Compositing a secondary phase in Ag_(2)Se can usually tune the electron and phonon scattering to improve the thermoelectric performance.However,the intrinsically high carrier concentration still limits the performance...Compositing a secondary phase in Ag_(2)Se can usually tune the electron and phonon scattering to improve the thermoelectric performance.However,the intrinsically high carrier concentration still limits the performance optimization.Here,we employ a modulation decoration strategy to simultaneously achieve submicron-scale constituents and compositional modification for synergistic optimization of thermoelectric properties.Amorphous nano Sb_(2)S_(3) has been decorated on the surface of Ag_(2)Se powders,and S was added into the Ag_(2)Se matrix through an ion exchange reaction accompanied by the formation of a crystal/amorphous mixed secondary phase of Sb_(2)(S,Se)_(3).The S doping reduced the excessive intrinsic carrier concentration,leading to modified electrical transport properties and significantly reduced electrical thermal conductivity.On the other hand,introducing the S dopants and the crystal/amorphous interfaces into the Ag_(2)Se matrix could increase the lattice anharmonicity,further contributing to the reduced thermal conductivity.Consequently,the Ag_(2)Se-0.4%Sb_(2)S_(3) sample obtains a high average zT value of>1 in the temperature range of 300–390 K.In addition,the maximum cooling temperature difference of over 85 K can be predicted in an Ag_(2)Se/Ag_(2)Se-0.4%Sb_(2)S_(3) segregated module at the hot side temperature of 350 K.展开更多
Electronic-state modulation strategy offers great potential in designing RuO_(2)-based bifunctionalelectrocatalysts for rechargeable Zn-air batteries(ZABs).Various three-dimensional(3D)transition metal oxides are atte...Electronic-state modulation strategy offers great potential in designing RuO_(2)-based bifunctionalelectrocatalysts for rechargeable Zn-air batteries(ZABs).Various three-dimensional(3D)transition metal oxides are attempted to couple with RuO_(2)for constructing an appropriate Ru—O—M interface.This work aims to construct Co_(3)O_(4)-RuO_(2)heterostructures on carbon sheets(Co_(3)O_(4)/RuO_(2)/NCNS)for boosting electronic transfer and regulation.Experiments and theoretical calculations identify the electronic transfer from Co_(3)O_(4)to RuO_(2)that modulates the electronic structure of metal surfaces/interfaces.Specifically,it leads to the increase in Co3+content,electron-rich state at RuO_(2)surface and electronic accumulation at interfaces.Moreover,this electronic-state modulation optimizes the d-band center in Co_(3)O_(4)/RuO_(2)that lowers the reaction barriers and endows interfaces as the biggest contributor to oxygen reduction reaction(ORR)and oxygen evolution reaction(OER)performance,The Co_(3)O_(4)/RuO_(2)/NCNS shows a quite low potential difference of 0.62 V and remarkable durability for ORR/OER.Co_(3)O_(4)/RuO_(2)/NCNS-assembled ZABs exhibit an excellent specific capacity of 818.3 mA h g^(-1)and a superior lifespan over 750 h.展开更多
It is desirable to fabricate materials with adjustable physical properties that can be used in different industrial applications.Since the property of a material is highly dependent on its inner structure,the understa...It is desirable to fabricate materials with adjustable physical properties that can be used in different industrial applications.Since the property of a material is highly dependent on its inner structure,the understanding of structure–property correlation is critical to the design of engineering materials.3D printing appears as a mature method to effectively produce micro-structured materials.In this work,we created different stainless-steel microstructures by adjusting the speed of 3D printing and studied the relationship between thermal property and printing speed.Our microstructure study demonstrates that highly porous structures appear at higher speeds,and there is a nearly linear relationship between porosity and printing speed.The thermal conductivity of samples fabricated by different printing speeds is characterized.Then,the correlation between porosity,thermal conductivity,and scanning speed is established.Based on this correlation,the thermal conductivity of a sample can be predicted from its printing speed.We fabricated a new sample at a different speed,and the thermal conductivity measurement agrees well with the value predicted from the correlation.To explore thermal transport physics,the effects of pore structure and temperature on the thermal performance of the printed block are also studied.Our work demonstrates that the combination of the 3D printing technique and the printing speed control can regulate the thermophysical properties of materials.展开更多
