Antimony sulfide(Sb_(2)S_(3))is a promising material for photoelectrochemical(PEC)devices that generate green hydrogen from sunlight and water.In this study,we present a synthesis of high-performance Sb_(2)S_(3)photoa...Antimony sulfide(Sb_(2)S_(3))is a promising material for photoelectrochemical(PEC)devices that generate green hydrogen from sunlight and water.In this study,we present a synthesis of high-performance Sb_(2)S_(3)photoanodes via an interface-engineered hydrothermal growth followed by rapid thermal annealing(RTA).A TiO_(2)interfacial layer plays a crucial role in ensuring homogeneous precursor deposition,enhancing light absorption,and forming efficient heterojunctions with Sb_(2)S_(3),thereby significantly improving charge separation and transport.RTA further improves crystallinity and interfacial contact,resulting in dense and uniform Sb_(2)S_(3)films with enlarged grains and fewer defects.The optimized Sb_(2)S_(3)photoanode achieves a photocurrent density of 2.51 mA/cm^(2)at 1.23 V vs.the reversible hydrogen electrode(RHE),one of the highest reported for Sb_(2)S_(3)without additional catalysts or passivation layers.To overcome the limitations of oxygen evolution reaction(OER),we employ the iodide oxidation reaction(IOR)as an alternative,significantly lowering the overpotential and improving charge transfer kinetics.Consequently,it produces a record photocurrent density of 8.9 mA/cm^(2)at 0.54 V vs.RHE.This work highlights the synergy between TiO_(2)interfacial engineering,RTA-induced crystallization,and IOR-driven oxidation,offering a promising pathway for efficient and scalable PEC hydrogen production.展开更多
Considering the growing pre-lithiation demand for high-performance Si-based anodes and consequent additional costs caused by the strict pre-lithiation environment,developing effective and environmentally stable pre-li...Considering the growing pre-lithiation demand for high-performance Si-based anodes and consequent additional costs caused by the strict pre-lithiation environment,developing effective and environmentally stable pre-lithiation additives is a challenging research hotspot.Herein,interfacial engineered multifunctional Li_(13)Si_(4)@perfluoropolyether(PFPE)/LiF micro/nanoparticles are proposed as anode pre-lithiation additives,successfully constructed with the hybrid interface on the surface of Li_(13)Si_(4)through PFPE-induced nucleophilic substitution.The synthesized multifunctional Li_(13)Si_(4)@PFPE/LiF realizes the integration of active Li compensation,long-term chemical structural stability in air,and solid electrolyte interface(SEI)optimization.In particular,the Li_(13)Si_(4)@PFPE/LiF with a high pre-lithiation capacity(1102.4 mAh g^(-1))is employed in the pre-lithiation Si-based anode,which exhibits a superior initial Coulombic efficiency of 102.6%.Additionally,in situ X-ray diffraction/Raman,density functional theory calculation,and finite element analysis jointly illustrate that PFPE-predominant hybrid interface with modulated abundant highly electronegative F atoms distribution reduces the water adsorption energy and oxidation kinetics of Li_(13)Si_(4)@PFPE/LiF,which delivers a high pre-lithiation capacity retention of 84.39%after exposure to extremely moist air(60%relative humidity).Intriguingly,a LiF-rich mechanically stable bilayer SEI is constructed on anodes through a pre-lithiation-driven regulation for the behavior of electrolyte decomposition.Benefitting from pre-lithiation via multifunctional Li_(13)Si_(4)@PFPE/LiF,the full cell and pouch cell assembled with pre-lithiated anodes operate with long-time stability of 86.5%capacity retention over 200 cycles and superior energy density of 549.9 Wh kg^(-1),respectively.The universal multifunctional pre-lithiation additives provide enlightenment on promoting large-scale applications of pre-lithiation on commercial high-energy-density and long-cycle-life lithium-ion batteries.展开更多
Engineering point defects such as metal and oxygen vacancies play a crucial role in manipulating the electrical,optical,and catalytic properties of oxide semiconductors for solar water splitting.Herein,we synthesized ...Engineering point defects such as metal and oxygen vacancies play a crucial role in manipulating the electrical,optical,and catalytic properties of oxide semiconductors for solar water splitting.Herein,we synthesized nanoporous CuBi_(2)O_(4)(np-CBO)photocathodes and engineered their surface point defects via rapid thermal processing(RTP)in controlled atmospheres(O_(2),N_(2),and vacuum).We found that the O_(2)-RTP treatment of np-CBO increased the charge carrier density effectively without hampering the nanoporous morphology,which was attributed to the formation of copper vacancies(VCu).Further analyses revealed that the amounts of oxygen vacancies(Vo)and Cu^(1+)were reduced simultaneously,and the relative electrochemical active surface area increased after the O_(2)-RTP treatment.Notably,the point defects(VC_(u),Cu^(1+),and Vo)regulated np-CBO achieved a superb water-splitting photocurrent density of-1.81 m A cm^(-2) under simulated sunlight illumination,which is attributed to the enhanced charge transport and transfer properties resulting from the regulated surface point defects.Finally,the reversibility of the formation of the point defects was checked by sequential RTP treatments(O_(2)-N_(2)-O_(2)-N_(2)),demonstrating the strong dependence of photocurrent response on the RTP cycles.Conclusively,the surface point defect engineering via RTP treatment in a controlled atmosphere is a rapid and facile strategy to promote charge transport and transfer properties of photoelectrodes for efficient solar water-splitting.展开更多
Since topological quantum materials may possess interesting properties and promote the application of electronic devices,the search for new topological quantum materials has become the focus and frontier of condensed ...Since topological quantum materials may possess interesting properties and promote the application of electronic devices,the search for new topological quantum materials has become the focus and frontier of condensed matter physics.Currently,it has been found that there are two interesting systems in topological quantum materials:topological superconducting materials and topological magnetic materials.Although research on these materials has made rapid progress,a systematic review of their synthesis,properties,and applications,particularly their synthesis,is still lacking.In this paper,we emphasize the experimental preparation of two typical topological quantum materials and then briefly introduce their potential physical properties and applications.Finally,we provide insights into current and future issues in the study of topological quantum material systems.展开更多
Pure Mg boasting a relatively small corrosion rate is a potential biodegradable metal material for implants.However,its degradation behavior in the complex physiological environment is still a lack of understanding.In...Pure Mg boasting a relatively small corrosion rate is a potential biodegradable metal material for implants.However,its degradation behavior in the complex physiological environment is still a lack of understanding.In this work,we investigated the effect of corrosion product film layers on the degradation behavior of pure Mg in physiological environments.Pure Mg shows a faster corrosion rate in simulated body fluid(SBF)compared to NaCl solution.Hydrogen evolution experiments indicate that the degradation rate of pure Mg in SBF decreases rapidly within the first 12 h but stabilizes afterward.The rapid deposition of low-solubility calcium phosphate on the pure Mg in SBF provides protection to the substrate,resulting in a gradual decrease in the degradation rates.Consequently,the corrosion product film of pure Mg formed in SBF exhibits a layered structure,with the upper layer consisting of dense Ca_(3)(PO_(4))_(2)/Mg_(3)(PO_(4))_(2) and the lower layer consisting of Mg(OH)_(2)/MgO.Electrochemical impedance spectroscopy(EIS)shows that the resistance of the corrosion product film increases over time,indicating gradual strengthening of the corrosion resistance.The 4-week degradation results in the femoral marrow cavity of mice are consistent with the result in SBF in vitro.展开更多
