In order to obtain high-performance electromagnetic wave absorbers,the adjustment of structure and components is essential.Based on the above requirements,this system forms a three-dimensional frame structure consisti...In order to obtain high-performance electromagnetic wave absorbers,the adjustment of structure and components is essential.Based on the above requirements,this system forms a three-dimensional frame structure consisting of MXene and transition metal oxides(TMOs)through efficient electrostatic self-assembly.This three-dimensional network structure has rich heterojunction structures,which can cause a large amount of interface polarization and conduction losses in incident electromagnetic waves.Hollow structures cause multiple reflections and scattering of electromagnetic waves,which is also an important reason for further increasing electromagnetic wave losses.When the doping ratio is 1:1,the system has the best impedance matching,the maximum effective absorption bandwidth(EAB max)can reach 5.12 GHz at 1.7 mm,and the minimum reflection loss(RL_(min))is-50.30 dB at 1.8 mm.This provides a reference for the subsequent formation of 2D-MXene materials into 3D materials.展开更多
The bis(tributyltin) ester of succinic acid was synthesized by the reaction of disodium salt of succinic acid with tributyltin chloride in a molar ratio of 1:2. The crystal structure was determined by X-ray single-cry...The bis(tributyltin) ester of succinic acid was synthesized by the reaction of disodium salt of succinic acid with tributyltin chloride in a molar ratio of 1:2. The crystal structure was determined by X-ray single-crystal diffraction. It belongs to orthorhombic with space group Pccn, a = 20.949(3), b = 17.470(3), c = 20.345(3) Angstrom, V = 7446(2) Angstrom(3), Z = 8, D-c = 1.242 g/cm(3), mu = 1.365 mm(-1), F(000) = 2864, R = 0.0544 and wR = 0.1417. The tin atom is of five-coordination in a trigonal bipyramidal structure by bridging two carboxylate groups in different directions and the resulting structure which contains straight twist large ring channels along the axes of a, b and c is a three-dimensional framework polymer containing two different tin atoms.展开更多
Covalent organic frameworks(COFs) are a class of crystalline porous organic materials with variable structures and fascinating properties. The intrinsic low conductivity impedes their widely application in optoelectro...Covalent organic frameworks(COFs) are a class of crystalline porous organic materials with variable structures and fascinating properties. The intrinsic low conductivity impedes their widely application in optoelectronic. Iodine doping is an effective way to enhance the electrical conductivity of COFs. Here, a novel 3D imine COF with lvt topology is synthesized from two different pentacene derivatives with the same core in the form of structural complementarity. DDHP-COF is a highly crystalline material featuring high surface area of 1679 m^(2)/g and excellent thermal stability up to 490 ℃. Upon doping with iodine, the electrical conductivity can reach as high as 1.5×10^(-2)S/m which is significantly enhanced over 6 orders of magnitude compared with the pristine COF.展开更多
Metal-organic frameworks(MOFs),typically constructed with metallic nodes and organic linkers,have influenced the development of modular solid materials.Their adjustable molecular structure provides a remarkable variet...Metal-organic frameworks(MOFs),typically constructed with metallic nodes and organic linkers,have influenced the development of modular solid materials.Their adjustable molecular structure provides a remarkable variety of MOF-based solid-state structures towards diverse applications.However,the low conductivity of traditional MOFs extremely hinders their applications in electronic and electrochemical devices.The emerging conductive MOFs,generally possessing twodimensional layered structures,are endowed with both the structural merits of common MOFs and exceptional electronic/ionic conductivities.Besides,the selection and optimization of ligands and metal centers,as well as synthetic methods enormously affects the intrinsic conductivity of conductive MOFs.The distinctive crystal structures and superb conductivity promise their appealing applications in electrochemical energy-related fields.In the review,we mainly summarize representative crystal features,conducting mechanisms and recent advances in rational design and synthesis of conductive MOFs,along with their versatile applications as electrodes for electrochemical capacitors and rechargeable batteries,and as catalysts towards electrocatalysis.Finally,the involved challenges and future trends/prospects of the conductive MOFs for electrochemical energyrelated applications are further proposed.展开更多
