Sodium-ion batteries (SIBs) have attracted increasing attention in the past decades, because of high over-all abundance of precursors, their even geographical distribution, and low cost. Na3V2(PO4)3 (NVP), atypi...Sodium-ion batteries (SIBs) have attracted increasing attention in the past decades, because of high over-all abundance of precursors, their even geographical distribution, and low cost. Na3V2(PO4)3 (NVP), atypical sodium super ion conductor (NASlCON)-based electrode material, exhibits pronounced structuralstability, exceptionally high ion conductivity, rendering it a most promising electrode for sodium storage.However. the comparatively low electronic conductivity makes the theoretical capacity of NVP cannot befully accessible even at comparatively low rates, presenting a major drawback for further practical ap-plications, especially when high rate capability is especially important. Thus, many endeavors have beenconformed to increase the surface and intrinsic electrical conductivity of NVP by coating the active mate-rials with a conductive carbon layer, downsizing the NVP particles, combining the NVP particle with vari-ous carbon materials and ion doping strategy. In this review, to get a better understanding on the sodiumstorage in NVP, we firstly present 4 distinct crystal structures in the temperature range of-30℃-225℃ namely α-NVP, β-NVP, β′-NVP and γ-NVP. Moreover, we give an overview of recent approaches to en-hance the surface electrical conductivity and intrinsic electrical conductivity of NVP. Finally, some poten-tial applications of NVP such as in all-climate environment and PHEV, EV fields have been prospected.展开更多
The effect of bismuth (Bi) for both VO2+/VO2+ and V3+/V2+ redox couples in vanadium flow batteries (VFBs) has been investigated by directly introducing Bi on the surface of carbon felt (CF). The results show that Bi h...The effect of bismuth (Bi) for both VO2+/VO2+ and V3+/V2+ redox couples in vanadium flow batteries (VFBs) has been investigated by directly introducing Bi on the surface of carbon felt (CF). The results show that Bi has no catalytic effect for VO2+/VO2(+) redox couple. During the first charge process, Bi is oxidized to Bi3+ (never return back to Bi metal in the subsequent cycles) due to the low standard redox potential of 0.308 V (vs. SHE) for Bi3+/Bi redox couple compared with VO2+/VO2+ redox couple and Bi3+ exhibit no (or neglectable) electro-catalytic activity. Additionally, the relationship between Bi loading and electrochemical activity for V3+/V2+ redox couple was studied in detail. 2 wt% Bi-modified carbon felt (2%-BiCF) exhibits the highest electrochemical activity. Using it as negative electrode, a high energy efficiency (EE) of 79.0% can be achieved at a high current density of 160 mA/cm(2), which is 5.5% higher than the pristine one. Moreover, the electrolyte utilization ratio is also increased by more than 30%. Even the cell operated at 140 mA/cm(2) for over 300 cycles, the EE can reach 80.9% without obvious fluctuation and attenuation, suggesting excellent catalytic activity and electrochemical stability in VFBs. (C) 2016 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. and Science Press. All rights reserved.展开更多
Ethyl-(2,2,2-trifluoroethyl)carbonate(ETFEC)is investigated as a solvent component in high-voltage electrolytes for LiNi0.5Mn1.5O4(LNMO).Our results show that the self-discharge behavior and the high temperature cycle...Ethyl-(2,2,2-trifluoroethyl)carbonate(ETFEC)is investigated as a solvent component in high-voltage electrolytes for LiNi0.5Mn1.5O4(LNMO).Our results show that the self-discharge behavior and the high temperature cycle performance can be significantly improved by the addition of 10%ETFEC into the normal carbonate electrolytes,e.g.,the capacity retention improved from 65.3%to 77.1%after 200 cycles at 60℃.The main reason can be ascribed to the high stability of ETFEC which prevents large oxidation of the electrolyte on the cathode surface.In addition,we also explore the feasibility of electrolytes using single fluoriated-solvents with and without additives.Our results show that the cycle performance of LNMO material can be greatly improved in 1 MLiPF6+pure ETFEC-solvent system with 2 wt%ethylene carbonate(EC)or ethylene sulfate(DTD).The capacity retention of the LNMO materials is 93%after 300 cycles,even better than that of carbonate-based electrolytes.It is shown that the additives are oxidized on the surface of LNMO particles and contribute to the formation of cathode/electrolyte interphase(CEI)films.This composite CEI film plays a crucial role in suppressing the serious decomposition of the electrolyte at high voltage.展开更多
Hierarchical magnetic-dielectric composites are promising functional materials with prospective applications in microwave absorption(MA)field.Herein,a three-dimension hierarchical“nanotubes on microrods,”core–shell...Hierarchical magnetic-dielectric composites are promising functional materials with prospective applications in microwave absorption(MA)field.Herein,a three-dimension hierarchical“nanotubes on microrods,”core–shell magnetic metal–carbon composite is rationally constructed for the first time via a fast metal–organic frameworksbased ligand exchange strategy followed by a carbonization treatment with melamine.Abundant magnetic CoFe nanoparticles are embedded within one-dimensional graphitized carbon/carbon nanotubes supported on micro-scale Mo2N rod(Mo2N@CoFe@C/CNT),constructing a special multi-dimension hierarchical MA material.Ligand exchange reaction is found to determine the formation of hierarchical magnetic-dielectric composite,which is assembled by dielectric Mo2N as core and spatially dispersed CoFe nanoparticles within C/CNTs as shell.Mo2N@CoFe@C/CNT composites exhibit superior MA performance with maximum reflection loss of−53.5 dB at 2 mm thickness and show a broad effective absorption bandwidth of 5.0 GHz.The Mo2N@CoFe@C/CNT composites hold the following advantages:(1)hierarchical core–shell structure offers plentiful of heterojunction interfaces and triggers interfacial polarization,(2)unique electronic migration/hop paths in the graphitized C/CNTs and Mo2N rod facilitate conductive loss,(3)highly dispersed magnetic CoFe nanoparticles within“tubes on rods”matrix build multi-scale magnetic coupling network and reinforce magnetic response capability,confirmed by the off-axis electron holography.展开更多
