Low-angle grain boundaries(LAGBs)are one of the solidification defects in single-crystal nickel-based superalloys and are detrimental to the mechanical properties.The formation of LAGBs is related to dendrite deformat...Low-angle grain boundaries(LAGBs)are one of the solidification defects in single-crystal nickel-based superalloys and are detrimental to the mechanical properties.The formation of LAGBs is related to dendrite deformation,while the mechanism has not been fully understood at the mesoscale.In this work,a model coupling dendrite growth,thermal-solutal-fluid flow,thermal stress and flow-induced dendrite deformation via cellular automaton-finite volume method and finite element method is developed to study the formation of LAGBs in single crystal superalloys.Results reveal that the bending of dendrites is primarily attributed to the thermal-solutal convection-induced dendrite deformation.The mechanical stress of dendrite deformation develops and stabilises as solidification proceeds.As the width of the mushy zone gets stable,stresses are built up and then dendritic elastoplastic bending occurs at some thin primary dendrites with the wider inter-dendritic space.There are three characteristic zones of stress distribution along the solidification direction:(i)no stress concentration in the fully solidified regions;(ii)stress developing in the primary dendrite bridging region,and(iii)stress decrease in the inter-dendritic uncontacted zone.The stresses reach maximum near the initial dendrite bridging position.The lower temperature gradients,the finer primary dendritic trunks and sudden reductions in local dendritic trunk radius jointly promote the elastoplastic deformation of the dendrites.Corresponding measures are suggested to reduce LAGBs.展开更多
Atomically dispersed metal site(ADMS)materials have emerged as a promising class of materials for electrocatalysis reactions in the field of energy conversion.Characterized by individual metal atoms dispersed on suita...Atomically dispersed metal site(ADMS)materials have emerged as a promising class of materials for electrocatalysis reactions in the field of energy conversion.Characterized by individual metal atoms dispersed on suitable supports,ADMS materials provide unique catalytic sites with highly tunable electronic structures.This review summarizes recent advancements in the field,with a focus on the critical roles of support materials,coordination environments,and the mechanisms underlying catalytic activity at the atomic level.First,commonly used density functional theory(DFT)simulations are reviewed,emphasizing their pivotal role in elucidating reaction mechanisms and predicting the behavior of ADMS in electrochemical reactions for hydrogen energy utilization.Then,advancements in ADMS for half-cell electrochemical reactions,including oxygen evolution reaction,hydrogen evolution reaction,and oxygen reduction reaction,as well as their applications in fuel cells and water splitting,are summarized.Finally,the challenges and future prospects of ADMS are discussed.This review underscores the transformative potential of ADMS in electrocatalysis,paving the way for innovative and sustainable energy conversion technologies.展开更多
The search for safer next-generation lithium-ion batteries(LIBs)has driven significant research on non-toxic,non-flammable solid electrolytes.However,their electrochemical performance often falls short.This work prese...The search for safer next-generation lithium-ion batteries(LIBs)has driven significant research on non-toxic,non-flammable solid electrolytes.However,their electrochemical performance often falls short.This work presents a simple,one-step photopolymerization process for synthesizing biphasic liquid–solid ionogel electrolytes using acrylic acid monomer and P_(111i4)FSI ionic liquid.We investigated the impact of lithium salt concentration and temperature on ion diffusion,particularly lithium-ion(Li^(+))mobility,within these ionogels.Pulsed-field gradient nuclear magnetic resonance(PFG-NMR)revealed enhanced Li^(+)diffusion in the acrylic acid(AA)-based ionogels compared to their non-confined ionic liquid counterparts.Remarkably,Li^(+)diffusion remained favorable in the ionogels regardless of salt concentration.These AA-based ionogels demonstrate very good ionic conductivity(>1 mS cm^(-1) at room temperature)and a wide electrochemical window(up to 5.3 V vs Li^(+)/Li^(0)).These findings suggest significant promise for AA-based ionogels as polymer solid electrolytes in future solid-state battery applications.展开更多