Two-dimensional conductive metal-organic frameworks(2D c-MOFs),constructed by coordination between metal ions andπ-conjugated ligands,represent a unique class of materials that combine intrinsic porosity and electric...Two-dimensional conductive metal-organic frameworks(2D c-MOFs),constructed by coordination between metal ions andπ-conjugated ligands,represent a unique class of materials that combine intrinsic porosity and electrical conductivity.However,the contribution of metal nodes to the overall electrical properties remains unclear.In this work,we systematically investigate the role of metal centers on a series of six highly crystalline hexahydroxytriphenylene(HHTP)based c-MOFs,M-HHTP,which incorporate alkaline earth including magnesium and calcium,as well as transition metals including cobalt,nickel,copper,and zinc.Comprehensive structural characterizations reveal that while all M-HHTP frameworks adopt a general honeycomb lattice,however,subtle variations in stacking patterns and coordination environments are induced by different metal ions.Electrical measurements show a pronounced dependence of conductivity on the nature of the metal nodes,in which the conductivity differs by four orders of magnitude due to the difference in metal centers.Furthermore,non-contact terahertz spectroscopy combined with theoretical calculations suggests that in alkaline earth metal-based MOFs,charge transport may proceed via a through-space hopping mechanism between organic ligands.This study elucidates the critical role of metal centers in governing charge transport in M-HHTP MOFs and offers valuable guidance for the rational design of high-performance 2D conductive frameworks.展开更多
The open-framework iron phosphate IIIII21.543FeFe(PO) was hydrothermally synthesized and characterized by elemental analysis, IR, EPR, XPS and single crystal X-ray diffraction analysis. The title compound crystallized...The open-framework iron phosphate IIIII21.543FeFe(PO) was hydrothermally synthesized and characterized by elemental analysis, IR, EPR, XPS and single crystal X-ray diffraction analysis. The title compound crystallized in the triclinic, space group P1with a=0.64724(4) nm, b=0.79651(6) nm, c=0.94229(5) nm, =104.447(2)? =108.919(4)? =101.741(4)? V=0.42302(5) nm3, Z=1 and R1 (wR2)=0.0307 (0.0793). Crystal data were collected on a Rigaku R-AXIS RAPID IP diffractometer with Mo K?(=0.071073 nm) at 293(2) K in the range of 2.43埃迹?7.46? The structure of 1 consists of 19 non-hydrogen atoms including three and a half crystallographically in-dependent Fe and three P atoms. Fe(1) connects its symmetrical Fe(1A) through bridging oxygen forming a dimer and the dimers are connected by Fe(4) forming an infinite staircase-like chain. Fe(2) and Fe(3) connect the infinite chains into a layer with bridging oxygen. Layers are interconnected via Fe(4) forming the six-membered and eight-membered channel systems.展开更多
Developing laminar composite solid electrolyte with ultrathin thickness and continuous conduction channels in vertical direction holds great promise for all-solid-state lithium batteries.Herein,a thin,laminar solid el...Developing laminar composite solid electrolyte with ultrathin thickness and continuous conduction channels in vertical direction holds great promise for all-solid-state lithium batteries.Herein,a thin,laminar solid electrolyte is synthesized by filtrating–NH 2 functionalized metal-organic framework nanosheets and then being threaded with poly(ethylene oxide)chains induced by the hydrogen-bonding interaction from–NH_(2) groups.It is demonstrated that the threaded poly(ethylene oxide)chains lock the adjacent metal-organic framework nanosheets,giving highly enhanced structural stability(Young’s modulus,1.3 GPa)to 7.5-μm-thick laminar composite solid electrolyte.Importantly,these poly(ethylene oxide)chains with stretching structure serve as continuous conduction