98 mm y^(−1) was observed in Mg-1Zr-0.5Sr-0.5Ho alloy.The enhanced corrosion resistance is observed due to the presence of Ho_(2)O_(3) in the surface film which reduced galvanic effect.The formation of a stabilized surface film due to the Ho_(2)O_(3) was confirmed through the electrical impedance spectroscopy and XPS analysis.An in vitro cytotoxicity assessment revealed good biocompatibility and cell adhesion in relation to SaOS2 cells.

Meltblown fabric vs nanofiber membrane, which is better for fabricating personal protective equipments

The coronavirus disease 2019(COVID-19)pandemic has led to a great demand on the personal protection products such as reusable masks.As a key raw material for masks,meltblown fabrics play an important role in rejection of aerosols.However,the electrostatic dominated aerosol rejection mechanism of meltblown fabrics prevents the mask from maintaining the desired protective effect after the static charge degradation.Herein,novel reusable masks with high aerosols rejection efficiency were fabricated by the introduction of spider-web bionic nanofiber membrane(nano cobweb-biomimetic membrane).The reuse stability of meltblown and nanofiber membrane mask was separately evaluated by infiltrating water,75%alcohol solution,and exposing under ultraviolet(UV)light.After the water immersion test,the filtration efficiency of meltblown mask was decreased to about 79%,while the nanofiber membrane was maintained at 99%.The same phenomenon could be observed after the 75%alcohol treatment,a high filtration efficiency of 99%was maintained in nanofiber membrane,but obvious negative effect was observed in meltblown mask,which decreased to about 50%.In addition,after long-term expose under UV light,no filtration efficiency decrease was observed in nanofiber membrane,which provide a suitable way to disinfect the potential carried virus.This work successfully achieved the daily disinfection and reuse of masks,which effectively alleviate the shortage of masks during this special period.

A Thermoregulatory Flexible Phase Change Nonwoven for All‑Season High‑Efficiency Wearable Thermal Management

Phase change materials have a key role for wearable thermal management,but suffer from poor water vapor permeability,low enthalpy value and weak shape stability caused by liquid phase leakage and intrinsic rigidity of solid–liquid phase change materials.Herein,we report for the first time a versatile strategy for designed assembly of high-enthalpy flexible phase change nonwovens(GB-PCN)by wet-spinning hybrid grapheneboron nitride(GB)fiber and subsequent impregnating paraffins(e.g.,eicosane,octadecane).As a result,our GB-PCN exhibited an unprecedented enthalpy value of 206.0 J g^(−1),excellent thermal reliability and anti-leakage capacity,superb thermal cycling ability of 97.6%after 1000 cycles,and ultrahigh water vapor permeability(close to the cotton),outperforming the reported PCM films and fibers to date.Notably,the wearable thermal management systems based on GB-PCN for both clothing and face mask were demonstrated,which can maintain the human body at a comfortable temperature range for a significantly long time.Therefore,our results demonstrate huge potential of GB-PCN for human-wearable passive thermal management in real scenarios.

X-ray analysis of twin dominated deformation in an aged Mg-7Sn-3Zn-0.04Na alloy

In-situ transmission X-ray diffraction based compression deformation experiments are performed to study the twinning behaviour in asextruded(non-aged)and peak-aged Mg-7Sn-3Zn-0.04Na alloy.The axial lattice strains were measured in the parent grains,twins and the precipitates as a function of applied stress.The critical shear stress for achieving 5%twinning was found to be increased by∼26MPa by the presence of 7%of Sn and by∼50MPa by the presence of the particles formed after 10 h of aging.The evolution of twin volume fraction with plastic strain is similar in both non-aged and aged conditions,indicating no change in the relative activities of slip and twin in the ideally oriented(10.10)parent grains.Predictions made in previous studies of twin thickening stresses and twin bypass stresses agree reasonably well with the measured values,given the experimental error.Considerable relaxation was seen in the precipitate lattice reflections.This is attributed to relaxation effects continuing during X-ray data collection.Macroscopic flow curves confirm that precipitate hardening in the present system is particularly sensitive to relaxation effects.This is likely to be an important consideration for fatigue loading of precipitate hardened samples.