Understanding the structure-property relationship and the mechanisms by which catalysts promote polysulfide conversion is crucial for the rational design of room-temperature sodium-sulfur(RT Na-S)battery catalysts.Her...Understanding the structure-property relationship and the mechanisms by which catalysts promote polysulfide conversion is crucial for the rational design of room-temperature sodium-sulfur(RT Na-S)battery catalysts.Herein,we systematically investigate Fe-,Co-,and Ni-incorporated Mo_(2)C as catalysts for RT Na-S battery to elucidate the intrinsic correlation between the d band center of Mo in Mo_(2)C and its catalytic activity.Combining experimental and theoretical analysis revealed that Ni-substituted Mo_(2)C elevates the d band center while significantly reducing antibonding orbitals(π^(*))occupancy compared to Fe-substituted Mo_(2)C and Co-substituted Mo_(2)C counterparts.This electronic restruction enhances d-p hybridization at the Mo-S interface,which strengthens sodium polysulfides adsorption energy and enhances charge transfer,thereby steering sulfur redox pathways toward thermodynamically favorable configurations.Our findings elucidate the intricate interplay between the electronic structure and catalytic activity of Mo_(2)C,advancing a novel perspective for the rational design of RT Na-S battery catalysts through tailored modulation of antibonding orbital occupancy.展开更多
Layered vanadates are ideal energy storage materials due to their multielectron redox reactions and excellent cation storage capacity.However,their practical application still faces challenges,such as slow reaction ki...Layered vanadates are ideal energy storage materials due to their multielectron redox reactions and excellent cation storage capacity.However,their practical application still faces challenges,such as slow reaction kinetics and poor structural stability.In this study,we synthesized[Me_(2)NH_(2)]V_(3)O_(7)(MNVO),a layered vanadate with expended layer spacing and enhanced pH resistance,using a one-step simple hydrothermal gram-scale method.Experimental analyses and density functional theory(DFT)calculations revealed supportive ionic and hydrogen bonding interactions between the thin-layered[Me_(2)NH_(2)]+cation and[V_(3)O_(7)]-anion layers,clarifying the energy storage mechanism of the H^(+)/Zn^(2+)co-insertion.The synergistic effect of these bonds and oxygen vacancies increased the electronic conductivity and significantly reduced the diffusion energy barrier of the insertion ions,thereby improving the rate capability of the material.In an acidic electrolyte,aqueous zinc-ion batteries employing MNVO as the cathode exhibited a high specific capacity of 433 mAh g^(-1)at 0.1 A g^(-1).The prepared electrodes exhibited a maximum specific capacity of 237 mAh g^(-1)at 5 A g^(-1)and maintained a capacity retention of 83.5%after 10,000 cycles.This work introduces a novel approach for advancing layered cathodes,paving the way for their practical application in energy storage devices.展开更多
Bismuth-doped antimony tungstate(Bi-doped Sb_(2)WO_(6))microspheres were synthesized via a novel hydrothermal synthesis approach.These microspheres were then used as active layers in gas sensors for the detection of c...Bismuth-doped antimony tungstate(Bi-doped Sb_(2)WO_(6))microspheres were synthesized via a novel hydrothermal synthesis approach.These microspheres were then used as active layers in gas sensors for the detection of carbon dioxide(CO_(2)),a significant greenhouse gas and a critical parameter for evaluating air quality.The incorporation of bismuth significantly enhances the gas-sensing performance of the Sb_(2)WO_(6)microspheres,with the 4%Bidoped