Metal-organic framework(MOF)nanostructures have emerged as a prominent class of materials in the advancement of electrochemical sensors.The rational design of bimetallic MOF-functionalized microelectrode is of importa...Metal-organic framework(MOF)nanostructures have emerged as a prominent class of materials in the advancement of electrochemical sensors.The rational design of bimetallic MOF-functionalized microelectrode is of importance for improv-ing the electrochemical performance but still in great challenge.In this work,the bimetallic FeCo-MOF nanostructures were assembled onto a gold disk ultramicroelectrode(Au UME,5.2μm in diameter)via an in-situ electrodeposition method,which enhanced the sensitive detection of epinephrine(EP).The in-situ electrodeposited FeCo-MOF exhibited a character-istic nanoflower-like morphology and was uniformly dispersed on the Au UME.The FeCo-MOF/Au UME demonstrated excellent electrochemical performance on the detection of EP with a high sensitivity of 36.93μA·μmol^(-1)·L·cm^(-2)and a low detection limit of 1.28μmol·L^(-1).It can be attributed to the nonlinear diffusion of EP onto the ultra-micro working substrate,coupled with synergistical catalytic activity of the bimetallic Fe,Co within MOF structure.Furthermore,the FeCo-MOF/Au UME has been successful applied to the analysis of EP in human serum samples,yielding high recovery rates.These results not only contribute to the expansion of the research area of electrochemical sensors,but also provide novel insights and directions into the development of high-performance MOF-based electrochemical sensors.展开更多
Metal-ceramic composites combine the excellent properties of metals and ceramics,which have high strength,stability,and corrosion re-sistance.Al_(2)O_(3)/FeCo composites have been proven to be useful in ap-plications ...Metal-ceramic composites combine the excellent properties of metals and ceramics,which have high strength,stability,and corrosion re-sistance.Al_(2)O_(3)/FeCo composites have been proven to be useful in ap-plications such as catalysts,mi-crowave absorption materials,and enhanced permeability dielectric.The understanding of the mechani-cal properties and dynamics at the atomic scale of the Al_(2)O_(3)/FeCo in-terface can promote the design and exploitment of metal-ceramic composites.In this work,we have obtained Young’s modulus and diffusion coefficient of the Al_(2)O_(3)/FeCo interface using molecular dynamics simulation,elucidated the structural characteristics of the Al_(2)O_(3)/FeCo interface at the atomic scale,and investigated the impact of atomic magnetism and the exter-nal magnetic field on the interface.Simulated results show that Young’s modulus of the Al_(2)O_(3)/FeCo interface is significantly improved compared with pure Al_(2)O_(3)and FeCo alloy at room and high temperatures.When the atomic magnetism and the external magnetic field are applied,Young’s modulus of the Al_(2)O_(3)/FeCo interface further increases to 612 GPa at 300 K and 602 GPa at 500 K.Moreover,the average density,diffusion coefficient,and radial distri-bution function are found to be modified substantially.This study will shed light on the atom-istic investigations of the metal-ceramic composites.展开更多
Ultra-wide absorption band and flexibility are needed in multi-scenario applications,however,current electromagnetic wave absorption materials(EMWAMs)are not capable enough to deliver due to rigid structure.Here,we ha...Ultra-wide absorption band and flexibility are needed in multi-scenario applications,however,current electromagnetic wave absorption materials(EMWAMs)are not capable enough to deliver due to rigid structure.Here,we have designed a porous flexible mat composed of Zn-doped carbon(Zn@C)nanofibers(NFs)having encapsulated uniformly dispersed FeCo nanoparticles(NPs)(FeCo/Zn@C)as ultra-wideband absorber.During the electrospinning,the Fe^(3+),Co^(2+)and Zn^(2+)are uniformly immobilized within the NFs nanocrystallization process.Subsequently,the Kirkendall