Lithium-sulfur (Li-S) batteries have great potential as an electrochemical energy storage system because of the high theoretical energy density and acceptable cost of financial and environment.However,the shuttle effe...Lithium-sulfur (Li-S) batteries have great potential as an electrochemical energy storage system because of the high theoretical energy density and acceptable cost of financial and environment.However,the shuttle effect leads to severe capacity fading and low coulombic efficiency.Here,graphitic carbon nitride(g-C3N4) is designed and prepared via a feasible and simple method from trithiocyanuric acid (TTCA) to anchor the polysulfides and suppress the shuttle effect.The obtained g-C3N4 exhibits strong chemical interaction with polysulfides due to its high N-doping of 56.87 at%,which is beneficial to improve the cycling stability of Li-S batteries.Moreover,the novel porous framework and high specific surface area of g-C3N4 also provide fast ion transport and broad reaction interface of sulfur cathode,facilitating high capacity output and superior rate performance of Li-S batteries.As a result,Li-S batteries assembled with g-C3N4 can achieve high discharge capacity of 1200 mAh/g at 0.2 C and over 800 mAh/g is remained after 100 cycles with a coulombic efficiency more than 99.5%.When the C-rate rises to 5 C,the reversible capacity of Li-S batteries can still maintain at 607mAh/g.展开更多
Intrinsic electric-magnetic property and special nano-micro architecture of functional materials have a significant effect on its electromagnetic wave energy conversion,especially in the microwave absorption(MA) field...Intrinsic electric-magnetic property and special nano-micro architecture of functional materials have a significant effect on its electromagnetic wave energy conversion,especially in the microwave absorption(MA) field.Herein,porous Ni1-xCox@Carbon composites derived from metal-organic framework(MOF)were successfully synthesized via solvothermal reaction and subsequent annealing treatments.Benefiting from the coordination,carbonized bimetallic Ni-Co-MOF maintained its initial skeleton and transformed into magnetic-carbon composites with tunable nano-micro structure.During the thermal decomposition,generated magnetic particles/clusters acted as a catalyst to promote the carbon sp^2 arrangement,forming special core-shell architecture.Therefore,pure Ni@C microspheres displayed strong MA behaviors than other Ni1-xCox@Carbon composites.Surprisingly,magnetic-dielectric Ni@C composites possessed the strongest reflection loss value-59.5 dB and the effective absorption frequency covered as wide as 4.7 GHz.Meanwhile,the MA capacity also can be boosted by adjusting the absorber content from 25% to 40%.Magnetic-dielectric synergy effect of MOF-derived Ni1-xCox@Carbon microspheres was confirmed by the off-axis electron holography technology making a thorough inquiry in the MA mechanism.展开更多
Cathodic electrocatalytic reactions, such as hydrogen evolution and CO_(2)/N_(2) reduction, are the key processes that store intermittent electricity into stable chemical energy. Although a great progress has been mad...Cathodic electrocatalytic reactions, such as hydrogen evolution and CO_(2)/N_(2) reduction, are the key processes that store intermittent electricity into stable chemical energy. Although a great progress has been made to boost activity and selectivity via elaborative catalyst design, the structure–property relationships have not been sufficiently understood in the context of surface reconfiguration under working conditions. Recent efforts devoted to tracking dynamic evolution of electrocatalysts using in-situ and/or operando techniques gave new insights into the real structure and working mechanism of active sites,and provided principles to design better catalysts. The achievement of cathodic electrocatalysts in this subject is herein summarized, focusing on the correlations between reconstructed surface and electrocatalytic performance. Briefly, the thermodynamics of reconstruction at cathodes is discussed at first, and then the representative progresses in H_(2) evolution and CO_(2)/N_(2) reduction are introduced in sequence to acquire insights into electrochemical processes on in-situ reconfigured surfaces or interfaces. Finally, a perspective is offered to guide future investigations. This review is anticipated to shed some new light on in-depth understanding cathodic electrocatalysis and exploiting prominent electrocatalysts.展开更多
The quest of exact and nonperturbative methods on quantum dissipation with nonlinear coupling environments remains in general a great challenge.In this review we present a comprehensive account on two approaches to th...The quest of exact and nonperturbative methods on quantum dissipation with nonlinear coupling environments remains in general a great challenge.In this review we present a comprehensive account on two approaches to the entangled system-and-environment dynamics,in the presence of linear-plus-quadratic coupling bath.One is the dissipaton-equation-ofmotion(DEOM)theory that has been extended recently to treat the nonlinear coupling environment.Another is the extended Fokker-Planck quantum master equation(FP-QME)approach that will be constructed in this work,based on its DEOM correspondence.We closely compare these two approaches,with the focus on the underlying quasi-particle picture,physical implications,and implementations.展开更多