sensing active layer achieving a remarkable response value of 15 when exposed to 200 ppm of CO_(2),outperforming the undoped Sb_(2)WO_(6).Furthermore,the selectivity of the 4%Bi-Sb_(2)WO_(6)sensor toward CO_(2)gas was enhanced relative to the Sb_(2)WO_(6)sensor.The fundamental mechanisms of gas sensing and the factors contributing to the improved CO_(2)response of 4%Bi-Sb_(2)WO_(6)micro spheres were investigated using density functional theory.Bi-doped Sb_(2)WO_(6)materials exhibit significant advantages in gas-sensing applications,including improved conductivity,enhanced gas adsorption capacity,increased reaction rates,good chemical stability,excellent selectivity,and the ability to adjust electron density.These characteristics enable Bi-doped Sb_(2)WO_(6)to demonstrate higher sensitivity and rapid response capabilities in gas sensors,making it suitable for practical applications.展开更多
In this study,we simulated the thermal behavior of the mud-brick walls of a Nubian vault.We used EnergyPlus software for the simulation.The results obtained showed that the indoor temperature varies from 25.5℃ to 26....In this study,we simulated the thermal behavior of the mud-brick walls of a Nubian vault.We used EnergyPlus software for the simulation.The results obtained showed that the indoor temperature varies from 25.5℃ to 26.5℃ for the period of January 2018.It varies from 33.2℃ to 33.6℃ with an average value of 33.1℃ for the month of April 2018.For the period of July 2018,it varies from 30.3℃ to 32.2℃ with an average value of 31.2℃..Relative humidity for the period of July ranged from 62.3%to 73.5%,with an average value of 67.9%.The simulation enabled us to compare simulated and measured temperature and humidity values.We found that the level of thermal comfort in the Nubian vault is acceptable in both cool and hot periods.In view of these results,we can say that the Nubian vault is an architecture suited to our climate.The technical concept of the Nubian vault is adapted to the climatic conditions and traditional know-how of the Sahel.We also found that the use of raw earth,a locally available material,and the Nubian vault architectural process,contribute to thermal comfort and a reappropriation of local and adapted know-how.展开更多
To effectively enhance the catalytic activity of NiS,NiS particles confined into carbon fibers were prepared by electrostatic spinning followed pyrolyzation and NiS particles decorating was performed by further hydrot...To effectively enhance the catalytic activity of NiS,NiS particles confined into carbon fibers were prepared by electrostatic spinning followed pyrolyzation and NiS particles decorating was performed by further hydrothermal loading.The decorated NiS exhibits particle(NiS@PAN-NiS)and needle-like(NiS@PAN-NiS^(*))morphologies.After adding the catalysts into MgH_(2),the synthesized MgH_(2)-5 wt%NiS@PAN-NiS composite can absorb 2.6 wt%hydrogen at 353 K and release 5.0 wt%hydrogen within 1 h at 573 K.The initial hydrogen desorption temperature was reduced to 539 K.The activation energies for hydrogen absorption/desorption were greatly reduced to 66.76 and 89.95 kJ mol^(-1),respectively.The method of confining by electrospinning and particle decoration by hydrothermal loading reduce NiS particle agglomeration.The Mg_(2)Ni/Mg_(2)NiH_(4)hydrogen pump formed by reaction between NiS and MgH_(2)effectively enhanced hydrogen absorption and desorption kinetics.The formed MgS also improved the catalytic activity on the transformation of Mg and MgH_(2).Moreover,the carbon fibers should influence the contact between in situ formed MgS and Mg_(2)Ni,providing more catalytic sites and hydrogen diffusion pathways.The construction of NiS/carbon fibers confined NiS composite by carbon fibers derived from pyrolyzation as medium provides considerable way for designing NiS-based catalysts to enhance the hydrogen storage performances of MgH_(2).展开更多