pathways along the chains in pores.It makes the non-conduction laminar metal-organic framework electrolyte highly conductive:3.97×10^(−5) S cm^(−1) at 25℃,which is even over 25 times higher than that of pure poly(ethylene oxide)electrolyte.The assembled lithium cell,thus,acquires superior cycling stability,initial discharge capacity(148 mAh g^(−1) at 0.5 C and 60℃),and retention(94% after 150 cycles).Besides,the pore size of nanosheet is tailored(24.5–40.9˚A)to evaluate the mechanisms of chain conformation and ion transport in confined space.It shows that the confined pore only with proper size could facilitate the stretching of poly(ethylene oxide)chains,and meanwhile inhibit their disorder degree.Specifically,the pore size of 33.8˚A shows optimized confinement effect with trans-poly(ethylene oxide)and cis-poly(ethylene oxide)conformation,which offers great significance in ion conduction.Our design of poly(ethylene oxide)-threaded architecture provides a platform and paves a way to the rational design of next-generation high-performance porous electrolytes.展开更多
Composite Li metal anodes based on three-dimensional(3D) porous frameworks have been considered as an effective material for achieving stable Li metal batteries with high energy density.However,uneven Li deposition be...Composite Li metal anodes based on three-dimensional(3D) porous frameworks have been considered as an effective material for achieving stable Li metal batteries with high energy density.However,uneven Li deposition behavior still occurs at the top of 3D frameworks owing to the local accumulation of Li ions.To promote uniform Li deposition without top dendrite growth,herein,a layered multifunctional framework based on oxidation-treated polyacrylonitrile(OPAN) and metal-organic framework(MOF) derivatives was proposed for rationally regulating the distribution of Li ions flux,nucleation sites,and electrical conductivity.Profiting from these merits,the OPAN/carbon nano fiber-MOF(CMOF) composite framework demonstrated a reversible Li plating/stripping behavior for 500 cycles with a stable Coulombic efficiency of around 99.0% at the current density of 2 mA/cm~2.Besides,such a Li composite anode exhibited a superior cycle lifespan of over 1300 h under a low polarized voltage of 18 mV in symmetrical cells.When the Li composite anode was paired with LiFePO_(4)(LFP) cathode,the obtained full cell exhibited a stable cycling over 500 cycles.Moreover,the COMSOL Multiphysics simulation was conducted to reveal the effects on homogeneous Li ions distribution derived from the above-mentioned OPAN/CMOF framework and electrical insulation/conduction design.These electrochemical and simulated results shed light on the difficulties of designing stable and safe Li metal anode via optimizing the 3D frameworks.展开更多
NiFe composites have been regarded as promising candidates to replace commercial noble-based electrocatalysts for the oxygen evolution reaction(OER).However,their practical applications still suffer from poor conducti...NiFe composites have been regarded as promising candidates to replace commercial noble-based electrocatalysts for the oxygen evolution reaction(OER).However,their practical applications still suffer from poor conductivity,limited activity,durability.To address these issues,herein,by utilizing three-dimensional covalent organic framework(3D-COF)with porous confined structures and abundant coordinate N sites as the precursor,the partially oxidized Ni_(3)Fe nanoalloys wrapped by Ndoped carbon(N-C)layers are constructed via simple pyrolysis and subsequent oxidization.Benefiting from the 3D curved hierarchical structure,high-conductivity of Ni_(3)Fe and N-C layers,well-distributed active sites,the as-synthesized O-Ni_(3)Fe-NC catalyst demonstrates excellent activity and durability for catalyzing OER.Experimental and theoretical analyses disclose that both high-temperature oxidization and the OER process greatly promote the formation and exposure of the Ni(Fe)OOH active species as well as lower charge transfer resistance,inducing its optimized OER activity.The robust graphitized N-C layers with superior conductivity and their couplings with oxidized Ni_(3)Fe nanoalloys are beneficial for stabilizing catalytic centers,thereby imparting O-Ni_(3)Fe-N-C with such outstanding stability.This work not only provides a rational guidance for enriching and stabilizing high-activity catalytic sites towards OER but also offers more insights into the structural evolution of NiFe-based OER catalysts.展开更多
