查看更多>>摘要：CulnS2 quantum-dot(CIS QD)-modified g-C3N4(CN)catalysts(CIS/CN)were prepared with the aid of an in-situ growth process.The as-obtained photocatalysts were explored by measuring their crystallinity,surface morphology,binding energy and light absorption activity.The photocatalytic efficiency of the pho-tocatalysts was evaluated through photocatalytic water splitting for hydrogen production and tetracycline(TC)antibiotic degradation under the simulated solar light and visible light respectively.The optimized sample(10CIS/CN)showed the best photocatalytic activity:producing 102.4 μmol g-1 h-1 of hydrogen in 1 h,or degrading 52.16％of TC in 120 min,which were respectively 48 or 3.4 times higher than the photocatalytic activity of CN itself.The enhancement in the efficiency of the composite system was prin-cipally accredited to the enlargement of light absorption,the more effective in charge transfer and the dropping of the charge carrier pair recombination through a formed S-scheme heterojunctional interface.This work is an effort to adjust CN-based polysulfide QD for speedy photocatalysis.The enriched photo-catalytic activity grants a new sense for adjusting the optical properties of CN.
查看更多>>摘要：The effects of Co and Fe co-doping Ni-Mn-In alloy on the phase stability,lattice parameters,mag-netic properties,and electronic structures are systematically investigated by using the first-principles calculations.Results indicate that Fe atoms replace the excess Mn2 atoms by direct and indirect coex-istence(Fe→Mn2 and Fe→In→Mn2);Co substitutes the Ni atoms by direct substitution(Co→Ni)for the Ni-Mn-In alloy.The austenites all exhibit the ferromagnetic(FM)state for the studied composi-tions.The NM martensites are in the ferrimagnetic(FIM-1)state for the Ni2Mn1.5In0.5,Ni2Mn1.25In0.5Fe0.25,Ni1.75Mn1.5In0.5Co0.25,and Ni1.75Mn1.25In0.5Co0.25Fe0.25 alloys,while the other compositions are in the FM state.The phase stability of austenite and martensite decreases with increasing Co and Fe co-doping.A magnetic-structural coupling transition occurs at x＜0.25 and y＜0.25.The Ni1.91Mn1.5In0.5Co0.08 and Ni1.91Mn1.42In0.5Co0.08Fe0.08 alloys exhibit an A→6M→NM transformation,accompanied by a magnetic transition.When Co and Fe are co-doped,the hybridization strength between Co and Fe is greater than that between Co/Fe and Mn.The enhancement of magnetocaloric and elastocaloric effects is favored by larger magnetization difference(ΔM)and lattice volume change(ΔV/V0).Based on the calculated phase stability,magneto-structure coupling,ΔV/V0 and c/a ratio,one can predict that the Ni2-xMn1.5-yIn0.5CoxFey alloy with Co content 0 ≤ x ≤ 0.25 and Fe content 0 ≤ y ≤ 0.05 is predicted to have good magneto-controlled functional behavior.
查看更多>>摘要：The aim of this research was to elucidate the underlying mechanism involved in the formation of rare earth(RE)texture and pseudo fiber bimodal microstructure in the high ductility Mg-2Gd-0.4Zr alloy.The microstructure and texture evolution during the extrusion process were analyzed using various tech-niques,including optical microscopy(OM),scanning electron microscopy(SEM),electron backscatter diffraction(EBSD),and electron probe microanalysis(EPMA).The findings revealed that the RE texture in the extruded Mg-2Gd-0.4Zr alloy emerged during the dynamic recrystallization(DRX)process and was further strengthened during the subsequent static recrystallization and grain growth processes.The nu-cleation and growth of grains in the streamline region of Zr particles were delayed in comparison to other regions due to the pinning effect of Zr particles,ultimately resulting in the formation of pseudofiber bi-modal microstructure in the extruded Mg-2Gd-0.4Zr alloy.