In secondary Al-Si based alloys,microalloying with Mn and Cr can modify harmful platelet-type Alx Fey Siz intermetallic phases to less detrimentalα-Alx(Fe,Mn,Cr)_(y)Siz phase(script or polygonal morphologies).However...In secondary Al-Si based alloys,microalloying with Mn and Cr can modify harmful platelet-type Alx Fey Siz intermetallic phases to less detrimentalα-Alx(Fe,Mn,Cr)_(y)Siz phase(script or polygonal morphologies).However,theα-Alx(Fe,Mn,Cr)_(y)Siz phase morphology,phase composition and the addition of Fecorrecting elements can be influenced by solidification conditions.Therefore,this research is aimed to highlight the morphological evolution and mechanisms ofα-Alx(Fe,Mn,Cr)_(y)Si_(z)phase in a Cr added Al-9%Si-1%Fe-0.2%Cr(all weight percentage thereafter,unless otherwise stated)alloy with varying Mn concentrations(0.25%,0.5%,and 0.8%).Microstructure evolution of Fe intermetallic phases is investi-gated under different casting conditions using a wedge-shaped die,Cu-chill block and melt quenching experiments.Thermodynamic simulations have been performed using CALculation of PHAse Diagrams(CALPHAD)method and compared with the experimental results for phase composition and formation temperatures ofα-Alx(Fe,Mn,Cr)_(y)Siz phase.The results indicated that for 0.25Mn-0.2Cr addition to Al-9Si-1Fe alloy,compact morphology containing polygonal phases are formed in Cu-chill casting,while the wedge castings predominantly show a mixed structure with platelets and script type morphologies.Tensile tests revealed a higher elongation value of 6.6%for mixed structure with platelet and script phases,which is decreased to 4.2%for polygonal phases in Al-9Si-1Fe-0.2Cr-0.25Mn alloy.This study highlights the importance of solidification conditions on morphologies of Fe-intermetallic phases and the mechanical properties by comparing selected literature relevant to high pressure die-casting process.展开更多
In engineering structures, the application of advanced alloys, such as the VCoNi medium-entropy alloy (VCoNi-MEA), with remarkable tensile strength (> 1 GPa) and superior ductility necessitates the employment of di...In engineering structures, the application of advanced alloys, such as the VCoNi medium-entropy alloy (VCoNi-MEA), with remarkable tensile strength (> 1 GPa) and superior ductility necessitates the employment of dissimilar joints. This study pioneers the dissimilar joining of VCoNi-MEA and 17–4 precipitation hardening stainless steel (17–4PH STS) using state-of-the-art green laser beam welding (LBW). To evaluate and optimize the experimental parameters, two welding speeds (200 and 300 mm/s) along with post-weld heat treatment (PWHT) were incorporated. High-quality welded joints with a single-phase face-centered cubic (FCC) structure in the fusion zone (FZ), minimal precipitates (< 1.6 %), and no visible cracks were successfully created. The LBW process demonstrated effective low-heat input characteristics, evident from a considerably narrow heat-affected zone (HAZ). Control over FZ width and grain size was achieved, measuring 600 and 112 µm at low welding speed and 250 and 49 µm at high welding speed, respectively, significantly lower than previous studies. A remarkably high yield strength (YS) of ∼620 MPa and ultimate tensile strength (UTS) up to 845 MPa were observed in the as-welded conditions, improving to ∼645 and 875 MPa, respectively, after PWHT. This enhancement in mechanical properties is primarily attributed to lattice friction induced by V addition. PWHT also improved joint ductility, increasing from 3.5 % to 8.6 % (low-speed) and from 6.3 % to 9.2 % (high-speed). The reduction in crystallographic orientation achieved using a higher welding speed and PWHT emerged as a major reason for improved mechanical properties. Slip-based deformation mechanisms dominated across all conditions, featuring crystallographically aligned slip bands. Interactions between existing and additional slip bands formed a dense dislocation network crucial for enhanced elongation after PWHT. Thermodynamic parameters elucidating phase stability in the observed FZs and contributions to superior YS were calculated and comprehensively discussed.展开更多
Preferential oxidation of CO is an effective process to clean up CO in hydrogen for proton exchange membrane fuel cells(PEMFCs).Herein,we synthesis a highly efficient catalyst for preferential oxidation(PROX)of CO thr...Preferential oxidation of CO is an effective process to clean up CO in hydrogen for proton exchange membrane fuel cells(PEMFCs).Herein,we synthesis a highly efficient catalyst for preferential oxidation(PROX)of CO through the deposition of Ru/Ir nanojunctions on Fe_(2)O_(3) nanoparticles.The as-prepared catalyst shows 90%CO conversion at 80℃ within the working temperature of PEMFCs and the total CO conversion in the temperature range of 140℃ to 160℃under gas flow velocity of 36000 mL·g^(−1)h^(−1) while maintaining good stability for 24 h.Density functional theory calculations reveal that the substrate Fe_(2)O_(3) not only serves as a source of lattice oxygen atoms for the catalytic process but also acts as an electron acceptor from Ru/Ir,thereby regulating its valence state.This regulation is beneficial for the adsorption of reaction intermediates and reduces the activation energy of PROX.展开更多
This study comprehensively investigates the effects of annealing on the structural,electrochemical properties and passivation film characteristics of Ti_(20)Zr_(20)Hf_(20)Be_(20)Ni_(20)(at%)high-entropy metallic glass...This study comprehensively investigates the effects of annealing on the structural,electrochemical properties and passivation film characteristics of Ti_(20)Zr_(20)Hf_(20)Be_(20)Ni_(20)(at%)high-entropy metallic glass(HE-MG).Subjected to various annealing temperatures,the samples were analyzed in a 3.5 wt%NaCl solution to evaluate changes in their microstructure and assess their corrosion resistance.Findings reveal that the HE-MG undergoes multistage crystallization,displaying an amorphous matrix integrated with face centered cubic(FCC)and Ni_(7)Zr_(2)phases between 420 and 500℃,indicating robust thermal stability.Electrochemical assessments identify a critical temperature threshold:Below the glass transition temperature(Tg),the HE-MG maintains excellent corrosion resistance,promoting stable passivation layers.Above Tg,enhanced long-range atomic rearrangement during relaxation increases passivation layer defects and significantly diminishes corrosion resistance.X-ray photoelectron spectroscopy(XPS)analyses show that the primary components of the passivation layer are TiO_(2),ZrO_(2),HfO_(2)and BeO.Increased annealing temperatures lead to enhanced Be and Ni content and decreased Ti,Zr and Hf.Additionally,high mixing entropy and significant atomic size mismatch suppress long-range atomic rearrangement and crystallization.The crystallization begins above Tg by_(20)℃,with crystalline phases evenly distributed within the matrix without drastically affecting corrosion resistance.This investigation highlights the impact of thermal treatment on the properties of HE-MG,contributing valuable insights into optimizing their performance and applications.展开更多