Fabrication of heterostructure composed of one-dimensional(1D)and 2D semiconductors has inspired extensive interest in promoting photogenerated charge separation as well as performances of solar fuel production,but it...Fabrication of heterostructure composed of one-dimensional(1D)and 2D semiconductors has inspired extensive interest in promoting photogenerated charge separation as well as performances of solar fuel production,but it is still challenging for(oxy)nitride photocatalysts due to their uncontrollable ammonia thermal preparative process.In this work,we report a synthesis on heterostructure of Ta_(3)N_(5)nanorods and CaTaO_(2)N(CTON)nanosheets(denoted as Ta_(3)N_(5)/CTON)by directly nitriding a 2D Dion-Jacobson(DJ)type of perovskite KCa_(2)Ta_(3)O_(10)(KCTO)precursor under the assistance of K_(2)CO_(3)flux.It is demonstrated that the 2D morphology of KCTO can be well inherited to get 2D CTON,and the Ta-rich(nonstoichiometric ratio of Ca:Ta compared to CTON)feature of the KCTO as well as the easy evaporation of K species results in the formation of 1D Ta_(3)N_(5)nanorods.Meanwhile,the formation of intermediate species K_(2)Ca_(2)Ta_(3)O_(9)N owning similar crystal lattice as Ta_(3)N_(5)was detected and deduced to be responsible for the generation of Ta_(3)N_(5)nanorods and observation of intimate interface between CTON and Ta_(3)N_(5).Benefitting from the formation of special 1D/2D type-II heterostructure,obviously promoted charge separation as well as photocatalytic water splitting performance can be obtained.Extended discussion demonstrates the generality of the hard-template preparative strategy developed here.To our knowledge,this should be the first fabrication of 1D/2D heterostructure for the(oxy)nitride semiconductors,and the developed hard-template strategy may provide an alternative way of fabricating heterostructures of other semiconductors prepared at high temperature.展开更多
The hybridization between the outmost s orbitals of metal(Bi^(3+),Sn^(2+),Pb^(2+),Ag^(+))and O 2 p orbitals has been widely employed to develop innovative semiconductors with upshift valence band as well as extended v...The hybridization between the outmost s orbitals of metal(Bi^(3+),Sn^(2+),Pb^(2+),Ag^(+))and O 2 p orbitals has been widely employed to develop innovative semiconductors with upshift valence band as well as extended visible light response,but it is still challenging to obtain photocatalyst with absorption edge of above 550 nm.Here we report a novel Sn^(2+)-based oxyfluoride Sn_(2)TiNbO_6 F(STNOF)photocatalyst with a pyrochlore structure to exhibit an extended absorption edge to 650 nm and dual functionalities of both water reduction and oxidation.Density functional theory calculations suggest that the unprecedented broad-spectrum response of STNOF is mainly ascribed to the strengthened hybridization between O 2 p and Sn 5 s orbitals remarkably upshifting the valence band,which is caused by the distortion and compressive strain in the Sn06 F2 dodecahedron with second-order Jahn-Teller effect due to partial fluorine substitution.The structural distortion and compressive strain are experimentally confirmed by the Fourier-transformed extended X-ray absorption fine spectra.As probe tests of the photocatalytic functionalities,water reduction and oxidation half reactions were examined to see obvious H_(2)and O_(2)evolution under visible light irradiation.This work may provide an alternative strategy of developing extended visible light responsive semiconductors for promising solar energy conversion.展开更多
In the pioneering work by R.A.Marcus,the solvation effect on electron transfer(ET)processes was investigated,giving rise to the celebrated nonadiabatic ET rate formula.In this work,on the basis of the thermodynamic so...In the pioneering work by R.A.Marcus,the solvation effect on electron transfer(ET)processes was investigated,giving rise to the celebrated nonadiabatic ET rate formula.In this work,on the basis of the thermodynamic solvation potentials analysis,we reexamine Marcus’formula with respect to the Rice-Ramsperger-Kassel-Marcus(RRKM)theory.Interestingly,the obtained RRKM analogue,which recovers the original Marcus’rate that is in a linear solvation scenario,is also applicable to the nonlinear solvation scenarios,where the multiple curve-crossing of solvation potentials exists.Parallelly,we revisit the corresponding Fermi’s golden rule results,with some critical comments against the RRKM analogue proposed in this work.For illustration,we consider the quadratic solvation scenarios,on the basis of physically well-supported descriptors.展开更多
Ultrathin free-standing electrospun carbon nanofiber web(ECNFW) used for the electrodes of the vanadium flow battery(VFB) has been fabricated by the electrospinning technique followed by the carbonization process ...Ultrathin free-standing electrospun carbon nanofiber web(ECNFW) used for the electrodes of the vanadium flow battery(VFB) has been fabricated by the electrospinning technique followed by the carbonization process in this study to reduce the ohmic polarization of the VFB. The microstructure, surface chemistry and electrochemical performance of ECNFW carbonized at various temperatures from 800 to 1400 °C have been investigated. The results show that ECNFW carbonized at 1100 °C exhibits the highest electrocatalytic activity toward the V;/V;redox reaction, and its electrocatalytic activity decreases along with the increase of carbonization temperature due to the drooping of the surface functional groups.While for the VO;/VO;redox couple, the electrocatalytic activity of ECNFW carbonized above 1100 °C barely changes as the carbonization temperature rises. It indicates that the surface functional groups could function as the reaction sites for the V;/V;redox couple, but have not any catalytic effect for the VO;/VO;redox couple. And the single cell test result suggests that ECNFW carbonized at 1100 °C is a promising material as the VFB electrode and the VFB with ECNFW electrodes obtains a super low internal resistance of 250 mΩ cm;.展开更多
Oxygen evolution reaction(OER) is one of the most important reactions in the energy storage devices such as metal–air batteries and unitized regenerative fuel cells(URFCs). However, the kinetically sluggishness o...Oxygen evolution reaction(OER) is one of the most important reactions in the energy storage devices such as metal–air batteries and unitized regenerative fuel cells(URFCs). However, the kinetically sluggishness of OER and the high prices as well as the scarcity of the most active precious metal electrocatalysts are the major bottleneck in these devices. Developing low-cost non-precious metal catalysts with high activity and stability for OER is highly desirable. A facile, in situ template method combining the dodecyl benzene sulfuric acid sodium(SDBS) assisted hydrothermal process with subsequent high-temperature treatment was developed to prepare porous Co3O4 with improved surface area and hierarchical porous structure as precious catalysts alternative for oxygen evolution reaction(OER). Due to the unique structure, the as-prepared catalyst shows higher electrocatalytic activity than Co3O4 prepared by traditional thermal-decomposition method(noted as Co3O4-T) and commercial IrO2 catalyst for OER in 0.1M KOH aqueous solution. Moreover, it displays improved stability than Co3O4-T. The results demonstrate a highly efficient, scalable, and low cost method for developing highly active and stable OER electrocatalysts in alkaline solutions.展开更多