The difference in the microstructure,texture in the stir zone(SZ)of the AZ31(Mg-3 Al-1 Zn,wt.%)alloy after friction stir welding(FSW)and subsequent annealing at 400℃for 1 h was characterized by scanning electron micr...The difference in the microstructure,texture in the stir zone(SZ)of the AZ31(Mg-3 Al-1 Zn,wt.%)alloy after friction stir welding(FSW)and subsequent annealing at 400℃for 1 h was characterized by scanning electron microscopy(SEM)with electron backscatter diffraction(EBSD)measurements at the surface and core regions.The findings indicate that FSW produced grain refinement where the mean grain size decreases from 19μm(base metal)to 5.1 and 3.5μm at the surface and core regions,respectively.The c-axis of the grains at the surface region was aligned with the normal direction(<0001>//ND)due to the additional strain of the tool shoulder.In contrast,the core region shows a typical shear texture,where the c-axis tends to be oriented parallel to the welding direction(<0001>//WD).The Vickers microhardness mapping across the SZ revealed that the core region was soften than the surface region due to the dynamic recrystallization and texture weakening.The microstructure of the SZ remains principally deformed after annealing treatment except for the development of massive Mg_(17)Al_(12)precipitates and the abnormal grain growth of a few grains with<11-20>//WD orientation at the upper side of the surface region.The c-axis of the grains at the surface region was tilted about 10°toward WD,while an inclined<0001>//WD orientation about 30°from WD was developed at the core region.Consequently,the distribution of microhardness values across the SZ was more heterogeneous than the FSW sample.The results were discussed in the light of grain boundary misorientation,dislocation density and the pinning effect of Mg_(17)Al_(12)precipitates.Additionally,Schmid factor analysis was used to examine the activation of the basal slip mode to characterize the associated mechanical response.展开更多
This study investigates the electrochemical behavior of molybdenum disulfide(MoS_(2))as an anode in Li-ion batteries,focusing on the extra capacity phenomenon.Employing advanced characterization methods such as in sit...This study investigates the electrochemical behavior of molybdenum disulfide(MoS_(2))as an anode in Li-ion batteries,focusing on the extra capacity phenomenon.Employing advanced characterization methods such as in situ and ex situ X-ray diffraction,Raman spectroscopy,X-ray photoelectron spectroscopy,and transmission electron microscopy,the research unravels the complex structural and chemical evolution of MoS_(2) throughout its cycling.A key discovery is the identification of a unique Li intercalation mechanism in MoS_(2),leading to the formation of reversible Li_(2)MoS_(2) phases that contribute to the extra capacity of the MoS_(2) electrode.Density function theory calculations suggest the potential for overlithiation in MoS_(2),predicting Li5MoS_(2) as the most energetically favorable phase within the lithiation–delithiation process.Additionally,the formation of a Li-rich phase on the surface of Li_(4)MoS_(2) is considered energetically advantageous.After the first discharge,the battery system engages in two main reactions.One involves operation as a Li-sulfur battery within the carbonate electrolyte,and the other is the reversible intercalation and deintercalation of Li in Li_(2)MoS_(2).The latter reaction contributes to the extra capacity of the battery.The incorporation of reduced graphene oxide as a conductive additive in MoS_(2) electrodes notably improves their rate capability and cycling stability.展开更多
采用熔盐顶部籽晶法从K 2 Mo 3 O 10-B 2 O 3助熔剂中生长出尺寸为20 mm的优质GdAl 3(BO 3)4(简称GAB)和Nd^3+激活的自变频激光晶体。确定了GAB晶体的透光波长范围、折射率和倍频系数随波长的变化,结果表明其在整个透光范围内均可实现...采用熔盐顶部籽晶法从K 2 Mo 3 O 10-B 2 O 3助熔剂中生长出尺寸为20 mm的优质GdAl 3(BO 3)4(简称GAB)和Nd^3+激活的自变频激光晶体。确定了GAB晶体的透光波长范围、折射率和倍频系数随波长的变化,结果表明其在整个透光范围内均可实现相位匹配。测定了Nd^3+∶GAB晶体在室温下的偏振吸收、荧光光谱和荧光寿命,进行了光谱计算,测试了晶体的自变频激光性能,实现了紫外-可见光-红外-中红外多波段激光输出。展开更多
基金sponsored by the National Natural Science Foundation of China(Grant Nos.52074182,52304406 and U23A20612)the Natural Science Foundation of Shanghai(Grant Nos.22ZR1430700 and 23TS1401900)+1 种基金the National Science and Technology Major Project(No.2017-VII-0008-0102)Neng Ren acknowledges the Startup Fund for Young Faculty at SJTU.