Al_(2)O_(3)and MgO serve as the primary gangue components in sintered ores,and they are critical for the formation of CaO-Fe_(2)O_(3)-xAl_(2)O_(3)(wt%,C-F-xA)and CaO-Fe_(2)O_(3)-xM gO(wt%,C-F-xM)systems,respectively.I...Al_(2)O_(3)and MgO serve as the primary gangue components in sintered ores,and they are critical for the formation of CaO-Fe_(2)O_(3)-xAl_(2)O_(3)(wt%,C-F-xA)and CaO-Fe_(2)O_(3)-xM gO(wt%,C-F-xM)systems,respectively.In this study,a nonisothermal crystallization thermodynamics behavior of C-F-xA and C-F-xM systems was examined using differential scanning calorimetry,and a phase identification and microstructure analysis for C-F-xA and C-F-xM systems were carried out by X-ray diffraction and scanning electron microscopy.Results showed that in C-F-2A and C-F-2M systems,the increased cooling rates promoted the precipitation of CaFe_(2)O_(4)(CF)but inhibited the formation of Ca_(2)Fe_(2)O_(5)(C2F).In addition,C-F-2A system exhibited a lower theoretical initial crystallization temperature(1566 K)compared to the C-F system(1578 K).This temperature further decreases to 1554 K and 1528 K in the C-F-4A and C-F-8A systems,respectively.However,in C-F-xM system,the increased MgO content raised the crystallization temperature.This is because that the enhanced precipitation of MF(a spinel phase mainly comprised Fe_(3)O_(4)and MgFe_(2)O_(4))and C2F phases suppressed the CF precipitation reaction.In kinetic calculations,the Ozawa method revealed the apparent activation energies of the C-F-2A and C-F-2M systems.Malek's method revealed that the crystallization process in C-F-2A system initially followed a logarithmic law(lnαor lnα2),later transitioning to a reaction order law((1-α)-1or(1-α)^(-1/2),n=2/3)or the lnα2function of the exponential law.In C-F-2M system,it consistently followed the sequencef(α)=(1-α)^(2)(αis the crystallization conversion rate;n is the Avrami constant;?(α)is the differential equations for the model function of C_(2)F and CF crystallization processes).展开更多
The poor corrosion resistance of magnesium(Mg)and its alloys limits their application in various fields.Micro arc oxidation(MAO)coatings can improve the corrosion resistance,but the pore defects and low surface hardne...The poor corrosion resistance of magnesium(Mg)and its alloys limits their application in various fields.Micro arc oxidation(MAO)coatings can improve the corrosion resistance,but the pore defects and low surface hardness make them susceptible to wear and accelerated corrosion during usage.In this study,a ZrO_(2)nanoparticles doped-MAO coating is prepared on the ZK61 Mg alloy by utilizing an MgF_(2)passivation layer to prevent ablation.The ZrO_(2)nanoparticles re-melt and precipitate due to local discharging,which produces evenly dispersed nanocrystals in the MAO coating.As a result,the hardness of the MAO coating with the appropriate ZrO_(2)concentration increases by over 10 times,while the wear rate decreases and corrosion resistance increases.With increasing ZrO_(2)concentrations,the corrosion potentials increase from−1.528 V of the bare ZK61 Mg alloy to−1.184 V,the corrosion current density decreases from 1.065×10^(–4)A cm^(–2)to 3.960×10^(–8)A cm^(–2),and the charge transfer resistance increases from 3.41×10^(2)Ωcm^(2)to 6.782×10^(5)Ωcm^(2).Immersion tests conducted in a salt solution for 28 d reveal minimal corrosion in contrast to severe corrosion on the untreated ZK61 Mg alloy.ZrO_(2)nanoparticles improve the corrosion resistance of MAO coatings by sealing pores and secondary strengthening of the corrosion product layer.展开更多
Intrinsic topological superconductors have garnered significant attention for their potential to harbor novel quantum phenomena.However,the limited availability of suitable material systems has hindered progress in th...Intrinsic topological superconductors have garnered significant attention for their potential to harbor novel quantum phenomena.However,the limited availability of suitable material systems has hindered progress in this field.Here,we present the synthesis and characterization of high-quality self-assembled SnS/TaS_(2)(SnTaS_(3))superlattice,which exhibits superconductivity alongside non-trivial band topology.Temperature-dependent magnetization susceptibility and electrical transport results confirm SnTaS_(3) as a type-Ⅱ superconductor with a critical transition temperature Tc of 3 K.Interestingly,this superconductivity can be turned off via an innovative solid proton gate technique,and a new superconducting state with a Tc of~2.3 K emerges when the gating voltage reaches-9.47 V.Heat capacity measurements reveal strong electronic correlations within this material,which is further supported by angle-resolved photoemission spectroscopy and first-principles calculations,underscoring the effect of topological flat bands and Van Hove singularity.Our research introduces a promising self-assembled material platform,adeptly positioned to delve into the quest for topological superconductors.展开更多
Additive manufacturing(AM) of Ni-base superalloy components can lead to a significant reduction of weight in aerospace applications. AM of IN718 by selective laser melting results in a very fine dendritic microstructu...Additive manufacturing(AM) of Ni-base superalloy components can lead to a significant reduction of weight in aerospace applications. AM of IN718 by selective laser melting results in a very fine dendritic microstructure with a high dislocation density due to the fast solidification process. The complex phase composition of this alloy, with three different types of precipitates and high residual stresses, necessitates adjustment of the conventional heat treatment for AM parts. To find an optimized heat treatment, the microstructures and mechanical properties of differently solution heat-treated samples were investigated by transmission and scanning electron microscopy, including electron backscatter diffraction, and compression tests. After a solution heat treatment(SHT), the Nb-rich Laves phase dissolves and the dislocation density is reduced, which eliminates the dendritic substructure. SHT at 930 or 954°C leads to the precipitation of the δ-phase, which reduces the volume fraction of the strengthening γ′-and γ′′-phases formed during the subsequent two stage aging treatment. With a higher SHT temperature of 1000°C, where no δ-phase is precipitated, higher γ′ and γ′′ volume fractions are achieved, which results in the optimum strength of all of the solution heat treated conditions.展开更多
In the present work,AZ91 alloy was successfully processed by equal channel angular pressing(ECAP)for up to 16 passes and rolling(R)for multiple passes with a total reduction of 75%in addition to a combination method w...In the present work,AZ91 alloy was successfully processed by equal channel angular pressing(ECAP)for up to 16 passes and rolling(R)for multiple passes with a total reduction of 75%in addition to a combination method with ECAP plus rolling(ECAP+R).The effects of various processes(ECAP,R and ECAP+R)on microstructure evolution were analyzed and the influence of ECAP process on the rolling performance was examined.The result shows that ECAP contributed to a homogenous grain structure and formed a texture with higher Schmidt factors that was easy for rolling.A plate with smoother surface and reduced edge cracks was observed in the ECAP+R process than in the single R process.Although the microstructure of the alloy was similar after ECAP+R and R process,the sample of ECAP+R was more refined and had stronger second phase precipitation than the sample of R,which resulted in better rolling characteristics,along with the external surfaces.展开更多
Binder jet printing(BJP)is a state-of-the-art additive manufacturing technique for producing porous magnesium structures.Porous MgZn-Zr based BJP samples were assessed for corrosion performance in simulated body fluid...Binder jet printing(BJP)is a state-of-the-art additive manufacturing technique for producing porous magnesium structures.Porous MgZn-Zr based BJP samples were assessed for corrosion performance in simulated body fluids by electrochemical and hydrogen evolution measurements.The corrosion rates of the BJP specimens were significantly higher than solid controls,even after accounting for their larger surface areas,suggesting that the BJP microstructure is detrimental to corrosion performance.X-ray computed tomography revealed nonuniform corrosion within the porous structure,with corrosion products forming on the pore walls.Impregnating the pores with hydroxyapatite or polymers greatly improved the corrosion resistance of the BJP samples.展开更多