Amorphous alloys,also known as metallic glasses,are solid metallic materials having long-range disordered atomic structures.Compared to crystalline alloys,amorphous alloys not only have metallic characters,but also po...Amorphous alloys,also known as metallic glasses,are solid metallic materials having long-range disordered atomic structures.Compared to crystalline alloys,amorphous alloys not only have metallic characters,but also possess several distinct properties associated to the amorphous structure,such as isotropy,composition flexibility,unsaturated surface,etc.As a result,amorphous alloys offer a class of highly promising materials for catalyzing electrochemical reactions.In this minireview,the preparation,characterization and electrocatalytic performances of a variety of metallic amorphous alloy materials are summarized.The influences of the amorphous alloy structure on different electrochemical reactions are discussed.Finally,a summary on the advantages and challenges of amorphous alloys in electrocatalysis is provided,along with some perspectives about the future research directions.展开更多
Developing carbon-based electrocatalysts with excellent N2 adsorption and activation capability holds the key to achieve highly efficient nitrogen reduction reaction(NRR)for reaching its practical application.Here,we ...Developing carbon-based electrocatalysts with excellent N2 adsorption and activation capability holds the key to achieve highly efficient nitrogen reduction reaction(NRR)for reaching its practical application.Here,we report a highly active electrocatalyst--metal-free pyrrolic-N dominated N,S co-doped carbon(pyrr-NSC)for NRR.Based on theoretical and experimental results,it is confirmed that the N and S-dopants practice a working-in-tandem mechanism on pyrr-NSC,where the N-dopants are utilized to create electropositive C sites for enhancing N2 adsorption and the S-dopants are employed to induce electron backdonation for facilitating N2 activation.The synergistic effect of the pyrrolic-N and S-dopants can also suppress the irritating hydrogen evolution reaction,further boosting the NRR performance.This work gives an indication that the combination of two different dopants on electrocatalyst can enhance NRR performance by working in the two tandem steps-the adsorption and activation of N2 molecules,providing a new strategy for NRR electrocatalyst design.展开更多
Metal nanocatalysts have attracted widespread attention in heterogeneous catalysis for their remarkable catalytic performance.The electronic properties of metal nanoparticles govern the orbital hybridization and charg...Metal nanocatalysts have attracted widespread attention in heterogeneous catalysis for their remarkable catalytic performance.The electronic properties of metal nanoparticles govern the orbital hybridization and charge transfer between active metals and reactants;meanwhile,the local geometries of metal nanoparticles could also have a substantial impact on chemical bond breaking and bond making.展开更多
Harvesting clean energy from water evaporation has been extensively investigated due to its sustainability.To achieve high efficiency,energy conversion materials should contain multiple features which are difficult to...Harvesting clean energy from water evaporation has been extensively investigated due to its sustainability.To achieve high efficiency,energy conversion materials should contain multiple features which are difficult to be simultaneously obtained from single-component materials.Here we use composite laminar membranes assembled by nanosheets of graphene oxide and mica,and find a sustained power density induced by water evaporation that is two orders of magnitude larger than that from membranes made by either of the components.The power output is attributed to selective proton transport driven by water evaporation through the interlayer nanochannels in the membranes.This process relies on the synergistic effects from negatively charged and hydrophilic mica surfaces that are important for proton selectivity and water transport,and the tunable electrical conductivity of graphene oxide that provides optimized internal resistance.The demonstrated composite membranes offer a strategy of enhancing power generation by combining the advantages from each of their components.展开更多
基金financial support from the National Natural Science Foundation of China (No.21501171,51403209,21406221,51177156/E0712)
文摘Sodium-ion batteries (SIBs) have attracted increasing attention in the past decades, because of high over-all abundance of precursors, their even geographical distribution, and low cost. Na3V2(PO4)3 (NVP), atypical sodium super ion conductor (NASlCON)-based electrode material, exhibits pronounced structuralstability, exceptionally high ion conductivity, rendering it a most promising electrode for sodium storage.However. the comparatively low electronic conductivity makes the theoretical capacity of NVP cannot befully accessible even at comparatively low rates, presenting a major drawback for further practical ap-plications, especially when high rate capability is especially important. Thus, many endeavors have beenconformed to increase the surface and intrinsic electrical conductivity of NVP by coating the active mate-rials with a conductive carbon layer, downsizing the NVP particles, combining the NVP particle with vari-ous carbon materials and ion doping strategy. In this review, to get a better understanding on the sodiumstorage in NVP, we firstly present 4 distinct crystal structures in the temperature range of-30℃-225℃ namely α-NVP, β-NVP, β′-NVP and γ-NVP. Moreover, we give an overview of recent approaches to en-hance the surface electrical conductivity and intrinsic electrical conductivity of NVP. Finally, some poten-tial applications of NVP such as in all-climate environment and PHEV, EV fields have been prospected.