文摘Low-angle grain boundaries(LAGBs)are one of the solidification defects in single-crystal nickel-based superalloys and are detrimental to the mechanical properties.The formation of LAGBs is related to dendrite deformation,while the mechanism has not been fully understood at the mesoscale.In this work,a model coupling dendrite growth,thermal-solutal-fluid flow,thermal stress and flow-induced dendrite deformation via cellular automaton-finite volume method and finite element method is developed to study the formation of LAGBs in single crystal superalloys.Results reveal that the bending of dendrites is primarily attributed to the thermal-solutal convection-induced dendrite deformation.The mechanical stress of dendrite deformation develops and stabilises as solidification proceeds.As the width of the mushy zone gets stable,stresses are built up and then dendritic elastoplastic bending occurs at some thin primary dendrites with the wider inter-dendritic space.There are three characteristic zones of stress distribution along the solidification direction:(i)no stress concentration in the fully solidified regions;(ii)stress developing in the primary dendrite bridging region,and(iii)stress decrease in the inter-dendritic uncontacted zone.The stresses reach maximum near the initial dendrite bridging position.The lower temperature gradients,the finer primary dendritic trunks and sudden reductions in local dendritic trunk radius jointly promote the elastoplastic deformation of the dendrites.Corresponding measures are suggested to reduce LAGBs.
基金supported by the National Natural Science Foundation of China(22005072,21965006)Guizhou Provincial Key Technology R&D Program(Qian Ke He support(2023)General 122)+3 种基金Guiyang Guian Science and Technology Personnel Training Project([2024]2-13)Youth Science and Technology Talent Development Project from Guizhou Provincial Department of Education(KY[2022]163)Guizhou Provincial Science and Technology Foundation(KYJZ[2024]029)the ETS Marcelle-Gauvreau Engineering Research Chair program.
文摘Atomically dispersed metal site(ADMS)materials have emerged as a promising class of materials for electrocatalysis reactions in the field of energy conversion.Characterized by individual metal atoms dispersed on suitable supports,ADMS materials provide unique catalytic sites with highly tunable electronic structures.This review summarizes recent advancements in the field,with a focus on the critical roles of support materials,coordination environments,and the mechanisms underlying catalytic activity at the atomic level.First,commonly used density functional theory(DFT)simulations are reviewed,emphasizing their pivotal role in elucidating reaction mechanisms and predicting the behavior of ADMS in electrochemical reactions for hydrogen energy utilization.Then,advancements in ADMS for half-cell electrochemical reactions,including oxygen evolution reaction,hydrogen evolution reaction,and oxygen reduction reaction,as well as their applications in fuel cells and water splitting,are summarized.Finally,the challenges and future prospects of ADMS are discussed.This review underscores the transformative potential of ADMS in electrocatalysis,paving the way for innovative and sustainable energy conversion technologies.
基金funding from the European Union’s Horizon 2020 research and innovation program under the Marie Skłodowska-Curie Actions COFUND—Grant Agreement No:945357.
文摘The search for safer next-generation lithium-ion batteries(LIBs)has driven significant research on non-toxic,non-flammable solid electrolytes.However,their electrochemical performance often falls short.This work presents a simple,one-step photopolymerization process for synthesizing biphasic liquid–solid ionogel electrolytes using acrylic acid monomer and P_(111i4)FSI ionic liquid.We investigated the impact of lithium salt concentration and temperature on ion diffusion,particularly lithium-ion(Li^(+))mobility,within these ionogels.Pulsed-field gradient nuclear magnetic resonance(PFG-NMR)revealed enhanced Li^(+)diffusion in the acrylic acid(AA)-based ionogels compared to their non-confined ionic liquid counterparts.Remarkably,Li^(+)diffusion remained favorable in the ionogels regardless of salt concentration.These AA-based ionogels demonstrate very good ionic conductivity(>1 mS cm^(-1) at room temperature)and a wide electrochemical window(up to 5.3 V vs Li^(+)/Li^(0)).These findings suggest significant promise for AA-based ionogels as polymer solid electrolytes in future solid-state battery applications.
