查看更多>>摘要：Electrochemical water splitting,as an effective sustainable and eco-friendly energy conversion strategy,can produce high-purity hydrogen(H2)and oxygen(O2)via hydrogen evolution reaction(HER)and oxy-gen evolution reaction(OER),respectively,altering the nonrenewable fossil fuels.Here,La0.6Sr0.4CoO3 per-ovskite oxide nanoparticles with an orthorhombic phase were synthesized within 2 min in a one-step reaction,using a rapid and efficient high-temperature shock(HTS)method.Impressively,the as-prepared La0.6Sr0.4CoO3 with orthorhombic phase(HTS-2)exhibited better OER and HER performance than the hexagonal phase counterpart prepared using the traditional muffle furnace calcination method.The elec-trocatalytic performance enhancement of orthorhombic La0.6Sr0.4CoO3 can be attributed to the novel or-thorhombic structure,such as confined strontium segregation,a higher percentage of highly oxidative oxygen species,and more active sites on the surface.This facile and rapid synthesis technique shows great potential for the rational design and crystal phase engineering of nanocatalysts.
Rajesh RajagopalYuvaraj SubramanianYu Jin JungSung Kang...
8-16页
查看更多>>摘要：Li2S-P2S5-type inorganic solid electrolytes with cation and/or anion doping are considered to be promis-ing candidates for all-solid-state batteries(ASSBs),due to their high ionic conductivity and electrochem-ical performances.However,compositional tuning of Li2S-P2S5 type inorganic solid electrolytes without doping has not been fully studied.In this work,Li-rich Li7P2S8I solid electrolyte was prepared with com-positional tuning by high energy ball mill process.The crystalline nature and the structural character-istics of the prepared solid electrolytes were studied with several physiochemical techniques.The effect of compositional tuning and the associated limitations were analyzed by laser Raman spectroscopy and solid-nuclear magnetic resonance spectroscopy(NMR)analysis techniques.The prepared Li-rich Li7P2S8I solid electrolyte exhibited higher ionic conductivity(6.27 mS cm-1)than the bare Li7P2S8I solid elec-trolyte(5.16 mS cm-1).Further,the prepared Li7.1P2S8.1I0.9 solid electrolyte is highly stable against lithium metal anode and is stable up to 600 charge-discharge cycles.Thus,the fabricated ASSB using Li-rich Li7P2S8I solid electrolyte exhibited excellent cycle stability of 97％specific capacity retention with less interfacial reaction.Electrochemical impedance spectroscopy and the laser Raman spectroscopy analy-sis after galvanostatic charge-discharge cycling confirmed the electrochemical stability of Li-rich Li7P2S8l solid electrolyte.
查看更多>>摘要：Nano-structured silicon(Si)has demonstrated high capacity for lithium storage;however,it suffers from unsatisfactory cycling stability caused by large volume change and poor interface stability.Thus,it is very important to construct functional coatings on nano-structured Si to buffer the volume change and im-prove the interface stability.Herein,we successfully construct V2O3 and carbon(C)dual-layer coatings on Si nanoparticles with ultrathin and uniform thickness using a facile spray drying and chemical vapour deposition method.The as-prepared Si@V2O3@C manifests a high specific capacity of 2230 mAh g-1 af-ter 100 cycles under the current density of 200 mA g-1,showing its promising application prospect in lithium storage.In situ electrochemical impedance spectroscopy(EIS)results at different lithiation states and different cycles show a more stable interface resistance of Si@V2O3@C than pristine Si.The V2O3 and C dual coating layers not only ensure the Si nanoparticles with high structural stability by buffering vol-ume expansion and preventing electrolyte penetration,but also guarantee a superior electron transport rate because of the metallic V2O3 as well as the highly conductive carbon layers.
查看更多>>摘要：MXene-based composite films are regarded as up-and-coming multifunctional electromagnetic interfer-ence(EMI)shielding materials.However,the conflict between strong mechanical properties and high electrical conductivity hinders their application in modern integrated electronics.Herein,in virtue of density-induced sedimentation,robust and multifunctional liquid metals-reinforced cellulose nanofibers(CNF)/MXene(LMs-CNF/MXene)composite films with Janus structure are fabricated by one-step vacuum-assisted filtration method.Not only does the nacre-like structure of the CNF/MXene layer not destroy,but the deposited liquid metals(LMs)layer can serve as conductive potentiation.Due to the special Janus structure,an"absorption-reflection-reabsorption"shielding process is created in LMs-CNF/MXene composite film to strengthen EMI shielding performance.Its shielding effectiveness can reach 51.9 dB at～27 μm,and the reflection coefficient falls to 0.89,below those of reported MXene-based shielding films.Meanwhile,the CNF/MXene layer can endow composite films with excellent mechanical properties with a super tensile strength of 110.3 MPa.Notably,the LMs-CNF/MXene EMI shielding composite films also integrate outstanding photo-/electrothermal conversion performances,which can effectively deice out-doors.The robust LMs-CNF/MXene EMI shielding composite films with satisfying photo-/electrothermal performances have extensive application prospects,such as aerospace,wearable electronics,and portable electronics.