As a new three-dimensional(3-D)modulation,Polarization Quadrature Amplitude Modulation(PQAM) can be regarded as the combination of Pulse amplitude modulation(PAM) and Quadrature Amplitude Modulation(QAM) Modulation.It...As a new three-dimensional(3-D)modulation,Polarization Quadrature Amplitude Modulation(PQAM) can be regarded as the combination of Pulse amplitude modulation(PAM) and Quadrature Amplitude Modulation(QAM) Modulation.It can better improve the digital communication efficiency and reduce the Symbol error rate(SER) of the system than one-dimensional or two-dimensional modulation scheme.How to design a feasible constellation is the most concerned problem of PQAM currently.This paper first studies the relationship between the SER theoretical value of PQAM and the distribution of M and N,proposes a new M,N allocation scheme.Secondly,a new and straightforward design method of constructing higher-level 3-D signal constellations,which can be matched with the PQAM,and the constellation can divided into three different structures according to the ary for PQAM.Finally,the simulation results show that:in PQAM system,the modulation scheme and the constellation mapping scheme are proposed in this paper which can effectively reduce the system SER and improve the anti-noise performance of the system.展开更多
Poly(3-hexylthiophene)(P3HT)is one of the most promising hole-transporting materials in the pursuit of efficient and stable perovskite solar cells due to its outstanding stability and low cost.However,the intrinsic lo...Poly(3-hexylthiophene)(P3HT)is one of the most promising hole-transporting materials in the pursuit of efficient and stable perovskite solar cells due to its outstanding stability and low cost.However,the intrinsic low carrier density of P3 HT and poor contact between the P3HT/perovskite interface always lead to a low performance of the solar cell,while conventional chemical doping always makes the films unstable and limits the scalability.In this work,for the first time,we simultaneously enhanced the hole transporting properties of P3HT film and the interface of perovskite by doping it with a judiciously designed oxidized small molecule organic semiconductor.The organic salt not only can promote the lamellar crystallinity of P3HT to obtain better charge transport properties,but also reduce the defects of perovskite.As a result,we achieved champion efficiencies of 23.0%for small-area solar cells and 18.8%for larger-area modules(48.0 cm^(2)).This efficiency is the highest value for P3HT-based perovskite modules.Moreover,the solar cells show excellent operational stability,retaining over 95%of their initial efficiencies after1200 h of continuous operation.展开更多
It is necessary to investigate the characteristics of Mesenchymal stem cells(MSCs)derived exosomes,and especially their application in tissue regeneration.Previous studies have shown that inflammatory stimulation enha...It is necessary to investigate the characteristics of Mesenchymal stem cells(MSCs)derived exosomes,and especially their application in tissue regeneration.Previous studies have shown that inflammatory stimulation enhanced the secretion of MSC-derived exosomes with stronger anti-inflammatory protein,cytokine profiles,and functional RNA via altering COX2/PGE2 pathway.Recently,accumulating evidence has also revealed that biophysical cues(especially biomechanical cues)in cell microenvironment have significant effects not only on cells but also on their exosomes.It has been reported that applying bi-axial strain to MSCs induces formation of a stiffer cytoskeleton through mTORC2 signaling,which biases against adipogenic differentiation and toward osteoblastogenesis.At the same time,For example,dimensionality,composition and stiffness of the extracellular matrix(ECM)has been proved to