基金supported by the National Natural Science Foundation of China(No.52372224 and 52072299)the Major Project of Shaanxi Coal Joint Fund of Shaanxi.Provincial Science and Technology Department(No.2019JLZ-07)。
文摘Understanding the structure-property relationship and the mechanisms by which catalysts promote polysulfide conversion is crucial for the rational design of room-temperature sodium-sulfur(RT Na-S)battery catalysts.Herein,we systematically investigate Fe-,Co-,and Ni-incorporated Mo_(2)C as catalysts for RT Na-S battery to elucidate the intrinsic correlation between the d band center of Mo in Mo_(2)C and its catalytic activity.Combining experimental and theoretical analysis revealed that Ni-substituted Mo_(2)C elevates the d band center while significantly reducing antibonding orbitals(π^(*))occupancy compared to Fe-substituted Mo_(2)C and Co-substituted Mo_(2)C counterparts.This electronic restruction enhances d-p hybridization at the Mo-S interface,which strengthens sodium polysulfides adsorption energy and enhances charge transfer,thereby steering sulfur redox pathways toward thermodynamically favorable configurations.Our findings elucidate the intricate interplay between the electronic structure and catalytic activity of Mo_(2)C,advancing a novel perspective for the rational design of RT Na-S battery catalysts through tailored modulation of antibonding orbital occupancy.
基金Science Fund for Outstanding Young Scholars of Hunan Province,Grant/Award Number:2023JJ20064National Natural Science Foundation of China,Grant/Award Number:12004057+1 种基金Graduate Research and Innovation Foundation of Chongqing,Grant/Award Number:CYB23026Natural Science Foundation of Chongqing Municipality,Grant/Award Number:CSTB2022NSCQ-MSX1183。
文摘Layered vanadates are ideal energy storage materials due to their multielectron redox reactions and excellent cation storage capacity.However,their practical application still faces challenges,such as slow reaction kinetics and poor structural stability.In this study,we synthesized[Me_(2)NH_(2)]V_(3)O_(7)(MNVO),a layered vanadate with expended layer spacing and enhanced pH resistance,using a one-step simple hydrothermal gram-scale method.Experimental analyses and density functional theory(DFT)calculations revealed supportive ionic and hydrogen bonding interactions between the thin-layered[Me_(2)NH_(2)]+cation and[V_(3)O_(7)]-anion layers,clarifying the energy storage mechanism of the H^(+)/Zn^(2+)co-insertion.The synergistic effect of these bonds and oxygen vacancies increased the electronic conductivity and significantly reduced the diffusion energy barrier of the insertion ions,thereby improving the rate capability of the material.In an acidic electrolyte,aqueous zinc-ion batteries employing MNVO as the cathode exhibited a high specific capacity of 433 mAh g^(-1)at 0.1 A g^(-1).The prepared electrodes exhibited a maximum specific capacity of 237 mAh g^(-1)at 5 A g^(-1)and maintained a capacity retention of 83.5%after 10,000 cycles.This work introduces a novel approach for advancing layered cathodes,paving the way for their practical application in energy storage devices.
基金financially supported by the Outstanding Youth Foundation of Jiangsu Province of China(No.BK20211548)Yangzhou Science and Technology Plan Project(No.YZ2023246)+1 种基金China Scholarship Council(No.202308320445)the Postgraduate Research and Practice Innovation Program of Jiangsu Province of China(No.KYCX23_3551)
文摘Bismuth-doped antimony tungstate(Bi-doped Sb_(2)WO_(6))microspheres were synthesized via a novel hydrothermal synthesis approach.These microspheres were then used as active layers in gas sensors for the detection of carbon dioxide(CO_(2)),a significant greenhouse gas and a critical parameter for evaluating air quality.The incorporation of bismuth significantly enhances the gas-sensing performance of the Sb_(2)WO_(6)microspheres,with the 4%Bidoped sensing active layer achieving a remarkable response value of 15 when exposed to 200 ppm of CO_(2),outperforming the undoped Sb_(2)WO_(6).Furthermore,the selectivity of the 4%Bi-Sb_(2)WO_(6)sensor toward CO_(2)gas was enhanced relative to the Sb_(2)WO_(6)sensor.The fundamental mechanisms of gas sensing and the factors contributing to the improved CO_(2)response of 4%Bi-Sb_(2)WO_(6)micro spheres were investigated using density functional theory.Bi-doped Sb_(2)WO_(6)materials exhibit significant advantages in gas-sensing applications,including improved conductivity,enhanced gas adsorption capacity,increased reaction rates,good chemical stability,excellent selectivity,and the ability to adjust electron density.These characteristics enable Bi-doped Sb_(2)WO_(6)to demonstrate higher sensitivity and rapid response capabilities in gas sensors,making it suitable for practical applications.