查看更多>>摘要：Sodium-ion batteries are promising candidates for large-scale grid storage systems and other applica-tions.Their foremost advantage derives from superior environmental credentials,enhanced safety as well as lower raw material costs than lithium-ion batteries.It is still challenging to explore desirable anode material.In this study,FeSe2@CoSe2/FeSe2,with a yolk-shell structure was prepared by ion exchange and selenisation.The FeSe2@CoSe2/FeSe2 prepared as anode material for sodium-ion batteries exhibits excel-lent rate capability due to the synergistic effect of bimetallic selenides and the interfacial effect of the heterostructure.Moreover,it delivers high performance(510 mAh g-1 at 0.2 A g-1),superior rate capa-bility(90％retention at 5 A g-1),and good long-time cycling stability(78％capacity retention after 1800 cycles at a high current density of 2 A g-1).The optimized sodium-ion full cell with FeSe2@CoSe2/FeSe2 as the anode and Na3V2(PO4)3 as the cathode still demonstrates excellent performance.Namely,a ca-pacity of 272 mAh g-1(at 1 A g-1)within the operating voltage from 1 to 3.8 V can be obtained.This work illustrates the potential of bimetallic selenides with heterostructures for performance enhancement of sodium-ion batteries.
查看更多>>摘要：Yarn-based flexible strain sensors with advantages in wearability and integrability have attracted wide at-tention.However,it is still a big challenge to achieve yarn-based strain sensors with a wide linear strain range,low hysteresis,and durability synchronously that can be used for full range detection of human body motions.Herein,a new structure,double-threaded conductive yarn with rhythmic strain distribu-tion,is reported to markedly widen the linear strain range of microcrack-based stretchable strain sensors.A new method of winding and thermally adhering hot-melt filaments on the surface of the elastic fiber is used to achieve double-threaded yarn(DTY)with rhythmic strain distribution.The proposed strategy,the integration of heterogeneous materials,is reported to significantly reduce the mechanical hysteresis of composite yarns.Rhythmic strain distribution of the DTY during stretching causes multi-level micro-cracks in different regions of the carbon nanotube(CNT)conductive layer deposited on the surface of the DTY.Besides,the sensing performance of DTY-based strain sensor can be adjusted by designing the structural parameters.The final prepared flexible strain sensor has the advantages of a wide linear strain range(100％),great sensitivity(GF=12.43),low hysteresis,rapid response(158 ms),high repeatability(＞2000 cycles at 50％strain),and hydrophobicity,etc.The sensor can monitor human motion repeatedly and stably well,and shows great advantages in flexible wearable devices.
查看更多>>摘要：Tungsten(W)particle-reinforced nickel(Ni)-based composites were fabricated via laser-direct energy de-position(L-DED).The influence of the W particle size on the microstructure and mechanical properties of the deposited samples was systematically studied.The results indicate that refining the W particle size could refine the y-Ni grains and subgrains,thin the(Ni,Cr)4 W interface layer,and increase the disloca-tion density of the intergranular matrix,thus improving the tensile strength and elongation of the L-DED samples.As W particle size decreased from 75 to 150 μm to 6.5-12 μm,the tensile strength and elonga-tion of the deposited samples increased by 150 MPa and 2.9 times to 1347.6±15.7 MPa and 17.5±0.4％,respectively.Based on the properties of the interface(Ni,Cr)4 W,a load-transfer efficiency factor suitable for this composite was proposed and the load-transfer strengthening formula was optimized.A quanti-tative analysis of the strengthening mechanisms was established considering load-transfer strengthening,Hall-Petch strengthening,thermal-mismatch strengthening,and solid-solution strengthening.The calcu-lated contribution of each strengthening mechanism to the yield strength and theoretical calculations were in good agreement with the experimental data.The article breaks the bottleneck of poor plasticity of W particle-reinforced Ni-based composites prepared by L-DED and provides a theoretical basis for the construction design of W particle-reinforced Ni-based composites with excellent mechanical properties.