affect the size and composition of exosomes secreted by cancer cells.However,the effects of biomechanical cues in the three-dimensional(3D)microenvironment on stem cell-derived exosomes remains to be unveiled.Therefore,it is important to understand the roles of 3D cell mechanical microenvironment in regulating the characteristics of stem cell-derived exosomes and develop more efficient approaches to enhance their functions.This study aimed to explore the changes in characteristics of exosomes secreted by MSCs in periodontium in response to the matrix strain in 3D.Periodontal ligament stem cells(PDLSCs)were cultured in a 3D strain microenvironment engineered with microscale magnetically stretched collagen hydrogels.The morphology,particle distribution,marker protein expression of PDLSC-derived exosomes were analyzed.Then the pro-osteogenic property of exosomes was evaluated by assessing cell viability,proliferation,migration and osteogenic differentiation of target cells,for instance human bone marrow mesenchymal stem cells(hBMSCs).Detailed characterizations revealed that PDLSC-derived exosomes in the 3D strain mi-croenvironment were with similar morphology,particle distribution and surface markers.Notably,Exosomes secreted by PDLSCs in strain microenvironment were more endocytosed by hBMSCs and were more potent in improving proliferation and migration of hBMSCs,comparing with PDLSCs in non-strain environment.Alizarin red staining and molecular biology experiments confirmed that treatment of exosomes secreted by PDLSCs under mechanical stimulation led to a significant increase in osteogenic differentiation of hBMSCs in vitro.Meanwhile,in vivo study also indicated that PDLSC-derived exosomes obtained from the 3D strain microenvironment could obviously promote new bone formation.Our findings revealed that mechanical cues profoundly affected the characteristics of PDLSC-derived exosomes,especially for their bio-activity,providing a foundation for using the 3D mechanical microenvironment to enhance the osteo-inductive functions of stem cell-derived exosomes in cell-free therapy for bone regeneration.展开更多
Two-dimensional(2D)metal organic frameworks(MOFs)are emerging as low-cost oxygen evolution reaction(OER)electrocatalysts,however,suffering aggregation and poor operation stability.Herein,ultrafine Fe_(3)O_(4) nanopart...Two-dimensional(2D)metal organic frameworks(MOFs)are emerging as low-cost oxygen evolution reaction(OER)electrocatalysts,however,suffering aggregation and poor operation stability.Herein,ultrafine Fe_(3)O_(4) nanoparticles(diameter:6±2 nm)are homogeneously immobilized on 2D Ni based MOFs(Ni-BDC,thickness:5±1 nm)to improve the OER stability.Electronic structure modulation for enhanced catalytic activity is studied via adjusting the amount of Fe_(3)O_(4) nanoparticles on Ni-BDC.The optimal Fe_(3)O_(4)/Ni-BDC achieves the best OER performance with an overpotential of 295 mV at 10 mA cm^(-2),a Tafel slope of 47.8 mV dec^(-1) and a considerable catalytic durability of more than 40 h(less than 5 h for Ni-BDC alone).DFT calculations confirm that the active sites for Fe_(3)O_(4)/Ni-BDC are mainly contributed by Fe species with a higher oxidation state,and the potential-determining step(PDS)is the formation of the adsorbed O*species,which are facilitated in the composite.展开更多
Sodium-based halide solid electrolytes offer excellent electrochemical stability and favorable interfacial compatibility,yet their low ionic conductivity at room temperature limits their application in all-solidstate ...Sodium-based halide solid electrolytes offer excellent electrochemical stability and favorable interfacial compatibility,yet their low ionic conductivity at room temperature limits their application in all-solidstate Na-ion batteries(ASSNIBs),Here,we develop a series of LaCl_(3)-based sodium superionic conductors engineered through cation vacancy-concentration modulation,which facilitates the formation of a threedimensional Na+transport network and increases the density of ion-hopping sites.The optimized Na_(0.4)Ta_(0.236)La_(0.472)Cl_(3)(NTLC)electrolyte achieves a Na+conductivity of 1.38×10^(-3) S/cm at 30℃,with a reduced activation energy of 0.26 eV.It also exhibits excellent mechanical deformation and moderate high-voltage stability,resulting in enhanced interfacial compatibility.When paired directly with an uncoated NaCrO_(2) cathode,the NTLC catholyte enables ASSNIBs to cycle stably over 300 cycles with89.7%capacity retention at 0.3 C and room temperature.This work underscores the potential of vacancy-rich LaCl_(3)-based sodium superionic conductors for advancing high-performance ASSNIBs.展开更多