Although metal–organic frameworks have been heavily tested as the anode materials for lithium-ion batteries(LIBs),the poorer conductivity,easy collapse of frameworks,and serious volume expansion limit their further a...Although metal–organic frameworks have been heavily tested as the anode materials for lithium-ion batteries(LIBs),the poorer conductivity,easy collapse of frameworks,and serious volume expansion limit their further application in LIBs.Herein,we report a facile approach to obtain MXene-encapsulated porous Ni-naphthalene dicarboxylic acid(Ni-NDC)nanosheets by hybridizing ultrathin Ti_(3)C_(2)MXene and three-dimensional(3D)Ni-NDC nanosheet aggregates.In the structure of Ni-NDC/MXene hybrids,the interlayer hydrogen-bond interaction between Ni-NDC and MXene can effectively increase the interlayer spacing and further inhibit the oxidation of pure MXene.Hence,the introduction of MXene(a conductive matrix)could further improve the conductivity of Ni-NDC,avoid self-agglomeration,and buffer the volume expansion of Ni-NDC nanosheets.Benefiting from the synergistic effects between Ni-NDC and MXene,Ni-NDC/MXene hybrid electrode exhibits a reversible discharge capacity(579.8 mA∙h∙g^(−1)at 100 mA∙g^(−1)after 100 cycles)and good long-term cycling performance(310 mA∙h∙g^(−1)at 1 A∙g^(−1)after 500 cycles).展开更多
At present,commercial Li-ion batteries are hardly to satisfy the growing demand for high energy density,for this purpose,lithium metal batteries have attracted worldwide attention in recent years.However,its practical...At present,commercial Li-ion batteries are hardly to satisfy the growing demand for high energy density,for this purpose,lithium metal batteries have attracted worldwide attention in recent years.However,its practical applications are hindered by the formation of Li dendrites and volume effect during Li plating/stripping process,which leads to a lot of safety hazards.Herein,we first employed MOF-derived V_(2)O_(5) nanoparticles to decorate the carbon fiber cloth(CFC)backbone to acquire a lithiophilic 3D porous conductive framework(CFC@V_(2)O_(5)).Subsequently,the CFC@V_(2)O_(5) skeleton was permeated with molten Li to prepare CFC@V_(2)O_(5)@Li composite anode.The CFC@V_(2)O_(5)@Li composite anode can be stably cycled for more than 1650 h at high current density(5 mA·cm^(-2))and areal capacity(5 mA·h·cm^(–2)).The prepared full cell can initially maintain a high capacity of about 143 mA·h·g^(-1) even at a high current density of 5 C,and can still maintain 114 mA·h·g^(-1) after 1000 cycles.展开更多
基金supported by the National Natural Science Foundation of China(Nos.51407134,52002196)Natural Science Foundation of Shandong Province(Nos.ZR2019YQ24,ZR2020QF084)+1 种基金Taishan Scholars and Young Experts Program of Shandong Province(No.tsqn202103057)the Qingchuang Talents Induction Program of Shandong Higher Education Institution(Research and Innovation Team of Structural-Functional Polymer Composites)and Special Financial of Shandong Province(Structural Design of High-efficiency Electromagnetic Wave-absorbing Composite Materials and Construction of Shandong Provincial Talent Teams(No.37000022P990304116449)).
文摘In order to obtain high-performance electromagnetic wave absorbers,the adjustment of structure and components is essential.Based on the above requirements,this system forms a three-dimensional frame structure consisting of MXene and transition metal oxides(TMOs)through efficient electrostatic self-assembly.This three-dimensional network structure has rich heterojunction structures,which can cause a large amount of interface polarization and conduction losses in incident electromagnetic waves.Hollow structures cause multiple reflections and scattering of electromagnetic waves,which is also an important reason for further increasing electromagnetic wave losses.When the doping ratio is 1:1,the system has the best impedance matching,the maximum effective absorption bandwidth(EAB max)can reach 5.12 GHz at 1.7 mm,and the minimum reflection loss(RL_(min))is-50.30 dB at 1.8 mm.This provides a reference for the subsequent formation of 2D-MXene materials into 3D materials.