文摘In this study,we simulated the thermal behavior of the mud-brick walls of a Nubian vault.We used EnergyPlus software for the simulation.The results obtained showed that the indoor temperature varies from 25.5℃ to 26.5℃ for the period of January 2018.It varies from 33.2℃ to 33.6℃ with an average value of 33.1℃ for the month of April 2018.For the period of July 2018,it varies from 30.3℃ to 32.2℃ with an average value of 31.2℃..Relative humidity for the period of July ranged from 62.3%to 73.5%,with an average value of 67.9%.The simulation enabled us to compare simulated and measured temperature and humidity values.We found that the level of thermal comfort in the Nubian vault is acceptable in both cool and hot periods.In view of these results,we can say that the Nubian vault is an architecture suited to our climate.The technical concept of the Nubian vault is adapted to the climatic conditions and traditional know-how of the Sahel.We also found that the use of raw earth,a locally available material,and the Nubian vault architectural process,contribute to thermal comfort and a reappropriation of local and adapted know-how.
基金financially supported by the National Natural Science Foundation of China(Nos.52101274 and 52472131)the Natural Science Foundation of Shandong Province(Nos.ZR2020QE011 and ZR2022ME089)+6 种基金Yantai Basic Research Project(No.2024JCYJ097)the Key Research and Development Projects of Shandong Province(No.2024TSGC0402)the Youth Top Talent Foundation of Yantai University(No.2219008)the Graduate Innovation Foundation of Yantai University(No.GIFYTU2240)the Natural Science Foundation of Qinghai Province for Distinguished Young Scholars(No.2025-ZJ-966J)the Talent Youth Project of Chinese Academy of Sciences(No.E410GC03)the CollegeStudent Innovation and Entrepreneurship Training Program Project(No.202311066088)
文摘To effectively enhance the catalytic activity of NiS,NiS particles confined into carbon fibers were prepared by electrostatic spinning followed pyrolyzation and NiS particles decorating was performed by further hydrothermal loading.The decorated NiS exhibits particle(NiS@PAN-NiS)and needle-like(NiS@PAN-NiS^(*))morphologies.After adding the catalysts into MgH_(2),the synthesized MgH_(2)-5 wt%NiS@PAN-NiS composite can absorb 2.6 wt%hydrogen at 353 K and release 5.0 wt%hydrogen within 1 h at 573 K.The initial hydrogen desorption temperature was reduced to 539 K.The activation energies for hydrogen absorption/desorption were greatly reduced to 66.76 and 89.95 kJ mol^(-1),respectively.The method of confining by electrospinning and particle decoration by hydrothermal loading reduce NiS particle agglomeration.The Mg_(2)Ni/Mg_(2)NiH_(4)hydrogen pump formed by reaction between NiS and MgH_(2)effectively enhanced hydrogen absorption and desorption kinetics.The formed MgS also improved the catalytic activity on the transformation of Mg and MgH_(2).Moreover,the carbon fibers should influence the contact between in situ formed MgS and Mg_(2)Ni,providing more catalytic sites and hydrogen diffusion pathways.The construction of NiS/carbon fibers confined NiS composite by carbon fibers derived from pyrolyzation as medium provides considerable way for designing NiS-based catalysts to enhance the hydrogen storage performances of MgH_(2).