Two-dimensional Boron Nitride for Electronics and Energy Applications

Two-dimensional(2D)boron nitride(BN),the so-called“white graphene,”has demonstrated a great potential in various fields,particularly in electronics and energy,by utilizing its wide bandgap(~5.5 eV),superior thermal stability,high thermal conductance,chemical inertness,and outstanding dielectric properties.However,to further optimize the performances from the view of structure-property relationship,the determinative factors such as crystallite sizes,layer thickness,dispersibility,and surface functionalities should be precisely controlled and adjusted.Therefore,in this review,the synthesis and functionalization methods including“top-down”and“bottom-up”strategies,and non-covalent and covalent modifications for 2D BN are systematically classified and discussed at first,thus catering for the requirements of versatile applications.Then,the progresses of 2D BN applied in the fields of microelectronics such as fieldeffect transistors and dielectric capacitors,energy domains such as thermal energy management and conversion,and batteries and supercapacitors are summarized to highlight the importance of 2D BN.Notably,these contents not only contain the state-of-the-art 2D BN composites,but also bring the current novel design of 2D BN-based microelectronic units.Finally,the challenges and perspectives are proposed to better broaden the scope of this material.Therefore,this review will pave an all-around way for understanding,utilizing,and applying 2D BN in future electronics and energy applications.

A Thermochromic, Viscoelastic Nacre-like Nanocomposite for the Smart Thermal Management of Planar Electronics

Cutting-edge heat spreaders for soft and planar electronics require not only high thermal conductivity and a certain degree of flexibility but also remarkable self-adhesion without thermal interface materials, elasticity, arbitrary elongation along with soft devices, and smart properties involving thermal self-healing, thermochromism and so on. Nacre-like composites with excellent in-plane heat dissipation are ideal as heat spreaders for thin and planar electronics. However, the intrinsically poor viscoelasticity, i.e., adhesion and elasticity, prevents them from simultaneous self-adhesion and arbitrary elongation along with current flexible devices as well as incurring high interfacial thermal impedance. In this paper, we propose a soft thermochromic composite(STC) membrane with a layered structure, considerable stretchability, high in-plane thermal conductivity(~30 Wm^(-1) K^(-1)), low thermal contact resistance(~12 mm^2 KW^(-1), 4–5 times lower than that of silver paste), strong yet sustainable adhesion forces(~4607 Jm^(-2), 2220 Jm^(-2) greater than that of epoxy paste) and self-healing efficiency. As a self-adhesive heat spreader, it implements efficient cooling of various soft electronics with a temperature drop of 20℃ than the polyimide case. In addition to its self-healing function, the chameleon-like behavior of STC facilitates temperature monitoring by the naked eye, hence enabling smart thermal management.

Effect of plastic deformation on microstructure and thermoelectric properties of Mg_(2)Sn alloys

In the present work,the effect of deformation on microstructure and thermoelectric properties of Mg 2 Sn alloys having excess magnesium concentrations is examined.The cast alloys were prepared using radio-frequency(RF)induction melting under an argon atmosphere.These alloys were thermo-mechanically processed via compression at different temperatures to various true strains.At room temperature,the alloys failed at a true strain of∼13%.However,at elevated temperatures,the alloys were observed to be highly plastic.For alloys compressed at 673 K to a true strain of 1,a prominent substructure formed.The subgrain size was∼3-5μm.It is believed that the substructure arose from the action of dynamic recovery.Following deformation,the thermoelectric performance of alloy prepared with 6.7 wt.%excess Mg was improved compared to the as cast condition.This can be ascribed to a reduction in the thermal conductivity due to phonon scattering at grain boundaries.