The influences of two kinds of casting modules of metal casting （MC） and expandable pattern casting （EPC） on the corrosion behavior of Mg-11Gd-3Y alloy were studied by electrochemical measurements, scanning electr...The influences of two kinds of casting modules of metal casting （MC） and expandable pattern casting （EPC） on the corrosion behavior of Mg-11Gd-3Y alloy were studied by electrochemical measurements, scanning electron microscopy （SEM） observation, X-ray diffractometry （XRD） and X-ray photoelectron spectroscopy （XPS） analysis. It is found that the quantity of the Mg 24 （Gd, Y） 5 phase in MC is more than that in EPC due to the cooling rate. There is more alloying element dissolved in the matrix compared with MC. For EPC, the galvanic corrosion effect between the matrix and the Mg 24 （Gd, Y） 5 phase decreases and the corrosion resistance increases compared with the MC. The chief corrosion mode for Mg-11Gd-3Y alloy is pitting corrosion because most of the alloying elements are transformed into intermetallic phases. The average corrosion rate of the MC alloy in the immersion test is five times higher than that of EPC alloy and yttrium is present in the product film, which will provide increased protection for Mg-11Gd-3Y alloy. The electrochemical measurements and immersion test show that the EPC process increases the corrosion resistance compared with the MC Mg-11Gd-3Y alloy.展开更多
A simple and fast route for the synthesis of metal-organic framework（MOF） particles was presented.Cu 3（BTC） 2（HKUST-1,BTC=1,3,5-benzenetricarboxylate）,one of the most well-known MOFs,was synthesized at room temp...A simple and fast route for the synthesis of metal-organic framework（MOF） particles was presented.Cu 3（BTC） 2（HKUST-1,BTC=1,3,5-benzenetricarboxylate）,one of the most well-known MOFs,was synthesized at room temperature via coordination modulation method.By adding different modulators（monocarboxylic acids） into the reaction system,the morphologies of HKUST-1 crystals were tuned from nano spheres to micro octahedrons at room temperature without any complex equipment.X-Ray diffractions and gas sorption measurements revealed highly crystalline particles with large Brunauer-Emmett-Teller（BET） surface areas（1116―1273 m^ 2 /g） and total pore volumes（0.62―0.73 cm^ 3 /g）.The significantly small particle sizes and high capacity of gas sorption are considered advantageous for envisaged application in practical industrial process.展开更多
Semiconducting piezoelectricα-In_(2)Se_(3) and 3R MoS_(2) have attracted tremendous attention due to their unique electronic properties.Artificial van der Waals(vdWs)hetero-structures constructed withα-In_(2)Se_(3)a...Semiconducting piezoelectricα-In_(2)Se_(3) and 3R MoS_(2) have attracted tremendous attention due to their unique electronic properties.Artificial van der Waals(vdWs)hetero-structures constructed withα-In_(2)Se_(3)and 3R MoS_(2)flakes have shown promising applications in optoelectronics and photocatal-ysis.Here,we present the first flexibleα-In_(2)Se_(3)/3R MoS_(2)vdWs p-n heterojunction devices for photodetection from the visible to near infrared region.These heterojunction devices exhibit an ultrahigh photoresponsivity of 2.9×10^(3)A W^(−1) and a substantial specific detectivity of 6.2×10^(10) Jones under a compressive strain of−0.26%.The photocurrent can be increased by 64%under a tensile strain of+0.35%,due to the heterojunction energy band modulation by piezoelectric polarization charges at the hetero-junction interface.This work demonstrates a feasible approach to enhancement of α-In_(2)Se_(3)/3R MoS_(2) photoelectric response through an appropriate mechanical stimulus.展开更多
基金financially supported by the National Natural Science Foundation of China(Nos.52472105,52272246,and 12074015)the Sichuan Science and Technology Program(Nos.2024YFHZ0309 and 2023NSFSC1596)the State Key Laboratory for Mechanical Behavior of Materials(No.20232509).