Silicon (Si) is a promising anode material for next-generation high-energy lithium-ion batteries (LIBs) due to its high capacity.However,the large volumetric expansion,poor ion conductivity and unstable solid electrol...Silicon (Si) is a promising anode material for next-generation high-energy lithium-ion batteries (LIBs) due to its high capacity.However,the large volumetric expansion,poor ion conductivity and unstable solid electrolyte interface (SEI) lead to rapid capacity fading and low rate performance.Herein,we report Si nitride (SiN) comprising stoichiometric Si_(3)N_(4) and Li-active anazotic SiN_(x) coated porous Si (p-Si@SiN)for high-performance anodes in LIBs.The ant-nest-like porous Si consisting of 3D interconnected Si nanoligaments and bicontinuous nanopores prevents pulverization and accommodates volume expansion during cycling.The Si_(3)N_(4) offers mechanically protective coating to endow highly structural integrity and inhibit superfluous formation of SEI.The fast ion conducting Li_(3)N generated in situ from lithiation of active SiN_(x) facilitates Li ion transport.Consequently,the p-Si@SiN anode has appealing electrochemical properties such as a high capacity of 2180 mAh g^(-1)at 0.5 A g^(-1) with 84%capacity retention after 200cycles and excellent rate capacity with discharge capacity of 721 mAh g^(-1) after 500 cycles at 5.0 A g^(-1).This work provides insights into the rational design of active/inactive nanocoating on Si-based anode materials for fast-charging and highly stable LIBs.展开更多
Conventionally,Te has primarily been used to improve the machinability of steel and its alloys.In this work,Te was used to refine the grains of an oxide-dispersion-strengthened(ODS)steel produced by additive manufactu...Conventionally,Te has primarily been used to improve the machinability of steel and its alloys.In this work,Te was used to refine the grains of an oxide-dispersion-strengthened(ODS)steel produced by additive manufacturing(AM)with fixed processing parameters.Addition of Te to the raw powder produced an ODS steel with a fine-grained microstructure,in contrast to the ODS steel manufactured without Te.Moreover,the addition of Te resulted in superior yield strength and ultimate tensile strength,which was attributed to the combined effects of grain refinement and the finer nanoparticles(NPs)composed of Terich composite NPs and Cr-rich NPs.For the first time,the AM technique was used to obtain grain and nanoparticle sizes of~3.4μm and 6 nm,respectively,from the Te-added ODS steel.展开更多
In the current study,a modified sol-gel route was used to produce undoped and Sm^(3+)doped(1 mol%,3 mol%and 5 mol%)ZnO nanoparticles(NPs).The study of opto-structural properties of Sm^(3+)doped NPs was carried out bot...In the current study,a modified sol-gel route was used to produce undoped and Sm^(3+)doped(1 mol%,3 mol%and 5 mol%)ZnO nanoparticles(NPs).The study of opto-structural properties of Sm^(3+)doped NPs was carried out both experimentally and theoretically.Complete dissolution of Sm^(3+)ions into the ZnO lattice is obviously seen from X-ray diffraction(XRD)analysis.Morphological evolution with doping was studied using field emission scanning electron microscopy(FESEM)and transmission electron microscopy(TEM).X-ray photoelectron spectroscopy(XPS)was carried out to confirm the prese nce of Sm~(3+)on the doped NPs.Increasing dopant quantity results in a redshift of the NPs along with a reduction in bandgap with increasing abso rption in the visible range,and a minimum of 3.18 eV of optical bandgap for Zn_(0.97)Sm_(0.03)O is found.Photoluminescence spectroscopy reveals a drop in the recombination rate of electron-hole with increasing doping content till 3 mol%,followed by an increase of Zn_(0.95)Sm_(0.05)O.Photogenerated electron-hole pair recombination is revealed by the orange band in the luminescence spectra.Theoretical analysis was also carried out with density functional theory(DFT).This work also unfolds the fundamental understanding of the structural properties of the synthesized NPs to enhance photocatalytic activity successfully.Later,photocatalytic activity for the optimum composition,i.e.,3 mol%,was assessed experimentally.展开更多
Transition metal sulfides are emerging as promising electrode materials for energy storage and conversion.In this work,hierarchical FeS2/C nanospheres are synthesized through a controllable solvothermal method followe...Transition metal sulfides are emerging as promising electrode materials for energy storage and conversion.In this work,hierarchical FeS2/C nanospheres are synthesized through a controllable solvothermal method followed by the annealing process.Spherical FeS2 core is homogeneously coated by thin carbon shell.The hierarchical nanostructure and carbon coating can enhance electron transfer and accommodate the stress originated from the volume change as well as suppress the shuttle effect of polysulfide.Consequently,as the cathode material of lithium ion batteries(LIBs),the FeS2/C nanospheres exhibit high reversible capacity of 676 m Ahg^-1 and excellent cycling life with the capacity retention of 97.1%after100 cycles.In addition,even at the high current density of 1.8 C,a reversible capacity of 437 m Ahg^-1 is obtained for the FeS2/C nanospheres,demonstrating its great prospect for practical applications in highperformance LIBs.展开更多
The effect of Gd content on the microstructure and tensile properties of as-cast Mg-Sm-Zn-Zr alloy has been systematically investigated.In the Mg-3Sm-0.5Zn-0.5Zr alloy, the intermetallic compounds with multiple morpho...The effect of Gd content on the microstructure and tensile properties of as-cast Mg-Sm-Zn-Zr alloy has been systematically investigated.In the Mg-3Sm-0.5Zn-0.5Zr alloy, the intermetallic compounds with multiple morphologies are identified as Mg_(3)Sm phase. In addition to Mg_(3)RE phase, Mg_(5)RE phase originated from Gd addition is observed in Gd-modified alloys. It should be noted that the lattice parameters of all the observed intermetallic compounds are significantly reduced by Zn segregation. The segregation behavior of Zn in Mg_(3)Sm phase is inhibited to some extent by Gd addition due to the electronegativity difference between Sm/Gd and Zn elements. In addition, the increased Gd content effectively leads to much more accumulation of solute atoms in front of the liquid-solid interface during solidification, which can prominently promote nucleation in liquid region and then refine grains. The tensile yield stress of the present alloys is thus improved with increasing Gd addition. Finally, Gd-modified alloys exhibit significantly age-hardening effect, which can be mainly attributed to the high-volume fraction and high density nano-scale precipitates.展开更多
基金supported by the National Research Foundation of Korea(NRF)grant fu nded by the Korean government(MSIT)(No.RS-2024-00335976)。
文摘Antimony sulfide(Sb_(2)S_(3))is a promising material for photoelectrochemical(PEC)devices that generate green hydrogen from sunlight and water.In this study,we present a synthesis of high-performance Sb_(2)S_(3)photoanodes via an interface-engineered hydrothermal growth followed by rapid thermal annealing(RTA).A TiO_(2)interfacial layer plays a crucial role in ensuring homogeneous precursor deposition,enhancing light absorption,and forming efficient heterojunctions with Sb_(2)S_(3),thereby significantly improving charge separation and transport.RTA further improves crystallinity and interfacial contact,resulting in dense and uniform Sb_(2)S_(3)films with enlarged grains and fewer defects.The optimized Sb_(2)S_(3)photoanode achieves a photocurrent density of 2.51 mA/cm^(2)at 1.23 V vs.the reversible hydrogen electrode(RHE),one of the highest reported for Sb_(2)S_(3)without additional catalysts or passivation layers.To overcome the limitations of oxygen evolution reaction(OER),we employ the iodide oxidation reaction(IOR)as an alternative,significantly lowering the overpotential and improving charge transfer kinetics.Consequently,it produces a record photocurrent density of 8.9 mA/cm^(2)at 0.54 V vs.RHE.This work highlights the synergy between TiO_(2)interfacial engineering,RTA-induced crystallization,and IOR-driven oxidation,offering a promising pathway for efficient and scalable PEC hydrogen production.