基金the financial support from the China Natural Science Foundation(Grant nos.51403209,21406221,21206158,21476224,21406219 and 51361135701)the Outstanding Young Scientist Foundation,Chinese Academy of Sciences(CAS)+2 种基金Supported by the Key Research Program of the Chinese Academy of Sciences(KG2D-EW-602-2)Science and Technology Service Network Initiative(KFJ-EW-STS-108)Dalian Municipal Outstanding Young Talent Foundation(2014J11JH131)
文摘The effect of bismuth (Bi) for both VO2+/VO2+ and V3+/V2+ redox couples in vanadium flow batteries (VFBs) has been investigated by directly introducing Bi on the surface of carbon felt (CF). The results show that Bi has no catalytic effect for VO2+/VO2(+) redox couple. During the first charge process, Bi is oxidized to Bi3+ (never return back to Bi metal in the subsequent cycles) due to the low standard redox potential of 0.308 V (vs. SHE) for Bi3+/Bi redox couple compared with VO2+/VO2+ redox couple and Bi3+ exhibit no (or neglectable) electro-catalytic activity. Additionally, the relationship between Bi loading and electrochemical activity for V3+/V2+ redox couple was studied in detail. 2 wt% Bi-modified carbon felt (2%-BiCF) exhibits the highest electrochemical activity. Using it as negative electrode, a high energy efficiency (EE) of 79.0% can be achieved at a high current density of 160 mA/cm(2), which is 5.5% higher than the pristine one. Moreover, the electrolyte utilization ratio is also increased by more than 30%. Even the cell operated at 140 mA/cm(2) for over 300 cycles, the EE can reach 80.9% without obvious fluctuation and attenuation, suggesting excellent catalytic activity and electrochemical stability in VFBs. (C) 2016 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. and Science Press. All rights reserved.
基金financially supported by National Key Research and Development Program of China(Grant no.2018YFB010440)the National Natural Science Foundation of China(Grant nos.21761132030,21621091).
文摘Ethyl-(2,2,2-trifluoroethyl)carbonate(ETFEC)is investigated as a solvent component in high-voltage electrolytes for LiNi0.5Mn1.5O4(LNMO).Our results show that the self-discharge behavior and the high temperature cycle performance can be significantly improved by the addition of 10%ETFEC into the normal carbonate electrolytes,e.g.,the capacity retention improved from 65.3%to 77.1%after 200 cycles at 60℃.The main reason can be ascribed to the high stability of ETFEC which prevents large oxidation of the electrolyte on the cathode surface.In addition,we also explore the feasibility of electrolytes using single fluoriated-solvents with and without additives.Our results show that the cycle performance of LNMO material can be greatly improved in 1 MLiPF6+pure ETFEC-solvent system with 2 wt%ethylene carbonate(EC)or ethylene sulfate(DTD).The capacity retention of the LNMO materials is 93%after 300 cycles,even better than that of carbonate-based electrolytes.It is shown that the additives are oxidized on the surface of LNMO particles and contribute to the formation of cathode/electrolyte interphase(CEI)films.This composite CEI film plays a crucial role in suppressing the serious decomposition of the electrolyte at high voltage.
基金This work was supported by the Ministry of Science and Technology of China(973 Project No.2018YFA0209102)the National Natural Science Foundation of China(11727807,51725101,51672050,61790581).
文摘Hierarchical magnetic-dielectric composites are promising functional materials with prospective applications in microwave absorption(MA)field.Herein,a three-dimension hierarchical“nanotubes on microrods,”core–shell magnetic metal–carbon composite is rationally constructed for the first time via a fast metal–organic frameworksbased ligand exchange strategy followed by a carbonization treatment with melamine.Abundant magnetic CoFe nanoparticles are embedded within one-dimensional graphitized carbon/carbon nanotubes supported on micro-scale Mo2N rod(Mo2N@CoFe@C/CNT),constructing a special multi-dimension hierarchical MA material.Ligand exchange reaction is found to determine the formation of hierarchical magnetic-dielectric composite,which is assembled by dielectric Mo2N as core and spatially dispersed CoFe nanoparticles within C/CNTs as shell.Mo2N@CoFe@C/CNT composites exhibit superior MA performance with maximum reflection loss of−53.5 dB at 2 mm thickness and show a broad effective absorption bandwidth of 5.0 GHz.The Mo2N@CoFe@C/CNT composites hold the following advantages:(1)hierarchical core–shell structure offers plentiful of heterojunction interfaces and triggers interfacial polarization,(2)unique electronic migration/hop paths in the graphitized C/CNTs and Mo2N rod facilitate conductive loss,(3)highly dispersed magnetic CoFe nanoparticles within“tubes on rods”matrix build multi-scale magnetic coupling network and reinforce magnetic response capability,confirmed by the off-axis electron holography.