文摘Compositing a secondary phase in Ag_(2)Se can usually tune the electron and phonon scattering to improve the thermoelectric performance.However,the intrinsically high carrier concentration still limits the performance optimization.Here,we employ a modulation decoration strategy to simultaneously achieve submicron-scale constituents and compositional modification for synergistic optimization of thermoelectric properties.Amorphous nano Sb_(2)S_(3) has been decorated on the surface of Ag_(2)Se powders,and S was added into the Ag_(2)Se matrix through an ion exchange reaction accompanied by the formation of a crystal/amorphous mixed secondary phase of Sb_(2)(S,Se)_(3).The S doping reduced the excessive intrinsic carrier concentration,leading to modified electrical transport properties and significantly reduced electrical thermal conductivity.On the other hand,introducing the S dopants and the crystal/amorphous interfaces into the Ag_(2)Se matrix could increase the lattice anharmonicity,further contributing to the reduced thermal conductivity.Consequently,the Ag_(2)Se-0.4%Sb_(2)S_(3) sample obtains a high average zT value of>1 in the temperature range of 300–390 K.In addition,the maximum cooling temperature difference of over 85 K can be predicted in an Ag_(2)Se/Ag_(2)Se-0.4%Sb_(2)S_(3) segregated module at the hot side temperature of 350 K.
基金supported by the National Natural Science Foundation of China(52273264)the Outstanding Youth Fund of Heilongjiang Province(JQ 2020B002).
文摘Electronic-state modulation strategy offers great potential in designing RuO_(2)-based bifunctionalelectrocatalysts for rechargeable Zn-air batteries(ZABs).Various three-dimensional(3D)transition metal oxides are attempted to couple with RuO_(2)for constructing an appropriate Ru—O—M interface.This work aims to construct Co_(3)O_(4)-RuO_(2)heterostructures on carbon sheets(Co_(3)O_(4)/RuO_(2)/NCNS)for boosting electronic transfer and regulation.Experiments and theoretical calculations identify the electronic transfer from Co_(3)O_(4)to RuO_(2)that modulates the electronic structure of metal surfaces/interfaces.Specifically,it leads to the increase in Co3+content,electron-rich state at RuO_(2)surface and electronic accumulation at interfaces.Moreover,this electronic-state modulation optimizes the d-band center in Co_(3)O_(4)/RuO_(2)that lowers the reaction barriers and endows interfaces as the biggest contributor to oxygen reduction reaction(ORR)and oxygen evolution reaction(OER)performance,The Co_(3)O_(4)/RuO_(2)/NCNS shows a quite low potential difference of 0.62 V and remarkable durability for ORR/OER.Co_(3)O_(4)/RuO_(2)/NCNS-assembled ZABs exhibit an excellent specific capacity of 818.3 mA h g^(-1)and a superior lifespan over 750 h.