基金Huaiyu Shao acknowledges the Shenzhen-Hong Kong-Macao Science and Technology Plan Project(Category C)(Grant No.SGDX20220530111004028)the Macao Science and Technology Development Fund(FDCT)for funding(FDCT No.0013/2024/RIB1,FDCT-MOST joint project No.0026/2022/AMJ and No.006/2022/ALC of the Macao Centre for Research and Development in Advanced Materials[2022–2024])+2 种基金the Multi-Year Research Grant(MYRG)from University of Macao(project No.MYRG-GRG2023-00140-IAPME-UMDF and No.MYRG-GRG2024-00206-IAPME)Natural Science Foundation of Guangdong Province(Grant No.2023A1515010765)Science and Technology Program of Guangdong Province of China(Grant No.2023A0505030001)。
文摘Considering the growing pre-lithiation demand for high-performance Si-based anodes and consequent additional costs caused by the strict pre-lithiation environment,developing effective and environmentally stable pre-lithiation additives is a challenging research hotspot.Herein,interfacial engineered multifunctional Li_(13)Si_(4)@perfluoropolyether(PFPE)/LiF micro/nanoparticles are proposed as anode pre-lithiation additives,successfully constructed with the hybrid interface on the surface of Li_(13)Si_(4)through PFPE-induced nucleophilic substitution.The synthesized multifunctional Li_(13)Si_(4)@PFPE/LiF realizes the integration of active Li compensation,long-term chemical structural stability in air,and solid electrolyte interface(SEI)optimization.In particular,the Li_(13)Si_(4)@PFPE/LiF with a high pre-lithiation capacity(1102.4 mAh g^(-1))is employed in the pre-lithiation Si-based anode,which exhibits a superior initial Coulombic efficiency of 102.6%.Additionally,in situ X-ray diffraction/Raman,density functional theory calculation,and finite element analysis jointly illustrate that PFPE-predominant hybrid interface with modulated abundant highly electronegative F atoms distribution reduces the water adsorption energy and oxidation kinetics of Li_(13)Si_(4)@PFPE/LiF,which delivers a high pre-lithiation capacity retention of 84.39%after exposure to extremely moist air(60%relative humidity).Intriguingly,a LiF-rich mechanically stable bilayer SEI is constructed on anodes through a pre-lithiation-driven regulation for the behavior of electrolyte decomposition.Benefitting from pre-lithiation via multifunctional Li_(13)Si_(4)@PFPE/LiF,the full cell and pouch cell assembled with pre-lithiated anodes operate with long-time stability of 86.5%capacity retention over 200 cycles and superior energy density of 549.9 Wh kg^(-1),respectively.The universal multifunctional pre-lithiation additives provide enlightenment on promoting large-scale applications of pre-lithiation on commercial high-energy-density and long-cycle-life lithium-ion batteries.
基金supported by the Basic Science Research Program through the National Research Foundation of Korea,funded by the Ministry of Science,ICT,and Future Planning(NRF Award No.NRF-2019R1A2C2002024 and 2021R1A4A1031357)supported by the Basic Science Research Program through NRF funded by the Ministry of Education(NRF Award No.NRF2020R1A6A1A03043435)。
文摘Engineering point defects such as metal and oxygen vacancies play a crucial role in manipulating the electrical,optical,and catalytic properties of oxide semiconductors for solar water splitting.Herein,we synthesized nanoporous CuBi_(2)O_(4)(np-CBO)photocathodes and engineered their surface point defects via rapid thermal processing(RTP)in controlled atmospheres(O_(2),N_(2),and vacuum).We found that the O_(2)-RTP treatment of np-CBO increased the charge carrier density effectively without hampering the nanoporous morphology,which was attributed to the formation of copper vacancies(VCu).Further analyses revealed that the amounts of oxygen vacancies(Vo)and Cu^(1+)were reduced simultaneously,and the relative electrochemical active surface area increased after the O_(2)-RTP treatment.Notably,the point defects(VC_(u),Cu^(1+),and Vo)regulated np-CBO achieved a superb water-splitting photocurrent density of-1.81 m A cm^(-2) under simulated sunlight illumination,which is attributed to the enhanced charge transport and transfer properties resulting from the regulated surface point defects.Finally,the reversibility of the formation of the point defects was checked by sequential RTP treatments(O_(2)-N_(2)-O_(2)-N_(2)),demonstrating the strong dependence of photocurrent response on the RTP cycles.Conclusively,the surface point defect engineering via RTP treatment in a controlled atmosphere is a rapid and facile strategy to promote charge transport and transfer properties of photoelectrodes for efficient solar water-splitting.
基金supported by National Natural Science Foundation of China(52373309).
文摘Since topological quantum materials may possess interesting properties and promote the application of electronic devices,the search for new topological quantum materials has become the focus and frontier of condensed matter physics.Currently,it has been found that there are two interesting systems in topological quantum materials:topological superconducting materials and topological magnetic materials.Although research on these materials has made rapid progress,a systematic review of their synthesis,properties,and applications,particularly their synthesis,is still lacking.In this paper,we emphasize the experimental preparation of two typical topological quantum materials and then briefly introduce their potential physical properties and applications.Finally,we provide insights into current and future issues in the study of topological quantum material systems.
基金supported by the National Natural Science Foundation of China(52127801)Postdoctoral Fellowship Program of CPSF under Grant Number GZC20231545,China Postdoctoral Science Foundation(2024T170557 and 2023M742224)+1 种基金Shanghai Post-doctoral Excellence Program(No.2023440)City University of Hong Kong Donation Grants(DON-RMG No.9229021 and 9220061).
文摘Pure Mg boasting a relatively small corrosion rate is a potential biodegradable metal material for implants.However,its degradation behavior in the complex physiological environment is still a lack of understanding.In this work,we investigated the effect of corrosion product film layers on the degradation behavior of pure Mg in physiological environments.Pure Mg shows a faster corrosion rate in simulated body fluid(SBF)compared to NaCl solution.Hydrogen evolution experiments indicate that the degradation rate of pure Mg in SBF decreases rapidly within the first 12 h but stabilizes afterward.The rapid deposition of low-solubility calcium phosphate on the pure Mg in SBF provides protection to the substrate,resulting in a gradual decrease in the degradation rates.Consequently,the corrosion product film of pure Mg formed in SBF exhibits a layered structure,with the upper layer consisting of dense Ca_(3)(PO_(4))_(2)/Mg_(3)(PO_(4))_(2) and the lower layer consisting of Mg(OH)_(2)/MgO.Electrochemical impedance spectroscopy(EIS)shows that the resistance of the corrosion product film increases over time,indicating gradual strengthening of the corrosion resistance.The 4-week degradation results in the femoral marrow cavity of mice are consistent with the result in SBF in vitro.