effect is deployed to trigger the generation of FeCo NPs and porous framework under thermal annealing.The FeCo/Zn@C NFs effectively favor magnetic-dielectric synergies due to the coexistence of magnetic FeCo NPs and dielectric carbon components.One-dimensional porous fiber prolongs the attenuation path and enhances multi-scattering and reflection.While the FeCo NPs encapsulated in Zn-doped carbon NFs provide abundant dipole and interfacial polarization.These favorable factors synergistically enhance absorption performance,resulting in a reflection loss value of-71.58 dB.Moreover,by varying the thickness of absorbers,effective absorption bandwidth spans from 4.26 to 18.00 GHz.Hence,this work offers innovative insights for fabricating advanced EMWAMs.展开更多
The interface mechanism between catalyst and carbon substrate has been the focus of research.In this paper,the FeCo alloy embedded N,S co-doped carbon substrate bifunctional catalyst(FeCo/S-NC)is obtained by a simple ...The interface mechanism between catalyst and carbon substrate has been the focus of research.In this paper,the FeCo alloy embedded N,S co-doped carbon substrate bifunctional catalyst(FeCo/S-NC)is obtained by a simple one-step pyrolysis strategy.The experimental results and density functional theory(DFT)calculation show that the formation of FeCo alloy is conducive to promoting electron transfer,and the introduction of S atom can enhance the interaction between FeCo alloy and carbon substrate,thus inhibiting the migration and agglomeration of particles on the surface of carbon material.The FeCo/SNC catalysts show outstanding performance for oxygen reduction reaction(ORR)and oxygen evolution reaction(OER).FeCo/S-NC shows a high half-wave potential(E_(1/2)=0.8823 V)for ORR and a low overpotential at 10 mA cm^(-2)(E_(j=10)=299 mV)for OER.In addition,compared with Pt/C+RuO_(2) assembled Zn-air battery(ZAB),the FeCo/S-NC assembled ZAB exhibits a larger power density(198.8 mW cm^(-2)),a higher specific capacity(786.1 mA h g_(zn)~(-1)),and ultra-stable cycle performance.These results confirm that the optimized composition and the interfacial interaction between catalyst and carbon substrate synergistically enhance the electrochemical performance.展开更多
基金support from the National Key Research and Development Program of China(2021YFB3201400,2021YFB3201401,2020YFC1908602)the National Natural Science Foundation of China(21904001 and 61774159)+1 种基金the Anhui Provincial Natural Science Foundation(2008085QF288)the Scientific Research Foundation for the Returned Overseas Chinese Scholars,Anhui Province(2020LCX032).
文摘Metal-organic framework(MOF)nanostructures have emerged as a prominent class of materials in the advancement of electrochemical sensors.The rational design of bimetallic MOF-functionalized microelectrode is of importance for improv-ing the electrochemical performance but still in great challenge.In this work,the bimetallic FeCo-MOF nanostructures were assembled onto a gold disk ultramicroelectrode(Au UME,5.2μm in diameter)via an in-situ electrodeposition method,which enhanced the sensitive detection of epinephrine(EP).The in-situ electrodeposited FeCo-MOF exhibited a character-istic nanoflower-like morphology and was uniformly dispersed on the Au UME.The FeCo-MOF/Au UME demonstrated excellent electrochemical performance on the detection of EP with a high sensitivity of 36.93μA·μmol^(-1)·L·cm^(-2)and a low detection limit of 1.28μmol·L^(-1).It can be attributed to the nonlinear diffusion of EP onto the ultra-micro working substrate,coupled with synergistical catalytic activity of the bimetallic Fe,Co within MOF structure.Furthermore,the FeCo-MOF/Au UME has been successful applied to the analysis of EP in human serum samples,yielding high recovery rates.These results not only contribute to the expansion of the research area of electrochemical sensors,but also provide novel insights and directions into the development of high-performance MOF-based electrochemical sensors.