基金supported by the National Key R&D Program of China(Nos.2018YFB1106100,2019YFE0119900)the National Natural Science Foundation of China(No.52076156)the Fundamental Research Funds for the Central Universities(No.2042020kf0194)。
文摘It is desirable to fabricate materials with adjustable physical properties that can be used in different industrial applications.Since the property of a material is highly dependent on its inner structure,the understanding of structure–property correlation is critical to the design of engineering materials.3D printing appears as a mature method to effectively produce micro-structured materials.In this work,we created different stainless-steel microstructures by adjusting the speed of 3D printing and studied the relationship between thermal property and printing speed.Our microstructure study demonstrates that highly porous structures appear at higher speeds,and there is a nearly linear relationship between porosity and printing speed.The thermal conductivity of samples fabricated by different printing speeds is characterized.Then,the correlation between porosity,thermal conductivity,and scanning speed is established.Based on this correlation,the thermal conductivity of a sample can be predicted from its printing speed.We fabricated a new sample at a different speed,and the thermal conductivity measurement agrees well with the value predicted from the correlation.To explore thermal transport physics,the effects of pore structure and temperature on the thermal performance of the printed block are also studied.Our work demonstrates that the combination of the 3D printing technique and the printing speed control can regulate the thermophysical properties of materials.
基金supported in part by the National Natural Science Foundation of China (61561039, 61271177, and 61461044)
文摘As a new three-dimensional(3-D)modulation,Polarization Quadrature Amplitude Modulation(PQAM) can be regarded as the combination of Pulse amplitude modulation(PAM) and Quadrature Amplitude Modulation(QAM) Modulation.It can better improve the digital communication efficiency and reduce the Symbol error rate(SER) of the system than one-dimensional or two-dimensional modulation scheme.How to design a feasible constellation is the most concerned problem of PQAM currently.This paper first studies the relationship between the SER theoretical value of PQAM and the distribution of M and N,proposes a new M,N allocation scheme.Secondly,a new and straightforward design method of constructing higher-level 3-D signal constellations,which can be matched with the PQAM,and the constellation can divided into three different structures according to the ary for PQAM.Finally,the simulation results show that:in PQAM system,the modulation scheme and the constellation mapping scheme are proposed in this paper which can effectively reduce the system SER and improve the anti-noise performance of the system.
基金financially supported by the National Natural Science Foundation of China(52472248 and 22075221)the Key Research and Development Project of Shanxi Province(202202060301003 and 202202060301015)the Innovation Program of Wuhan-Shuguang Project(2023010201020367)。
文摘Poly(3-hexylthiophene)(P3HT)is one of the most promising hole-transporting materials in the pursuit of efficient and stable perovskite solar cells due to its outstanding stability and low cost.However,the intrinsic low carrier density of P3 HT and poor contact between the P3HT/perovskite interface always lead to a low performance of the solar cell,while conventional chemical doping always makes the films unstable and limits the scalability.In this work,for the first time,we simultaneously enhanced the hole transporting properties of P3HT film and the interface of perovskite by doping it with a judiciously designed oxidized small molecule organic semiconductor.The organic salt not only can promote the lamellar crystallinity of P3HT to obtain better charge transport properties,but also reduce the defects of perovskite.As a result,we achieved champion efficiencies of 23.0%for small-area solar cells and 18.8%for larger-area modules(48.0 cm^(2)).This efficiency is the highest value for P3HT-based perovskite modules.Moreover,the solar cells show excellent operational stability,retaining over 95%of their initial efficiencies after1200 h of continuous operation.