基金supported by the U.S.Department of Energy’s Office of Energy Efficiency and Renewable Energy(EERE)under the Advanced Manufacturing Office Award Number DE-EE0007897。
文摘In secondary Al-Si based alloys,microalloying with Mn and Cr can modify harmful platelet-type Alx Fey Siz intermetallic phases to less detrimentalα-Alx(Fe,Mn,Cr)_(y)Siz phase(script or polygonal morphologies).However,theα-Alx(Fe,Mn,Cr)_(y)Siz phase morphology,phase composition and the addition of Fecorrecting elements can be influenced by solidification conditions.Therefore,this research is aimed to highlight the morphological evolution and mechanisms ofα-Alx(Fe,Mn,Cr)_(y)Si_(z)phase in a Cr added Al-9%Si-1%Fe-0.2%Cr(all weight percentage thereafter,unless otherwise stated)alloy with varying Mn concentrations(0.25%,0.5%,and 0.8%).Microstructure evolution of Fe intermetallic phases is investi-gated under different casting conditions using a wedge-shaped die,Cu-chill block and melt quenching experiments.Thermodynamic simulations have been performed using CALculation of PHAse Diagrams(CALPHAD)method and compared with the experimental results for phase composition and formation temperatures ofα-Alx(Fe,Mn,Cr)_(y)Siz phase.The results indicated that for 0.25Mn-0.2Cr addition to Al-9Si-1Fe alloy,compact morphology containing polygonal phases are formed in Cu-chill casting,while the wedge castings predominantly show a mixed structure with platelets and script type morphologies.Tensile tests revealed a higher elongation value of 6.6%for mixed structure with platelet and script phases,which is decreased to 4.2%for polygonal phases in Al-9Si-1Fe-0.2Cr-0.25Mn alloy.This study highlights the importance of solidification conditions on morphologies of Fe-intermetallic phases and the mechanical properties by comparing selected literature relevant to high pressure die-casting process.
基金supported by the Nano&Material Technology Development Program through the National Research Foundation of Korea(NRF)funded by the Ministry of Science and ICT(Nos.RS-2023-00234757 and RS-2024-00402289)。
文摘In engineering structures, the application of advanced alloys, such as the VCoNi medium-entropy alloy (VCoNi-MEA), with remarkable tensile strength (> 1 GPa) and superior ductility necessitates the employment of dissimilar joints. This study pioneers the dissimilar joining of VCoNi-MEA and 17–4 precipitation hardening stainless steel (17–4PH STS) using state-of-the-art green laser beam welding (LBW). To evaluate and optimize the experimental parameters, two welding speeds (200 and 300 mm/s) along with post-weld heat treatment (PWHT) were incorporated. High-quality welded joints with a single-phase face-centered cubic (FCC) structure in the fusion zone (FZ), minimal precipitates (< 1.6 %), and no visible cracks were successfully created. The LBW process demonstrated effective low-heat input characteristics, evident from a considerably narrow heat-affected zone (HAZ). Control over FZ width and grain size was achieved, measuring 600 and 112 µm at low welding speed and 250 and 49 µm at high welding speed, respectively, significantly lower than previous studies. A remarkably high yield strength (YS) of ∼620 MPa and ultimate tensile strength (UTS) up to 845 MPa were observed in the as-welded conditions, improving to ∼645 and 875 MPa, respectively, after PWHT. This enhancement in mechanical properties is primarily attributed to lattice friction induced by V addition. PWHT also improved joint ductility, increasing from 3.5 % to 8.6 % (low-speed) and from 6.3 % to 9.2 % (high-speed). The reduction in crystallographic orientation achieved using a higher welding speed and PWHT emerged as a major reason for improved mechanical properties. Slip-based deformation mechanisms dominated across all conditions, featuring crystallographically aligned slip bands. Interactions between existing and additional slip bands formed a dense dislocation network crucial for enhanced elongation after PWHT. Thermodynamic parameters elucidating phase stability in the observed FZs and contributions to superior YS were calculated and comprehensively discussed.
基金financially supported by the National Natural Science Foundation of China(No.22072140,No.22272155,and No.22102169)the National Key R&D Program of China(No.2021YFA1600202)。
文摘Preferential oxidation of CO is an effective process to clean up CO in hydrogen for proton exchange membrane fuel cells(PEMFCs).Herein,we synthesis a highly efficient catalyst for preferential oxidation(PROX)of CO through the deposition of Ru/Ir nanojunctions on Fe_(2)O_(3) nanoparticles.The as-prepared catalyst shows 90%CO conversion at 80℃ within the working temperature of PEMFCs and the total CO conversion in the temperature range of 140℃ to 160℃under gas flow velocity of 36000 mL·g^(−1)h^(−1) while maintaining good stability for 24 h.Density functional theory calculations reveal that the substrate Fe_(2)O_(3) not only serves as a source of lattice oxygen atoms for the catalytic process but also acts as an electron acceptor from Ru/Ir,thereby regulating its valence state.This regulation is beneficial for the adsorption of reaction intermediates and reduces the activation energy of PROX.
基金supported by the National Key R&D Program of China(No.2021YFE0100600)the National Natural Science Foundation of China(No.52371154)+2 种基金Guangdong Basic and Applied Basic Research Foundation(No.2023A1515012158)the Opening Project of the Key Laboratory of CNC Equipment Reliability,Ministry of Education,Jilin University(No.JLU-cncr-202307)the Knowledge Innovation Program of Wuhan-Basic Research(No.2022010801010087).
文摘This study comprehensively investigates the effects of annealing on the structural,electrochemical properties and passivation film characteristics of Ti_(20)Zr_(20)Hf_(20)Be_(20)Ni_(20)(at%)high-entropy metallic glass(HE-MG).Subjected to various annealing temperatures,the samples were analyzed in a 3.5 wt%NaCl solution to evaluate changes in their microstructure and assess their corrosion resistance.Findings reveal that the HE-MG undergoes multistage crystallization,displaying an amorphous matrix integrated with face centered cubic(FCC)and Ni_(7)Zr_(2)phases between 420 and 500℃,indicating robust thermal stability.Electrochemical assessments identify a critical temperature threshold:Below the glass transition temperature(Tg),the HE-MG maintains excellent corrosion resistance,promoting stable passivation layers.Above Tg,enhanced long-range atomic rearrangement during relaxation increases passivation layer defects and significantly diminishes corrosion resistance.X-ray photoelectron spectroscopy(XPS)analyses show that the primary components of the passivation layer are TiO_(2),ZrO_(2),HfO_(2)and BeO.Increased annealing temperatures lead to enhanced Be and Ni content and decreased Ti,Zr and Hf.Additionally,high mixing entropy and significant atomic size mismatch suppress long-range atomic rearrangement and crystallization.The crystallization begins above Tg by_(20)℃,with crystalline phases evenly distributed within the matrix without drastically affecting corrosion resistance.This investigation highlights the impact of thermal treatment on the properties of HE-MG,contributing valuable insights into optimizing their performance and applications.