查看更多>>摘要：Selective laser melting(SLM)and directed energy deposition(DED),as two important additive manufac-turing(AM)methods,have garnered widespread industrial applications attributing to their advantages in fabricating complex structures.Since the complex nature of microstructures produced by different AM technologies,it is necessary to carry out a thorough investigation of the stress corrosion cracking(SCC)behavior affected by these microstructures in harsh environments(i.e.hydrofluoric acid(HF)).In this study,the SCC susceptibility of DED and SLM-fabricated 316 L in HF vapor was first systematically studied by comparing it with commercial wrought(WR)316 L to reveal the effect of microstructures(columnar crystals,melt pools,δ-ferrites,and dislocation cells)on the SCC behavior.Results show that DED-316 L has excellent SCC resistance and such resistance exhibits a low correlation with loading direction.This is because the reticulated distributed skeletal δ-ferrite facilitates enhancing film protection and hindering dislocation slip transfer.In contrast,SLM-316 L exhibits high SCC sensitivity together with a strong load-ing direction correlation.An SLM-316L-V with melt pool boundaries oriented perpendicular to the stress exhibits a high SCC tendency.Moreover,the dislocation cells without elemental segregation in SLM-316 L activate the corrosion reactivity and favor dislocation proliferation and transport,making SCC deterio-ration of SLM-316L-V in HF vapor.While a proper loading relationship can shield the adverse effect of dislocation cells on the stress corrosion of SLM-316 L(e.g.SLM-316L-H).Our efforts provide important theoretical guidance for the rational selection of fabrication technologies and microstructural design of materials in harsh environments.
查看更多>>摘要：Hydrogen storage plays a pivotal role in the hydrogen industry,yet its current status presents a bottle-neck.Diverse strategies have emerged in recent years to address this challenge.MgH2 has stood out as a promising solid-state hydrogen storage material due to its impressive gravimetric and volumetric hy-drogen density,but its practical application is hampered by elevated thermal stability and sluggish kinet-ics.In this study,we introduce a solution by synthesizing Pd metallene through a one-pot solvothermal method,revealing a distinctive highly curved lamellar structure with a thickness of around 1.6 nm.Incor-porating this Pd metallene into MgH2 results in a composite system wherein the starting dehydrogenation temperature is significantly lowered to 439 K and complete dehydrogenation occurs at 583 K,releasing 6.14 wt.％hydrogen.The activation energy of dehydrogenation for MgH2 was reduced from 170.4 kJ mol-1 to 79.85 kJ mol-1 after Pd metallene decoration.The enthalpy of dehydrogenation of the MgH2-10 wt.％Pd sample was calculated to be 73 kJ mol-1 H2-1 and decreased by 4.4 kJ mol-1 H2-1 from that of dehy-drogenation of pure MgH2(77.4 kJ mol-1 H2-1).Theoretical calculations show that the average formation energy and average adsorption energy of hydrogen vacancies can be significantly reduced in the presence of both Pd clusters and Pd single atoms on the surface of MgH2/Mg,respectively.It suggests that the synergistic effect of in situ formed Pd single atoms and clusters significantly improves the hydrogenation and dehydrogenation kinetics.The identified active sites in this study hold potential as references for forthcoming multi-sized active site catalysts,underscoring a significant advancement toward resolving hydrogen storage limitations.
查看更多>>摘要：In this study,a high-ductility AZ91 magnesium alloy was fabricated by the novel continuous rheo-squeeze casting-extrusion(CRSCE)process.The semi-solid slurry was prepared by ultrasonic vibration(UV)treat-ment,then solidified under pressure,and finally hot extruded.UV treatment can reduce the Al element content in primary grains and increase it in secondary grains.The refined Mg17Al12 phase was scattered along secondary grain boundaries and then stretched into narrow,fibrous bands during the hot extrusion.The fibrous bands with proper separation distances can accelerate the dynamic recrystallization(DRX)process and suppress the growth of DRXed grains.Microcracks were initiated inside the brittle Mg17Al12 phase and tended to propagate along the continuously distributed Mg17Al12 phase during the tensile test.Thus,the tiny Mg17Al12 phase in the billet and narrow,fibrous bands in as-extruded rods can prevent cracks from spreading and enhance ductility.Therefore,excellent comprehensive mechanical properties were obtained,with an ultimate tensile strength of 326.3 MPa and an elongation of 16.46％.The CRSCE method offers a novel way to fabricate high-ductility and high-alloyed magnesium alloys without ho-mogenization.Microstructure regulation mechanisms of CRSCE,microstructural hereditary laws,and the effect of the Mg17Al12 phase on mechanical properties were further discussed.