基金the financial support from the National Natural Science Foundation of China(Nos.51673199 and 51677176)Youth Innovation Promotion Association of CAS(2015148)+1 种基金Innovation Foundation of DICP(ZZBS201615,ZZBS201708)Dalian Science and Technology Star Program(2016RQ026)。
文摘Lithium-sulfur (Li-S) batteries have great potential as an electrochemical energy storage system because of the high theoretical energy density and acceptable cost of financial and environment.However,the shuttle effect leads to severe capacity fading and low coulombic efficiency.Here,graphitic carbon nitride(g-C3N4) is designed and prepared via a feasible and simple method from trithiocyanuric acid (TTCA) to anchor the polysulfides and suppress the shuttle effect.The obtained g-C3N4 exhibits strong chemical interaction with polysulfides due to its high N-doping of 56.87 at%,which is beneficial to improve the cycling stability of Li-S batteries.Moreover,the novel porous framework and high specific surface area of g-C3N4 also provide fast ion transport and broad reaction interface of sulfur cathode,facilitating high capacity output and superior rate performance of Li-S batteries.As a result,Li-S batteries assembled with g-C3N4 can achieve high discharge capacity of 1200 mAh/g at 0.2 C and over 800 mAh/g is remained after 100 cycles with a coulombic efficiency more than 99.5%.When the C-rate rises to 5 C,the reversible capacity of Li-S batteries can still maintain at 607mAh/g.
基金supported by the Ministry of Science and Technology of China (973 Project No. 2018YFA0209102)the National Natural Science Foundation of China (11727807, 51725101, 51672050, 61790581)Science and Technology Commission of Shanghai Municipality (16DZ2260600)。
文摘Intrinsic electric-magnetic property and special nano-micro architecture of functional materials have a significant effect on its electromagnetic wave energy conversion,especially in the microwave absorption(MA) field.Herein,porous Ni1-xCox@Carbon composites derived from metal-organic framework(MOF)were successfully synthesized via solvothermal reaction and subsequent annealing treatments.Benefiting from the coordination,carbonized bimetallic Ni-Co-MOF maintained its initial skeleton and transformed into magnetic-carbon composites with tunable nano-micro structure.During the thermal decomposition,generated magnetic particles/clusters acted as a catalyst to promote the carbon sp^2 arrangement,forming special core-shell architecture.Therefore,pure Ni@C microspheres displayed strong MA behaviors than other Ni1-xCox@Carbon composites.Surprisingly,magnetic-dielectric Ni@C composites possessed the strongest reflection loss value-59.5 dB and the effective absorption frequency covered as wide as 4.7 GHz.Meanwhile,the MA capacity also can be boosted by adjusting the absorber content from 25% to 40%.Magnetic-dielectric synergy effect of MOF-derived Ni1-xCox@Carbon microspheres was confirmed by the off-axis electron holography technology making a thorough inquiry in the MA mechanism.
基金the financial support from the National Major Research and Development Plan(2018YFA0209402)the National Natural Science Foundation of China(22175077,21773093,22088101)the Natural Science Foundation of Guangdong Province(2021A1515012351)。
文摘Cathodic electrocatalytic reactions, such as hydrogen evolution and CO_(2)/N_(2) reduction, are the key processes that store intermittent electricity into stable chemical energy. Although a great progress has been made to boost activity and selectivity via elaborative catalyst design, the structure–property relationships have not been sufficiently understood in the context of surface reconfiguration under working conditions. Recent efforts devoted to tracking dynamic evolution of electrocatalysts using in-situ and/or operando techniques gave new insights into the real structure and working mechanism of active sites,and provided principles to design better catalysts. The achievement of cathodic electrocatalysts in this subject is herein summarized, focusing on the correlations between reconstructed surface and electrocatalytic performance. Briefly, the thermodynamics of reconstruction at cathodes is discussed at first, and then the representative progresses in H_(2) evolution and CO_(2)/N_(2) reduction are introduced in sequence to acquire insights into electrochemical processes on in-situ reconfigured surfaces or interfaces. Finally, a perspective is offered to guide future investigations. This review is anticipated to shed some new light on in-depth understanding cathodic electrocatalysis and exploiting prominent electrocatalysts.
基金This work was supported from the Ministry of Science and Technology(No.2016YFA0400900),the National Natural Science Foundation of China(No.21373191,No.21633006,and No.21303090),and the Fundamental Research Funds for the Central Universities(No.2030020028).
文摘The quest of exact and nonperturbative methods on quantum dissipation with nonlinear coupling environments remains in general a great challenge.In this review we present a comprehensive account on two approaches to the entangled system-and-environment dynamics,in the presence of linear-plus-quadratic coupling bath.One is the dissipaton-equation-ofmotion(DEOM)theory that has been extended recently to treat the nonlinear coupling environment.Another is the extended Fokker-Planck quantum master equation(FP-QME)approach that will be constructed in this work,based on its DEOM correspondence.We closely compare these two approaches,with the focus on the underlying quasi-particle picture,physical implications,and implementations.