基金financially supported by the National Natural Science Foundation of China(Nos.52204331 and 52374315)the Major Industrial Innovation Plan of Anhui Provincial Development and the Reform Commission,China(No.AHZDCYCX-LSDT2023-01)。
文摘Al_(2)O_(3)and MgO serve as the primary gangue components in sintered ores,and they are critical for the formation of CaO-Fe_(2)O_(3)-xAl_(2)O_(3)(wt%,C-F-xA)and CaO-Fe_(2)O_(3)-xM gO(wt%,C-F-xM)systems,respectively.In this study,a nonisothermal crystallization thermodynamics behavior of C-F-xA and C-F-xM systems was examined using differential scanning calorimetry,and a phase identification and microstructure analysis for C-F-xA and C-F-xM systems were carried out by X-ray diffraction and scanning electron microscopy.Results showed that in C-F-2A and C-F-2M systems,the increased cooling rates promoted the precipitation of CaFe_(2)O_(4)(CF)but inhibited the formation of Ca_(2)Fe_(2)O_(5)(C2F).In addition,C-F-2A system exhibited a lower theoretical initial crystallization temperature(1566 K)compared to the C-F system(1578 K).This temperature further decreases to 1554 K and 1528 K in the C-F-4A and C-F-8A systems,respectively.However,in C-F-xM system,the increased MgO content raised the crystallization temperature.This is because that the enhanced precipitation of MF(a spinel phase mainly comprised Fe_(3)O_(4)and MgFe_(2)O_(4))and C2F phases suppressed the CF precipitation reaction.In kinetic calculations,the Ozawa method revealed the apparent activation energies of the C-F-2A and C-F-2M systems.Malek's method revealed that the crystallization process in C-F-2A system initially followed a logarithmic law(lnαor lnα2),later transitioning to a reaction order law((1-α)-1or(1-α)^(-1/2),n=2/3)or the lnα2function of the exponential law.In C-F-2M system,it consistently followed the sequencef(α)=(1-α)^(2)(αis the crystallization conversion rate;n is the Avrami constant;?(α)is the differential equations for the model function of C_(2)F and CF crystallization processes).
基金supported by the Postdoctoral Fellowship Program of CPSF(No.GZC20231545)the China Postdoctoral Science Foundation(Nos.2024T170557 and 2023M742224)+6 种基金the Shanghai Post-doctoral Excellence Program(No.2023440)the National Natural Science Foundation of China(Nos.52127801,52401101,and 22205012)the Shenzhen Basic Research Project(Nos.JCYJ20210324120001003,JCYJ20200109144608205)the Guangdong Basic and Applied Basic Research Foundation(Nos.2020A1515011301 and 2021A1515012246)the IER Foundation(Nos.IERF202201 andIERF202202),the City University of Hong Kong Donation Research(No.DON-RMG 9229021)the Hong Kong PDFS-RGC Postdoctoral Fellowship Scheme(Nos.PDFS2122–1S08 and CityU 9061014)the Hong Kong HMRF(Health and Medical Research Fund)(Nos.2120972 and CityU 9211320).
文摘The poor corrosion resistance of magnesium(Mg)and its alloys limits their application in various fields.Micro arc oxidation(MAO)coatings can improve the corrosion resistance,but the pore defects and low surface hardness make them susceptible to wear and accelerated corrosion during usage.In this study,a ZrO_(2)nanoparticles doped-MAO coating is prepared on the ZK61 Mg alloy by utilizing an MgF_(2)passivation layer to prevent ablation.The ZrO_(2)nanoparticles re-melt and precipitate due to local discharging,which produces evenly dispersed nanocrystals in the MAO coating.As a result,the hardness of the MAO coating with the appropriate ZrO_(2)concentration increases by over 10 times,while the wear rate decreases and corrosion resistance increases.With increasing ZrO_(2)concentrations,the corrosion potentials increase from−1.528 V of the bare ZK61 Mg alloy to−1.184 V,the corrosion current density decreases from 1.065×10^(–4)A cm^(–2)to 3.960×10^(–8)A cm^(–2),and the charge transfer resistance increases from 3.41×10^(2)Ωcm^(2)to 6.782×10^(5)Ωcm^(2).Immersion tests conducted in a salt solution for 28 d reveal minimal corrosion in contrast to severe corrosion on the untreated ZK61 Mg alloy.ZrO_(2)nanoparticles improve the corrosion resistance of MAO coatings by sealing pores and secondary strengthening of the corrosion product layer.
基金supported by Innovation Program for Quantum Science and Technology(No.2021ZD0302800)the National Natural Science Foundation of China(Nos.52373309 and 12004357)+2 种基金the National Key R&D Program of China(No.2023YFA1610100)the financial support from U.S.Department of Energy Office of Science-The Basic Energy Sciences program(DOE-BES)(No.DE-FG02-04ER46148)the financial support from the National Natural Science Foundation of China(No.12574210).
文摘Intrinsic topological superconductors have garnered significant attention for their potential to harbor novel quantum phenomena.However,the limited availability of suitable material systems has hindered progress in this field.Here,we present the synthesis and characterization of high-quality self-assembled SnS/TaS_(2)(SnTaS_(3))superlattice,which exhibits superconductivity alongside non-trivial band topology.Temperature-dependent magnetization susceptibility and electrical transport results confirm SnTaS_(3) as a type-Ⅱ superconductor with a critical transition temperature Tc of 3 K.Interestingly,this superconductivity can be turned off via an innovative solid proton gate technique,and a new superconducting state with a Tc of~2.3 K emerges when the gating voltage reaches-9.47 V.Heat capacity measurements reveal strong electronic correlations within this material,which is further supported by angle-resolved photoemission spectroscopy and first-principles calculations,underscoring the effect of topological flat bands and Van Hove singularity.Our research introduces a promising self-assembled material platform,adeptly positioned to delve into the quest for topological superconductors.
文摘Additive manufacturing(AM) of Ni-base superalloy components can lead to a significant reduction of weight in aerospace applications. AM of IN718 by selective laser melting results in a very fine dendritic microstructure with a high dislocation density due to the fast solidification process. The complex phase composition of this alloy, with three different types of precipitates and high residual stresses, necessitates adjustment of the conventional heat treatment for AM parts. To find an optimized heat treatment, the microstructures and mechanical properties of differently solution heat-treated samples were investigated by transmission and scanning electron microscopy, including electron backscatter diffraction, and compression tests. After a solution heat treatment(SHT), the Nb-rich Laves phase dissolves and the dislocation density is reduced, which eliminates the dendritic substructure. SHT at 930 or 954°C leads to the precipitation of the δ-phase, which reduces the volume fraction of the strengthening γ′-and γ′′-phases formed during the subsequent two stage aging treatment. With a higher SHT temperature of 1000°C, where no δ-phase is precipitated, higher γ′ and γ′′ volume fractions are achieved, which results in the optimum strength of all of the solution heat treated conditions.
基金This study was supported by the National Natural Science Foundation of China(51774109 and 51501039)the Key Research and Development Project of Jiangsu Province(BE2017148)+2 种基金the Postgraduate Research&Practice Innovation Program of Jiangsu Province of China(KYLX16_0701)the Fundamental Research Funds for the Central Universities(HHU2016B45314&2018B48414)Q.X.is grateful for the support from the China Scholarship Council and the W.M.Keck Center for Advanced Microscopy and Micr1oanalysis at University of Delaware.
文摘In the present work,AZ91 alloy was successfully processed by equal channel angular pressing(ECAP)for up to 16 passes and rolling(R)for multiple passes with a total reduction of 75%in addition to a combination method with ECAP plus rolling(ECAP+R).The effects of various processes(ECAP,R and ECAP+R)on microstructure evolution were analyzed and the influence of ECAP process on the rolling performance was examined.The result shows that ECAP contributed to a homogenous grain structure and formed a texture with higher Schmidt factors that was easy for rolling.A plate with smoother surface and reduced edge cracks was observed in the ECAP+R process than in the single R process.Although the microstructure of the alloy was similar after ECAP+R and R process,the sample of ECAP+R was more refined and had stronger second phase precipitation than the sample of R,which resulted in better rolling characteristics,along with the external surfaces.