查看更多>>摘要：Photo-assisted rechargeable energy storage devices are a promising strategy to achieve sustainable de-velopment by simultaneously integrating solar energy conversion and supercapacitor storage.Herein,we fabricated a light-sensitive macroporous film based on carbon nanotube(CNT),intercalated with Co2V2O7,and then modified by black phosphorus quantum dots(BPQD).Physico-chemical characterization and density functional theory are employed to investigate the improved photo-assisted charge storage capa-bility and the underlying mechanism.It is demonstrated that photo-generated carriers can be separated efficiently,and the formed abundant interfaces could modulate the electronic structure of the electrode,effectively improving the conductivity.Under visible light,the electrode displays an ultra-high capacity of 138.4 mA h g-1(197.9 mA h cm-3)at 1 A g-1.Besides,the CNT@Co2V2O7/BPQD supercapacitor shows a maximum energy density of 44.4 Wh kg-1(60.0 Wh L-1)at a power density of 800 W kg-1(960 W L-1)and excellent cyclic stability of 104.8％after 13,000 charge/discharge cycles.The above improvements are attributed to the reactivity and kinetics of electrochemically active components.This study reveals the synergistic effects of multi-interface on"light,photo-generated charge,and energy storage"and provides new possibilities in the controllable design of novel photo-assisted energy storage devices.
查看更多>>摘要：The strength-ductility inversion relationship of alloys is a persistent challenge in advanced materials de-sign.Al-Cu series cast aluminum alloys that are considered as an exceptionally high-strength light alloy are not exclusive in structural applications due to their inherently poor plasticity.In this work,we em-ployed a squeeze casting technique and Ca microalloying strategy for microstructure modulation to ef-fectively address this difficulty.The addition of low concentrations of Ca(0.5 wt.％and 1 wt.％)elements to the as-cast Al-5Cu-0.5Mn alloy significantly enhances its plasticity by threefold at room temperature.Unexpectedly,even after T6 treatment,which typically compromises ductility for increased strength,the low-Ca micro-alloyed Al-5Cu-0.5Mn exhibited a further increase in its strength without sacrificing its ductility.The low-Ca addition to the alloy generates an ultrafine eutectic colony with a complex"core-shell"structure,which can serve as a carrier for localized stress transfer,effectively distributing the strain uniformly to more grains.Precipitation hardening of α-Al grains and spheroidization of lamellar ultrafine eutectic phases were simultaneously realized in the low-Ca alloy after T6 heat treatment,which resulted in comparable hardness of α-Al grains and eutectic colonies.The synergistic coordination of external strains through extensive strain-hardening induced by slip line and substantial microcrack generation by ultrafine eutectic colonies is evidenced by a series of in situ characterizations of the low-Ca alloys.There-fore,the uniform spreading deformation due to the transfer of strain-hardening effect and the alternating plastic deformation of α-Al grains and ultrafine eutectic colonies are the critical keys to overcoming the strength-plasticity paradox in low-Ca alloys.This study provides a perspective route for Al-Cu system cast aluminum alloys to be utilized as high-strength and tough structural materials.
查看更多>>摘要：The chemical boundaries inside the ultrafine spinodal decomposition structure in metastable β-Ti al-loys can act as a new feature to architect heterogeneous microstructures.In this work,we combined two semi-empirical methods,i.e.,the d-electron theory and the e/a electron concentration,to achieve the spinodal decomposition structure in a metastable β Ti-4.5Al-4.5Mo-7V-1.5Cr-1.5Zr(wt.％)alloy.Utiliz-ing the spinodal decomposition structure,the aged Ti-Al-Mo-V-Cr-Zr alloys showed multi-architecturedα precipitates spanning from micron-scale(primary αp)to nano-scale(secondary αs)that were uni-formly distributed in the β-domains.Being compared with the forged sample,the multi-scale heteroge-neous microstructure enables the aged β-Ti alloy to have ultra-high strength(yield strength～1366 MPa and ultimate tensile strength～1424 MPa)and an appreciable ductility(～9.3％).Strengthening models were proposed for the present alloys to estimate the contribution of various microstructural features to the measured yield strength.While the solid solution strengthening,β-spinodal strengthening,and back stress strengthening made comparable contributions to the strength of the forged alloy,the back stress strengthening was the predominant strengthening effect in the aged alloy.This alloy design ap-proach based on chemical boundary engineering to construct multi-architectured α precipitates provided an effective strategy for achieving an outstanding combination of ultra-high strength and ductility in metastable β-Ti alloys.
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