基金the Fundamental Research Center of Artificial Photosynthesis(FRe CAP),financially supported by the National Natural Science Foundation of China(NSFC)(22088102)supported by the National Natural Science Foundation of China(21633009,21633010,21925206)+4 种基金the Cooperation Fund of Dalian National Laboratory for Clean Energy(DNL 201913)the International Partnership Program of Chinese Academy of Sciences(121421KYSB20190025)the Dalian Institute of Chemical Physics foundation of innovative research(DICP I201927)the Strategic Priority Research Program of Chinese Academy of Sciences(XDB17000000)the support from Liaoning Revitalization Talents Program(XLYC1807241)。
文摘Fabrication of heterostructure composed of one-dimensional(1D)and 2D semiconductors has inspired extensive interest in promoting photogenerated charge separation as well as performances of solar fuel production,but it is still challenging for(oxy)nitride photocatalysts due to their uncontrollable ammonia thermal preparative process.In this work,we report a synthesis on heterostructure of Ta_(3)N_(5)nanorods and CaTaO_(2)N(CTON)nanosheets(denoted as Ta_(3)N_(5)/CTON)by directly nitriding a 2D Dion-Jacobson(DJ)type of perovskite KCa_(2)Ta_(3)O_(10)(KCTO)precursor under the assistance of K_(2)CO_(3)flux.It is demonstrated that the 2D morphology of KCTO can be well inherited to get 2D CTON,and the Ta-rich(nonstoichiometric ratio of Ca:Ta compared to CTON)feature of the KCTO as well as the easy evaporation of K species results in the formation of 1D Ta_(3)N_(5)nanorods.Meanwhile,the formation of intermediate species K_(2)Ca_(2)Ta_(3)O_(9)N owning similar crystal lattice as Ta_(3)N_(5)was detected and deduced to be responsible for the generation of Ta_(3)N_(5)nanorods and observation of intimate interface between CTON and Ta_(3)N_(5).Benefitting from the formation of special 1D/2D type-II heterostructure,obviously promoted charge separation as well as photocatalytic water splitting performance can be obtained.Extended discussion demonstrates the generality of the hard-template preparative strategy developed here.To our knowledge,this should be the first fabrication of 1D/2D heterostructure for the(oxy)nitride semiconductors,and the developed hard-template strategy may provide an alternative way of fabricating heterostructures of other semiconductors prepared at high temperature.
基金financially supported by the National Natural Science Foundation of China(NSFC)(22088102)supported by the National Natural Science Foundation of China(21633009,21633010,21925206)+4 种基金the Cooperation Fund of Dalian National Laboratory for Clean Energy(DNL201913)International Partnership Program of Chinese Academy of Sciences(121421KYSB20190025)the DICP foundation of innovative research(DICPI201927)Strategic Priority Research Pro-gram of Chinese Academy of Sciences(XDB17000000)support from Liaoning Revitalization Talents Program(XLYC1807241)。
文摘The hybridization between the outmost s orbitals of metal(Bi^(3+),Sn^(2+),Pb^(2+),Ag^(+))and O 2 p orbitals has been widely employed to develop innovative semiconductors with upshift valence band as well as extended visible light response,but it is still challenging to obtain photocatalyst with absorption edge of above 550 nm.Here we report a novel Sn^(2+)-based oxyfluoride Sn_(2)TiNbO_6 F(STNOF)photocatalyst with a pyrochlore structure to exhibit an extended absorption edge to 650 nm and dual functionalities of both water reduction and oxidation.Density functional theory calculations suggest that the unprecedented broad-spectrum response of STNOF is mainly ascribed to the strengthened hybridization between O 2 p and Sn 5 s orbitals remarkably upshifting the valence band,which is caused by the distortion and compressive strain in the Sn06 F2 dodecahedron with second-order Jahn-Teller effect due to partial fluorine substitution.The structural distortion and compressive strain are experimentally confirmed by the Fourier-transformed extended X-ray absorption fine spectra.As probe tests of the photocatalytic functionalities,water reduction and oxidation half reactions were examined to see obvious H_(2)and O_(2)evolution under visible light irradiation.This work may provide an alternative strategy of developing extended visible light responsive semiconductors for promising solar energy conversion.
基金This work was supported by the Ministry of Science and Technology of China(No.2017YFA0204904 and No.2016YFA0400904)the National Natural Science Foundation of China(No.21633006),and Anhui Initiative in Quantum Information Technologies.
文摘In the pioneering work by R.A.Marcus,the solvation effect on electron transfer(ET)processes was investigated,giving rise to the celebrated nonadiabatic ET rate formula.In this work,on the basis of the thermodynamic solvation potentials analysis,we reexamine Marcus’formula with respect to the Rice-Ramsperger-Kassel-Marcus(RRKM)theory.Interestingly,the obtained RRKM analogue,which recovers the original Marcus’rate that is in a linear solvation scenario,is also applicable to the nonlinear solvation scenarios,where the multiple curve-crossing of solvation potentials exists.Parallelly,we revisit the corresponding Fermi’s golden rule results,with some critical comments against the RRKM analogue proposed in this work.For illustration,we consider the quadratic solvation scenarios,on the basis of physically well-supported descriptors.
基金the financial support from the National Natural Science Foundation of China(Grant nos.21506210 and 51361135701)
文摘Ultrathin free-standing electrospun carbon nanofiber web(ECNFW) used for the electrodes of the vanadium flow battery(VFB) has been fabricated by the electrospinning technique followed by the carbonization process in this study to reduce the ohmic polarization of the VFB. The microstructure, surface chemistry and electrochemical performance of ECNFW carbonized at various temperatures from 800 to 1400 °C have been investigated. The results show that ECNFW carbonized at 1100 °C exhibits the highest electrocatalytic activity toward the V;/V;redox reaction, and its electrocatalytic activity decreases along with the increase of carbonization temperature due to the drooping of the surface functional groups.While for the VO;/VO;redox couple, the electrocatalytic activity of ECNFW carbonized above 1100 °C barely changes as the carbonization temperature rises. It indicates that the surface functional groups could function as the reaction sites for the V;/V;redox couple, but have not any catalytic effect for the VO;/VO;redox couple. And the single cell test result suggests that ECNFW carbonized at 1100 °C is a promising material as the VFB electrode and the VFB with ECNFW electrodes obtains a super low internal resistance of 250 mΩ cm;.