基金the first Singapore-Germany Academic-Industry(2+2)international collaboration grant(Grant No.:A1890b0050)Agency for Science,Technology and Research(A^(*)STAR),under the RIE2020 Advanced Manufacturing and Engineering(AME)Programmatic Grant No.A1881b0061support of a scholarship from the A^(*)STAR Graduate Academy。
文摘Binder jet printing(BJP)is a state-of-the-art additive manufacturing technique for producing porous magnesium structures.Porous MgZn-Zr based BJP samples were assessed for corrosion performance in simulated body fluids by electrochemical and hydrogen evolution measurements.The corrosion rates of the BJP specimens were significantly higher than solid controls,even after accounting for their larger surface areas,suggesting that the BJP microstructure is detrimental to corrosion performance.X-ray computed tomography revealed nonuniform corrosion within the porous structure,with corrosion products forming on the pore walls.Impregnating the pores with hydroxyapatite or polymers greatly improved the corrosion resistance of the BJP samples.
基金financially supported by the National Natural Science Foundation of China (U2004210, 51974208, U2003130, 21875080, 52002297)the Outstanding Youth Foundation of Natural Science Foundation of Hubei Province (2020CFA099)+2 种基金the Special Project of Central Government for Local Science and Technology Development of Hubei Province (2019ZYYD024)the Innovation group of Natural Science Foundation of Hubei Province (2019CFA020)the City University of Hong Kong Strategic Research Grants (7005505)。
文摘Silicon (Si) is a promising anode material for next-generation high-energy lithium-ion batteries (LIBs) due to its high capacity.However,the large volumetric expansion,poor ion conductivity and unstable solid electrolyte interface (SEI) lead to rapid capacity fading and low rate performance.Herein,we report Si nitride (SiN) comprising stoichiometric Si_(3)N_(4) and Li-active anazotic SiN_(x) coated porous Si (p-Si@SiN)for high-performance anodes in LIBs.The ant-nest-like porous Si consisting of 3D interconnected Si nanoligaments and bicontinuous nanopores prevents pulverization and accommodates volume expansion during cycling.The Si_(3)N_(4) offers mechanically protective coating to endow highly structural integrity and inhibit superfluous formation of SEI.The fast ion conducting Li_(3)N generated in situ from lithiation of active SiN_(x) facilitates Li ion transport.Consequently,the p-Si@SiN anode has appealing electrochemical properties such as a high capacity of 2180 mAh g^(-1)at 0.5 A g^(-1) with 84%capacity retention after 200cycles and excellent rate capacity with discharge capacity of 721 mAh g^(-1) after 500 cycles at 5.0 A g^(-1).This work provides insights into the rational design of active/inactive nanocoating on Si-based anode materials for fast-charging and highly stable LIBs.
基金supported by a grant from the National Research Foundation of Korea(NRF)funded by the Korean government(MSIT)(NRF-2021R1A2B5B01002063)。
文摘Conventionally,Te has primarily been used to improve the machinability of steel and its alloys.In this work,Te was used to refine the grains of an oxide-dispersion-strengthened(ODS)steel produced by additive manufacturing(AM)with fixed processing parameters.Addition of Te to the raw powder produced an ODS steel with a fine-grained microstructure,in contrast to the ODS steel manufactured without Te.Moreover,the addition of Te resulted in superior yield strength and ultimate tensile strength,which was attributed to the combined effects of grain refinement and the finer nanoparticles(NPs)composed of Terich composite NPs and Cr-rich NPs.For the first time,the AM technique was used to obtain grain and nanoparticle sizes of~3.4μm and 6 nm,respectively,from the Te-added ODS steel.
文摘In the current study,a modified sol-gel route was used to produce undoped and Sm^(3+)doped(1 mol%,3 mol%and 5 mol%)ZnO nanoparticles(NPs).The study of opto-structural properties of Sm^(3+)doped NPs was carried out both experimentally and theoretically.Complete dissolution of Sm^(3+)ions into the ZnO lattice is obviously seen from X-ray diffraction(XRD)analysis.Morphological evolution with doping was studied using field emission scanning electron microscopy(FESEM)and transmission electron microscopy(TEM).X-ray photoelectron spectroscopy(XPS)was carried out to confirm the prese nce of Sm~(3+)on the doped NPs.Increasing dopant quantity results in a redshift of the NPs along with a reduction in bandgap with increasing abso rption in the visible range,and a minimum of 3.18 eV of optical bandgap for Zn_(0.97)Sm_(0.03)O is found.Photoluminescence spectroscopy reveals a drop in the recombination rate of electron-hole with increasing doping content till 3 mol%,followed by an increase of Zn_(0.95)Sm_(0.05)O.Photogenerated electron-hole pair recombination is revealed by the orange band in the luminescence spectra.Theoretical analysis was also carried out with density functional theory(DFT).This work also unfolds the fundamental understanding of the structural properties of the synthesized NPs to enhance photocatalytic activity successfully.Later,photocatalytic activity for the optimum composition,i.e.,3 mol%,was assessed experimentally.
基金funded by the Natural Science Foundation of Zhejiang Provincial (No. LQ17E020003)the National Natural Science Foundation of China (No. 51804092)
文摘Transition metal sulfides are emerging as promising electrode materials for energy storage and conversion.In this work,hierarchical FeS2/C nanospheres are synthesized through a controllable solvothermal method followed by the annealing process.Spherical FeS2 core is homogeneously coated by thin carbon shell.The hierarchical nanostructure and carbon coating can enhance electron transfer and accommodate the stress originated from the volume change as well as suppress the shuttle effect of polysulfide.Consequently,as the cathode material of lithium ion batteries(LIBs),the FeS2/C nanospheres exhibit high reversible capacity of 676 m Ahg^-1 and excellent cycling life with the capacity retention of 97.1%after100 cycles.In addition,even at the high current density of 1.8 C,a reversible capacity of 437 m Ahg^-1 is obtained for the FeS2/C nanospheres,demonstrating its great prospect for practical applications in highperformance LIBs.
基金JSPS KAKENHI for Scientific Research on Innovative Areas“Materials Science of a Mille-feuille Structure(Grant Numbers JP18H05475,JP18H05479)”the Open Funds of the State Key Laboratory of Rare Earth Resource Utilization(RERU2020012)+1 种基金“Nanotechnology Platform”of the MEXT,JapanGrant-in-Aid for JSPS Fellows(JP19F19775)。
文摘The effect of Gd content on the microstructure and tensile properties of as-cast Mg-Sm-Zn-Zr alloy has been systematically investigated.In the Mg-3Sm-0.5Zn-0.5Zr alloy, the intermetallic compounds with multiple morphologies are identified as Mg_(3)Sm phase. In addition to Mg_(3)RE phase, Mg_(5)RE phase originated from Gd addition is observed in Gd-modified alloys. It should be noted that the lattice parameters of all the observed intermetallic compounds are significantly reduced by Zn segregation. The segregation behavior of Zn in Mg_(3)Sm phase is inhibited to some extent by Gd addition due to the electronegativity difference between Sm/Gd and Zn elements. In addition, the increased Gd content effectively leads to much more accumulation of solute atoms in front of the liquid-solid interface during solidification, which can prominently promote nucleation in liquid region and then refine grains. The tensile yield stress of the present alloys is thus improved with increasing Gd addition. Finally, Gd-modified alloys exhibit significantly age-hardening effect, which can be mainly attributed to the high-volume fraction and high density nano-scale precipitates.