基金supported by the PHC-Tassili program No.24MDU114。
文摘The difference in the microstructure,texture in the stir zone(SZ)of the AZ31(Mg-3 Al-1 Zn,wt.%)alloy after friction stir welding(FSW)and subsequent annealing at 400℃for 1 h was characterized by scanning electron microscopy(SEM)with electron backscatter diffraction(EBSD)measurements at the surface and core regions.The findings indicate that FSW produced grain refinement where the mean grain size decreases from 19μm(base metal)to 5.1 and 3.5μm at the surface and core regions,respectively.The c-axis of the grains at the surface region was aligned with the normal direction(<0001>//ND)due to the additional strain of the tool shoulder.In contrast,the core region shows a typical shear texture,where the c-axis tends to be oriented parallel to the welding direction(<0001>//WD).The Vickers microhardness mapping across the SZ revealed that the core region was soften than the surface region due to the dynamic recrystallization and texture weakening.The microstructure of the SZ remains principally deformed after annealing treatment except for the development of massive Mg_(17)Al_(12)precipitates and the abnormal grain growth of a few grains with<11-20>//WD orientation at the upper side of the surface region.The c-axis of the grains at the surface region was tilted about 10°toward WD,while an inclined<0001>//WD orientation about 30°from WD was developed at the core region.Consequently,the distribution of microhardness values across the SZ was more heterogeneous than the FSW sample.The results were discussed in the light of grain boundary misorientation,dislocation density and the pinning effect of Mg_(17)Al_(12)precipitates.Additionally,Schmid factor analysis was used to examine the activation of the basal slip mode to characterize the associated mechanical response.
基金the financial support from the Science, Technology, and Innovation Funding Authority (STIFA, STDF previously) through project number 42691 entitled “Microstructure-Based, Multi-Physics Simulation and Optimization to Improve Battery Performance”supported by the U.S. DOE (Department of Energy), Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357supported by the U.S. DOE Vehicle Technologies office, under contract number DE-AC02-06CH11357
文摘This study investigates the electrochemical behavior of molybdenum disulfide(MoS_(2))as an anode in Li-ion batteries,focusing on the extra capacity phenomenon.Employing advanced characterization methods such as in situ and ex situ X-ray diffraction,Raman spectroscopy,X-ray photoelectron spectroscopy,and transmission electron microscopy,the research unravels the complex structural and chemical evolution of MoS_(2) throughout its cycling.A key discovery is the identification of a unique Li intercalation mechanism in MoS_(2),leading to the formation of reversible Li_(2)MoS_(2) phases that contribute to the extra capacity of the MoS_(2) electrode.Density function theory calculations suggest the potential for overlithiation in MoS_(2),predicting Li5MoS_(2) as the most energetically favorable phase within the lithiation–delithiation process.Additionally,the formation of a Li-rich phase on the surface of Li_(4)MoS_(2) is considered energetically advantageous.After the first discharge,the battery system engages in two main reactions.One involves operation as a Li-sulfur battery within the carbonate electrolyte,and the other is the reversible intercalation and deintercalation of Li in Li_(2)MoS_(2).The latter reaction contributes to the extra capacity of the battery.The incorporation of reduced graphene oxide as a conductive additive in MoS_(2) electrodes notably improves their rate capability and cycling stability.
文摘采用熔盐顶部籽晶法从K 2 Mo 3 O 10-B 2 O 3助熔剂中生长出尺寸为20 mm的优质GdAl 3(BO 3)4(简称GAB)和Nd^3+激活的自变频激光晶体。确定了GAB晶体的透光波长范围、折射率和倍频系数随波长的变化,结果表明其在整个透光范围内均可实现相位匹配。测定了Nd^3+∶GAB晶体在室温下的偏振吸收、荧光光谱和荧光寿命,进行了光谱计算,测试了晶体的自变频激光性能,实现了紫外-可见光-红外-中红外多波段激光输出。