基金supported by the National Natural Science Foundation of China(Nos.22173057,52130204,12074241,11929401,12311530675)Science and Technology Commission of Shanghai Municipality(Nos.21JC1402700,22XD1400900,20501130600,21JC1402600)High-Performance Computing Center,Shanghai Technical Service Center of Science and Engineering Computing,Shanghai University。
文摘Metal-ceramic composites combine the excellent properties of metals and ceramics,which have high strength,stability,and corrosion re-sistance.Al_(2)O_(3)/FeCo composites have been proven to be useful in ap-plications such as catalysts,mi-crowave absorption materials,and enhanced permeability dielectric.The understanding of the mechani-cal properties and dynamics at the atomic scale of the Al_(2)O_(3)/FeCo in-terface can promote the design and exploitment of metal-ceramic composites.In this work,we have obtained Young’s modulus and diffusion coefficient of the Al_(2)O_(3)/FeCo interface using molecular dynamics simulation,elucidated the structural characteristics of the Al_(2)O_(3)/FeCo interface at the atomic scale,and investigated the impact of atomic magnetism and the exter-nal magnetic field on the interface.Simulated results show that Young’s modulus of the Al_(2)O_(3)/FeCo interface is significantly improved compared with pure Al_(2)O_(3)and FeCo alloy at room and high temperatures.When the atomic magnetism and the external magnetic field are applied,Young’s modulus of the Al_(2)O_(3)/FeCo interface further increases to 612 GPa at 300 K and 602 GPa at 500 K.Moreover,the average density,diffusion coefficient,and radial distri-bution function are found to be modified substantially.This study will shed light on the atom-istic investigations of the metal-ceramic composites.
基金supported by the National Natural Science Foundation of China(No.51972045).
文摘Ultra-wide absorption band and flexibility are needed in multi-scenario applications,however,current electromagnetic wave absorption materials(EMWAMs)are not capable enough to deliver due to rigid structure.Here,we have designed a porous flexible mat composed of Zn-doped carbon(Zn@C)nanofibers(NFs)having encapsulated uniformly dispersed FeCo nanoparticles(NPs)(FeCo/Zn@C)as ultra-wideband absorber.During the electrospinning,the Fe^(3+),Co^(2+)and Zn^(2+)are uniformly immobilized within the NFs nanocrystallization process.Subsequently,the Kirkendall effect is deployed to trigger the generation of FeCo NPs and porous framework under thermal annealing.The FeCo/Zn@C NFs effectively favor magnetic-dielectric synergies due to the coexistence of magnetic FeCo NPs and dielectric carbon components.One-dimensional porous fiber prolongs the attenuation path and enhances multi-scattering and reflection.While the FeCo NPs encapsulated in Zn-doped carbon NFs provide abundant dipole and interfacial polarization.These favorable factors synergistically enhance absorption performance,resulting in a reflection loss value of-71.58 dB.Moreover,by varying the thickness of absorbers,effective absorption bandwidth spans from 4.26 to 18.00 GHz.Hence,this work offers innovative insights for fabricating advanced EMWAMs.
基金supported by the National Natural Science Foundation of China(52374301 and 22279030)the Fundamental Research Funds for the Central Universities(N2223037)+1 种基金Hebei Key Laboratory of Dielectric and Electrolyte Functional Material,Northeastern University at Qinhuangdao(HKDEFM2021201)the Performance subsidy fund for the Key Laboratory of Dielectric and Electrolyte Functional Material Hebei Province(22567627H)。
文摘The interface mechanism between catalyst and carbon substrate has been the focus of research.In this paper,the FeCo alloy embedded N,S co-doped carbon substrate bifunctional catalyst(FeCo/S-NC)is obtained by a simple one-step pyrolysis strategy.The experimental results and density functional theory(DFT)calculation show that the formation of FeCo alloy is conducive to promoting electron transfer,and the introduction of S atom can enhance the interaction between FeCo alloy and carbon substrate,thus inhibiting the migration and agglomeration of particles on the surface of carbon material.The FeCo/SNC catalysts show outstanding performance for oxygen reduction reaction(ORR)and oxygen evolution reaction(OER).FeCo/S-NC shows a high half-wave potential(E_(1/2)=0.8823 V)for ORR and a low overpotential at 10 mA cm^(-2)(E_(j=10)=299 mV)for OER.In addition,compared with Pt/C+RuO_(2) assembled Zn-air battery(ZAB),the FeCo/S-NC assembled ZAB exhibits a larger power density(198.8 mW cm^(-2)),a higher specific capacity(786.1 mA h g_(zn)~(-1)),and ultra-stable cycle performance.These results confirm that the optimized composition and the interfacial interaction between catalyst and carbon substrate synergistically enhance the electrochemical performance.