基金supported by the Youth Innovation Promotion Association(no.2015147)CAS and National Program on Key Basic Research Project(973 Program,2012CB215500)+1 种基金the Outstanding Youngest Scientist FoundationChinese Academy of Sciences(CAS)
文摘Oxygen evolution reaction(OER) is one of the most important reactions in the energy storage devices such as metal–air batteries and unitized regenerative fuel cells(URFCs). However, the kinetically sluggishness of OER and the high prices as well as the scarcity of the most active precious metal electrocatalysts are the major bottleneck in these devices. Developing low-cost non-precious metal catalysts with high activity and stability for OER is highly desirable. A facile, in situ template method combining the dodecyl benzene sulfuric acid sodium(SDBS) assisted hydrothermal process with subsequent high-temperature treatment was developed to prepare porous Co3O4 with improved surface area and hierarchical porous structure as precious catalysts alternative for oxygen evolution reaction(OER). Due to the unique structure, the as-prepared catalyst shows higher electrocatalytic activity than Co3O4 prepared by traditional thermal-decomposition method(noted as Co3O4-T) and commercial IrO2 catalyst for OER in 0.1M KOH aqueous solution. Moreover, it displays improved stability than Co3O4-T. The results demonstrate a highly efficient, scalable, and low cost method for developing highly active and stable OER electrocatalysts in alkaline solutions.
基金supported by the Ministry of Education of Singapore under Tier 1 RG115/18 and RG4/20,and Tier 2 T2EP10120-0009.
文摘Amorphous alloys,also known as metallic glasses,are solid metallic materials having long-range disordered atomic structures.Compared to crystalline alloys,amorphous alloys not only have metallic characters,but also possess several distinct properties associated to the amorphous structure,such as isotropy,composition flexibility,unsaturated surface,etc.As a result,amorphous alloys offer a class of highly promising materials for catalyzing electrochemical reactions.In this minireview,the preparation,characterization and electrocatalytic performances of a variety of metallic amorphous alloy materials are summarized.The influences of the amorphous alloy structure on different electrochemical reactions are discussed.Finally,a summary on the advantages and challenges of amorphous alloys in electrocatalysis is provided,along with some perspectives about the future research directions.
基金financially supported in part by the National Key R&D Program of China(No.2017YFA0207301)the National Natural Science Foundation of China(Nos.21725102,U1832156,91961106,22075267,and 21950410514)+5 种基金CAS Key Research Program of Frontier Sciences(No.QYZDB-SSW-SLH018)CAS Interdisciplinary Innovation Team,Science and Technological Fund of Anhui Province for Outstanding Youth(No.2008085J05)Youth Innovation Promotion Association of CAS(No.2019444)Chinese Academy of Sciences Presidents International Fellowship Initiative(Nos.2019PC0114 and 2020T130627)China Postdoctoral Science Foundation(No.2019M652190)Young Elite Scientist Sponsorship Program by CAST,and DNL Cooperation Fund,CAS(No.DNL201922).
文摘Developing carbon-based electrocatalysts with excellent N2 adsorption and activation capability holds the key to achieve highly efficient nitrogen reduction reaction(NRR)for reaching its practical application.Here,we report a highly active electrocatalyst--metal-free pyrrolic-N dominated N,S co-doped carbon(pyrr-NSC)for NRR.Based on theoretical and experimental results,it is confirmed that the N and S-dopants practice a working-in-tandem mechanism on pyrr-NSC,where the N-dopants are utilized to create electropositive C sites for enhancing N2 adsorption and the S-dopants are employed to induce electron backdonation for facilitating N2 activation.The synergistic effect of the pyrrolic-N and S-dopants can also suppress the irritating hydrogen evolution reaction,further boosting the NRR performance.This work gives an indication that the combination of two different dopants on electrocatalyst can enhance NRR performance by working in the two tandem steps-the adsorption and activation of N2 molecules,providing a new strategy for NRR electrocatalyst design.
文摘Metal nanocatalysts have attracted widespread attention in heterogeneous catalysis for their remarkable catalytic performance.The electronic properties of metal nanoparticles govern the orbital hybridization and charge transfer between active metals and reactants;meanwhile,the local geometries of metal nanoparticles could also have a substantial impact on chemical bond breaking and bond making.
基金support from the National Key Research and Development Program of China(No.2019YFA0705400)the National Natural Science Foundation of China(Nos.21972121 and 22021001)the Fundamental Research Funds for the Central Universities(No.20720210017).
文摘Harvesting clean energy from water evaporation has been extensively investigated due to its sustainability.To achieve high efficiency,energy conversion materials should contain multiple features which are difficult to be simultaneously obtained from single-component materials.Here we use composite laminar membranes assembled by nanosheets of graphene oxide and mica,and find a sustained power density induced by water evaporation that is two orders of magnitude larger than that from membranes made by either of the components.The power output is attributed to selective proton transport driven by water evaporation through the interlayer nanochannels in the membranes.This process relies on the synergistic effects from negatively charged and hydrophilic mica surfaces that are important for proton selectivity and water transport,and the tunable electrical conductivity of graphene oxide that provides optimized internal resistance.The demonstrated composite membranes offer a strategy of enhancing power generation by combining the advantages from each of their components.
基金We gratefully acknowledge the financial support from the Ministry of Science and Technology of China (Grant Nos. 2016YFA0204100 and 2016YFA0200200), the Na- tional Natural Science Foundation of China (Grant Nos. 21573220 and 21621063), the Key Research Program of Frontier Sciences of the Chinese Academy of Sciences (Grant No. QYZDB-SSW- JSC020), and the Strategic Priority Research Program of the Chi- nese Academy of Sciences (Grant No. XDA09030100).
基金supported by the National Natural Science Foundation of China(No.91545124 and No.21750110437)supported by the Chinese Academy of Sciences President’s International Fellowship Initiative(No.2017PM0049)。