基金financially supported by the Young Elite Scientist Sponsorship Program by CAST ( 2018QNRC001)the China Postdoctoral Science Foundation ( 2018M631172)
文摘It is necessary to investigate the characteristics of Mesenchymal stem cells(MSCs)derived exosomes,and especially their application in tissue regeneration.Previous studies have shown that inflammatory stimulation enhanced the secretion of MSC-derived exosomes with stronger anti-inflammatory protein,cytokine profiles,and functional RNA via altering COX2/PGE2 pathway.Recently,accumulating evidence has also revealed that biophysical cues(especially biomechanical cues)in cell microenvironment have significant effects not only on cells but also on their exosomes.It has been reported that applying bi-axial strain to MSCs induces formation of a stiffer cytoskeleton through mTORC2 signaling,which biases against adipogenic differentiation and toward osteoblastogenesis.At the same time,For example,dimensionality,composition and stiffness of the extracellular matrix(ECM)has been proved to affect the size and composition of exosomes secreted by cancer cells.However,the effects of biomechanical cues in the three-dimensional(3D)microenvironment on stem cell-derived exosomes remains to be unveiled.Therefore,it is important to understand the roles of 3D cell mechanical microenvironment in regulating the characteristics of stem cell-derived exosomes and develop more efficient approaches to enhance their functions.This study aimed to explore the changes in characteristics of exosomes secreted by MSCs in periodontium in response to the matrix strain in 3D.Periodontal ligament stem cells(PDLSCs)were cultured in a 3D strain microenvironment engineered with microscale magnetically stretched collagen hydrogels.The morphology,particle distribution,marker protein expression of PDLSC-derived exosomes were analyzed.Then the pro-osteogenic property of exosomes was evaluated by assessing cell viability,proliferation,migration and osteogenic differentiation of target cells,for instance human bone marrow mesenchymal stem cells(hBMSCs).Detailed characterizations revealed that PDLSC-derived exosomes in the 3D strain mi-croenvironment were with similar morphology,particle distribution and surface markers.Notably,Exosomes secreted by PDLSCs in strain microenvironment were more endocytosed by hBMSCs and were more potent in improving proliferation and migration of hBMSCs,comparing with PDLSCs in non-strain environment.Alizarin red staining and molecular biology experiments confirmed that treatment of exosomes secreted by PDLSCs under mechanical stimulation led to a significant increase in osteogenic differentiation of hBMSCs in vitro.Meanwhile,in vivo study also indicated that PDLSC-derived exosomes obtained from the 3D strain microenvironment could obviously promote new bone formation.Our findings revealed that mechanical cues profoundly affected the characteristics of PDLSC-derived exosomes,especially for their bio-activity,providing a foundation for using the 3D mechanical microenvironment to enhance the osteo-inductive functions of stem cell-derived exosomes in cell-free therapy for bone regeneration.
基金support from the Chinese Scholarship Council(201706220080)for W.H.the Natural Science Foundation of Hunan Province(2019JJ50526)for C.P.+1 种基金The Danish Council for Independent Research for the YDUN project(DFF 4093-00297)to J.Z.Villum Experiment(grant No.35844)for X.X.
文摘Two-dimensional(2D)metal organic frameworks(MOFs)are emerging as low-cost oxygen evolution reaction(OER)electrocatalysts,however,suffering aggregation and poor operation stability.Herein,ultrafine Fe_(3)O_(4) nanoparticles(diameter:6±2 nm)are homogeneously immobilized on 2D Ni based MOFs(Ni-BDC,thickness:5±1 nm)to improve the OER stability.Electronic structure modulation for enhanced catalytic activity is studied via adjusting the amount of Fe_(3)O_(4) nanoparticles on Ni-BDC.The optimal Fe_(3)O_(4)/Ni-BDC achieves the best OER performance with an overpotential of 295 mV at 10 mA cm^(-2),a Tafel slope of 47.8 mV dec^(-1) and a considerable catalytic durability of more than 40 h(less than 5 h for Ni-BDC alone).DFT calculations confirm that the active sites for Fe_(3)O_(4)/Ni-BDC are mainly contributed by Fe species with a higher oxidation state,and the potential-determining step(PDS)is the formation of the adsorbed O*species,which are facilitated in the composite.
基金Financial supports from the National Natural Science Foundation of China(22479009)the National related project。
文摘Sodium-based halide solid electrolytes offer excellent electrochemical stability and favorable interfacial compatibility,yet their low ionic conductivity at room temperature limits their application in all-solidstate Na-ion batteries(ASSNIBs),Here,we develop a series of LaCl_(3)-based sodium superionic conductors engineered through cation vacancy-concentration modulation,which facilitates the formation of a threedimensional Na+transport network and increases the density of ion-hopping sites.The optimized Na_(0.4)Ta_(0.236)La_(0.472)Cl_(3)(NTLC)electrolyte achieves a Na+conductivity of 1.38×10^(-3) S/cm at 30℃,with a reduced activation energy of 0.26 eV.It also exhibits excellent mechanical deformation and moderate high-voltage stability,resulting in enhanced interfacial compatibility.When paired directly with an uncoated NaCrO_(2) cathode,the NTLC catholyte enables ASSNIBs to cycle stably over 300 cycles with89.7%capacity retention at 0.3 C and room temperature.This work underscores the potential of vacancy-rich LaCl_(3)-based sodium superionic conductors for advancing high-performance ASSNIBs.