MOF-Like 3D Graphene-Based Catalytic Membrane Fabricated by One-Step Laser Scribing for Robust Water Purification and Green Energy Production

Increasing both clean water and green energy demands for survival and development are the grand challenges of our age.Here,we successfully fabricate a novel multifunctional 3D graphene-based catalytic membrane(3D-GCM)with active metal nanoparticles(AMNs)loading for simultaneously obtaining the water purification and clean energy generation,via a“green”one-step laser scribing technology.The as-prepared 3D-GCM shows high porosity and uniform distribution with AMNs,which exhibits high permeated fluxes(over 100 L m^(−2) h^(−1))and versatile super-adsorption capacities for the removal of tricky organic pollutants from wastewater under ultra-low pressure-driving(0.1 bar).After adsorption saturating,the AMNs in 3D-GCM actuates the advanced oxidization process to self-clean the fouled membrane via the catalysis,and restores the adsorption capacity well for the next time membrane separation.Most importantly,the 3D-GCM with the welding of laser scribing overcomes the lateral shear force damaging during the long-term separation.Moreover,the 3D-GCM could emit plentiful of hot electrons from AMNs under light irradiation,realizing the membrane catalytic hydrolysis reactions for hydrogen energy generation.This“green”precision manufacturing with laser scribing technology provides a feasible technology to fabricate high-efficient and robust 3D-GCM microreactor in the tricky wastewater purification and sustainable clean energy production as well.

Ultrathin origami accordion-like structure of vacancy-rich graphitized carbon nitride for enhancing CO_(2) photoreduction

Retaining the ultrathin structure of two-dimensional materials is very important for stabilizing their catalytic performances.However,aggregation and restacking are unavoidable,to some extent,due to the van der Waals interlayer interaction of two-dimensional materials.Here,we address this challenge by preparing an origami accordion structure of ultrathin twodimensional graphitized carbon nitride(oa-C_(3)N_(4))with rich vacancies.This novel structured oa-C_(3)N_(4) shows exceptional photocatalytic activity for the CO_(2) reduction reaction,which is 8.1 times that of the pristine C_(3)N_(4).The unique structure not only prevents restacking but also increases light harvesting and the density of vacancy defects,which leads to modification of the electronic structure,regulation of the CO_(2) adsorption energy,and a decrease in the energy barrier of the carbon dioxide to carboxylic acid intermediate reaction.This study provides a new avenue for the development of stable highperformance two-dimensional catalytic materials.

Latest progresses and the application of various electrolytes in high-performance solid-state lithium-sulfur batteries

With the emergence of some solid electrolytes(SSEs)with high ionic conductivity being comparable to liquid electrolytes,solid-state lithium-sulfur batteries(SSLSBs)have been widely regarded as one of the most promising candidates for the next generation of power generation energy storage batteries,and have been extensively researched.Though many fundamental and technological issues still need to be resolved to develop commercially viable technologies,SSLSBs using SSEs are expected to address the present limitations and achieve high energy and power density while improving safety,which is very attractive to large-scale energy storage systems.SSLSBs have been developed for many years.However,there are few systematic discussions related to the working mechanism of action of various electrolytes in SSLSBs and the defects and the corresponding solutions of various electrolytes.To fill this gap,it is very meaningful to review the recent progress of SSEs in SSLSBs.In this review,we comprehensively investigate and summarize the application of SSEs in LSBs to determine the differences which still exist between current progresses and real-world requirements,and comprehensively describe the mechanism of action of SSLSBs,including lithium-ion transport,interfacial contact,and catalytic conversion mechanisms.More importantly,the selection of solid electrolyte materials and the novel design of structures are reviewed and the properties of various SSEs are elucidated.Finally,the prospects and possible future research directions of SSLSBs including designing high electronic/ionic conductivity for cathodes,optimizing electrolytes and developing novel electrolytes with excellent properties,improving electrode/-electrolyte interface stability and enhancing interfacial dynamics between electrolyte and anode,using more advanced test equipment and characterization techniques to analyze conduction mechanism of Li^(+)in SSEs are presented.It is hoped that this review can arouse people’s attention and enlighten the development of functional materials and novel structures of SSEs in the next step.

A rational design of bimetallic PdAu nanoflowers as efficient catalysts for methanol oxidation reaction

Methanol fuel cells have been intensively developed as clean and high-efficiency energy conversion system due to their high efficiency and low emission of pollutants.Here,we developed a simple aqueous synthetic method to prepare bimetallic PdAu nanoflowers catalysts for methanol oxidation reaction(MOR)in alkaline environment.Their composition can be directly tuned by changing the ratio between Pd and Au precursors.Compared with commercial Pd/C catalyst,all of the PdAu nanoflowers catalysts show the enhanced catalytic activity and durability.In particular,the PdAu nanoflowers specific activity reached 0.72 mA/cm^(2),which is 14 times that of commercial Pd/C catalyst.The superior MOR activity could be attributed to the unique porous structure and the shift of the d-band center of Pd.