查看更多>>摘要：Electrical stimulation(ES)can restore motor function after spinal cord injury(SCI).However,traditional intraspinal ES has many disadvantages,such as the need for a complex circuitry device,an external power source,and a second surgery to remove the implant.Piezoelectric materials have received increasing at-tention due to their potential to convert ambient mechanical energy into ES without an external power source or implantation of electrodes.Herein,a novel polydopamine(PDA)coated barium titanate(BaTiO3)nanoparticles(BaTiO3@PDA)incorporated silk fibroin(SF)hydrogel(SFBT)was established.The SFBT hy-drogel was crosslinked by horseradish peroxidase(HRP)/hydrogel peroxide(H2O2)to integrate the piezo-electric potency of BaTiO3 with the thermal sensitivity of HRP/H2O2 for SCI recovery.The hydrogel con-taining 5％(w/v)BaTiO3@PDA nanoparticles(SFBT-5),which was selected for in vivo study,exhibited a short gelation time(5 min),suitable storage modulus(925±35 Pa),and wireless ES(average current of 124 nA).Moreover,Basso-Beattie-Bresnahan(BBB)scores test and footprint analysis demonstrated that the SFBT-5 hydrogel successfully enhanced motor functional recovery of SCI.In histopathological assess-ments,the SFBT-5 hydrogel significantly accelerated spinal cord healing,as indicated by smaller lesion cavities(～16.7％of the SCI group).Meanwhile,the SFBT-5 hydrogel accelerated neurogenesis,facilitated axon regrowth and synapse formation,and promoted remyelination.Overall,this study highlights the potential of piezoelectric hydrogels for SCI regeneration.
查看更多>>摘要：Age hardening is often used to optimize the mechanical properties of as-deformed Mg-based materials in industry,whereas the improvement of strength is usually accompanied by the significant loss of ductility,which hinders the application of Mg-based materials in structural components.In the present work,high strength-ductility synergy(the yield strength of 263±9 MPa,ultimate tensile strength of 398±7 MPa and elongation to fracture of 34％±1％)was realized in as-extruded AlN/AZ91 composites after optimiz-ing aging processes.Microstructural characterization shows that AlN particles induced a large number of geometrically necessary dislocations around the AlN/Mg interface during extrusion,which decreased the nucleation barrier and provided more heterogeneous nucleation sites for γ-Mg17Al12 continuous precipi-tation.Meanwhile,95％of residual dislocations in as-extruded AlN/AZ91 composites were annihilated dur-ing peak-aging,suppressing the growth and coarsening of continuous precipitates.Therefore,high density of nano-sized γ-Mg17Al12 continuous precipitates was produced in as-extruded AlN/AZ91 composites af-ter peak-aging.During tension,gliding dislocations bypassed spherical γ-Mg17Al12 nano-precipitates by Orowan looping rather than cutting mechanism,which induced a strong block on dislocation motion.So high yield strength was mainly attributed to the high density of non-shearable γ-Mg17Al12 nano-precipitates with spherical morphology,which was different from other Mg-Al-based systems.The results of texture evolution and slip trace analysis demonstrated that the suppression of extension twinning and less basal slip was due to the enhanced activity of pyramidal<c+a>slip in as-extruded AlN/AZ91 com-posites after peak-aging during the room temperature tension,meanwhile,the dislocation density of as-extruded AlN/AZ91 composites was significantly decreased during peak-aging,then higher elongation to fracture was achieved.
查看更多>>摘要：Lead-free Bi0.5 Na0.5TiO3(BNT)piezoelectric ceramics have the advantages of large coercive fields and high Curie temperatures.But the improvement of piezoelectric coefficient(d33)is usually accompanied by a huge sacrifice of depolarization temperature(Td).In this work,a well-balanced performance of d33 and Td is achieved in MnO2-doped 0.79(Bi0.sNa0.5TiO3)-0.14(Bi0.5K0.5TiO3)-0.07BaTiO3 ternary ceramics.The in-corporation of 0.25 mol％MnO2 enhances the d33 by more than 40％,while Td remains almost unchanged(i.e.,d33=181 pC/N,Td=184 ℃).X-ray diffraction(XRD)shows that an appropriate fraction of the small axis-ratio ferroelectric phase(pseudo-cubic,Pc)coexists with the long-range ferroelectric phase(tetrag-onal,T)under this MnO2 doping.Piezoelectric force microscopy(PFM)has revealed a special domain configuration,namely large striped and layered macro domains embedded with small nanodomains.This study provides a distinctive avenue to design BNT-based piezoelectric ceramics with high piezoelectric performance and temperature stability.
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