基金Project(2007CB613705)supported by the National Basic Research Program of China
文摘The influences of two kinds of casting modules of metal casting （MC） and expandable pattern casting （EPC） on the corrosion behavior of Mg-11Gd-3Y alloy were studied by electrochemical measurements, scanning electron microscopy （SEM） observation, X-ray diffractometry （XRD） and X-ray photoelectron spectroscopy （XPS） analysis. It is found that the quantity of the Mg 24 （Gd, Y） 5 phase in MC is more than that in EPC due to the cooling rate. There is more alloying element dissolved in the matrix compared with MC. For EPC, the galvanic corrosion effect between the matrix and the Mg 24 （Gd, Y） 5 phase decreases and the corrosion resistance increases compared with the MC. The chief corrosion mode for Mg-11Gd-3Y alloy is pitting corrosion because most of the alloying elements are transformed into intermetallic phases. The average corrosion rate of the MC alloy in the immersion test is five times higher than that of EPC alloy and yttrium is present in the product film, which will provide increased protection for Mg-11Gd-3Y alloy. The electrochemical measurements and immersion test show that the EPC process increases the corrosion resistance compared with the MC Mg-11Gd-3Y alloy.
基金Supported by the National Natural Science Foundation of China(Nos.21173034,20907006)
文摘A simple and fast route for the synthesis of metal-organic framework（MOF） particles was presented.Cu 3（BTC） 2（HKUST-1,BTC=1,3,5-benzenetricarboxylate）,one of the most well-known MOFs,was synthesized at room temperature via coordination modulation method.By adding different modulators（monocarboxylic acids） into the reaction system,the morphologies of HKUST-1 crystals were tuned from nano spheres to micro octahedrons at room temperature without any complex equipment.X-Ray diffractions and gas sorption measurements revealed highly crystalline particles with large Brunauer-Emmett-Teller（BET） surface areas（1116―1273 m^ 2 /g） and total pore volumes（0.62―0.73 cm^ 3 /g）.The significantly small particle sizes and high capacity of gas sorption are considered advantageous for envisaged application in practical industrial process.
基金MOE AcRF Tier2(2018-T2-2-005),MOE AcRF Tier1(2018-T1-005-001)A^(*)STAR AME IRG Grant SERC A1983c0027,Singapore.
文摘Semiconducting piezoelectricα-In_(2)Se_(3) and 3R MoS_(2) have attracted tremendous attention due to their unique electronic properties.Artificial van der Waals(vdWs)hetero-structures constructed withα-In_(2)Se_(3)and 3R MoS_(2)flakes have shown promising applications in optoelectronics and photocatal-ysis.Here,we present the first flexibleα-In_(2)Se_(3)/3R MoS_(2)vdWs p-n heterojunction devices for photodetection from the visible to near infrared region.These heterojunction devices exhibit an ultrahigh photoresponsivity of 2.9×10^(3)A W^(−1) and a substantial specific detectivity of 6.2×10^(10) Jones under a compressive strain of−0.26%.The photocurrent can be increased by 64%under a tensile strain of+0.35%,due to the heterojunction energy band modulation by piezoelectric polarization charges at the hetero-junction interface.This work demonstrates a feasible approach to enhancement of α-In_(2)Se_(3)/3R MoS_(2) photoelectric response through an appropriate mechanical stimulus.