蚕丝基生物材料精准和功能性组装的3D打印策略

In recent years,significant progress has been made in both three-dimensional(3D)printing technologies and the exploration of silk as an ink to produce biocompatible constructs.Combined with the unlimited design potential of 3D printing,silk can be processed into a broad range of functional materials and devices for various biomedical applications.The ability of silk to be processed into various materials,including solutions,hydrogels,particles,microspheres,and fibers,makes it an excellent candidate for adaptation to different 3D printing techniques.This review presents a didactic overview of the 3D printing of silk-based materials,major categories of printing techniques,and their prototyping mechanisms and structural features.In addition,we provide a roadmap for researchers aiming to incorporate silk printing into their own work by summarizing promising strategies from both technical and material aspects,to relate state-of-the-art silk-based material processing with fast-developing 3D printing technologies.Thus,our focus is on elucidating the techniques and strategies that advance the development of precise assembly strategies for silk-based materials.Precise printing(including high printing resolution,complex structure realization,and printing fidelity)is a prerequisite for the digital design capability of 3D printing technology and would definitely broaden the application era of silk,such as complex biomimetic tissue structures,vasculatures,and transdermal microneedles.

Comprehensive insights into recent innovations:Magnesium-inclusive high-entropy alloys

This review focuses on thermodynamic and physical parameters,synthesis methods,and reported phases of Magnesium(Mg)containing high-entropy alloys(HEAs).Statistical data of publications concerning Mg-containing HEAs were collected and analyzed.Data on the chemical elements included in Mg-containing HEAs,their theoretical end experimental densities,thermodynamic parameters,physical parameters,fabricated techniques and reported phases were also collected and discussed.On the basis of this information,a new classification for HEAs was proposed.It is also shown that the existing thermodynamic parameters cannot accurately predict the formation of a single phase solid solution for Mg-containing HEAs.The physical parameters of Mg-containing HEAs are within a wide range,and most of the synthesized Mg-containing HEAs have a complex multiphase structure.

多孔碳负载五氧化二铌及其在超级电容器中的应用

以间苯二酚、甲醛和草酸铌为原料,通过原位聚合和高温煅烧,制备出多孔碳负载的五氧化二铌（Nb2O5）材料。X射线粉末衍射和扫描电镜分析表明,负载在多孔碳表面上的五氧化二铌具有三维纳米凸起结构,属于正交晶型。循环伏安测试表明该复合材料的比电容达到290 F·g-1,并具有良好的大电流放电能力,5 A·g-1的放电电流下,容量可以达到108 F·g-1。0.5 A·g-1的首次放电容量为355 F·g-1（1.0~3.0 V vs.Li＋/Li）,100次循环后容量保持率为82%。通过对交流阻抗图谱和等效电路的模拟分析,对其电化学赝电容特性进行了讨论。该复合材料降低了电解液中离子在充放电过程中的迁移路径和扩散阻力,实现Nb2O5活性材料的多维度接触,提高了Nb2O5的导电性,改善了其超级电容特性。

Enhanced ductility and reduced asymmetry of Mg-2Al-1Zn alloy plate processed by torsion and annealing

The ductility and plastic asymmetry of an as-annealed magnesium alloy plate were studied in compression through combined process of torsion and subsequent annealing by optical microscope and EBSD. The yield strength（YS） and ultimate compression strength（UCS） as well as the compression ductility（CD） were simultaneously raised by prior torsion at room temperature. The CD was further enhanced by subsequent annealing. Also, the torqued sample followed by annealing experienced a rising CD with the increase in prior strain, leading to the maximum true strain of 0.279, which is twice that of the as-annealed original one. The sample showed a largely reduced tension-compression yield asymmetry by subjecting to pre-torsion alone or combined with a subsequent annealing. The enhanced ductility and reduced asymmetry are attributed to the development of a gradient microstructure with refined grains, and also randomization of the weakened texture due to torsion and subsequent annealing.