基金the National Natural Science Foundation of China (No. 20271025)the Natural Science Foundation of Shandong province (No. Z2001B02)the State Key Laboratory of Crystal Materials,Shandong University
文摘The bis(tributyltin) ester of succinic acid was synthesized by the reaction of disodium salt of succinic acid with tributyltin chloride in a molar ratio of 1:2. The crystal structure was determined by X-ray single-crystal diffraction. It belongs to orthorhombic with space group Pccn, a = 20.949(3), b = 17.470(3), c = 20.345(3) Angstrom, V = 7446(2) Angstrom(3), Z = 8, D-c = 1.242 g/cm(3), mu = 1.365 mm(-1), F(000) = 2864, R = 0.0544 and wR = 0.1417. The tin atom is of five-coordination in a trigonal bipyramidal structure by bridging two carboxylate groups in different directions and the resulting structure which contains straight twist large ring channels along the axes of a, b and c is a three-dimensional framework polymer containing two different tin atoms.
基金financially supported by the National Natural Science Foundation of China (Nos. 51973153, 22001191)。
文摘Covalent organic frameworks(COFs) are a class of crystalline porous organic materials with variable structures and fascinating properties. The intrinsic low conductivity impedes their widely application in optoelectronic. Iodine doping is an effective way to enhance the electrical conductivity of COFs. Here, a novel 3D imine COF with lvt topology is synthesized from two different pentacene derivatives with the same core in the form of structural complementarity. DDHP-COF is a highly crystalline material featuring high surface area of 1679 m^(2)/g and excellent thermal stability up to 490 ℃. Upon doping with iodine, the electrical conductivity can reach as high as 1.5×10^(-2)S/m which is significantly enhanced over 6 orders of magnitude compared with the pristine COF.
基金The authors acknowledge the financial support from National Natural Science Foundation of China(No.51772127,51772131,and 51802119)Taishan Scholars(No.ts201712050)+2 种基金Major Program of Shandong Province Natural Science Foundation(ZR2018ZB0317)Natural Science Doctoral Foundation of Shandong Province(ZR2018BEM018,ZR2019BB057)Collaborative Innovation Center of Technology and Equipment for Biological Diagnosis and Therapy in Universities of Shandong.
文摘Metal-organic frameworks(MOFs),typically constructed with metallic nodes and organic linkers,have influenced the development of modular solid materials.Their adjustable molecular structure provides a remarkable variety of MOF-based solid-state structures towards diverse applications.However,the low conductivity of traditional MOFs extremely hinders their applications in electronic and electrochemical devices.The emerging conductive MOFs,generally possessing twodimensional layered structures,are endowed with both the structural merits of common MOFs and exceptional electronic/ionic conductivities.Besides,the selection and optimization of ligands and metal centers,as well as synthetic methods enormously affects the intrinsic conductivity of conductive MOFs.The distinctive crystal structures and superb conductivity promise their appealing applications in electrochemical energy-related fields.In the review,we mainly summarize representative crystal features,conducting mechanisms and recent advances in rational design and synthesis of conductive MOFs,along with their versatile applications as electrodes for electrochemical capacitors and rechargeable batteries,and as catalysts towards electrocatalysis.Finally,the involved challenges and future trends/prospects of the conductive MOFs for electrochemical energyrelated applications are further proposed.
基金supported by the National Natural Science Foundation of China(22305238,22475203)Anhui Provincial Natural Science Foundation(2308085MB35)the Innovation Program for Quantum Science and Technology(2021zD0303303).
文摘Two-dimensional conductive metal-organic frameworks(2D c-MOFs),constructed by coordination between metal ions andπ-conjugated ligands,represent a unique class of materials that combine intrinsic porosity and electrical conductivity.However,the contribution of metal nodes to the overall electrical properties remains unclear.In this work,we systematically investigate the role of metal centers on a series of six highly crystalline hexahydroxytriphenylene(HHTP)based c-MOFs,M-HHTP,which incorporate alkaline earth including magnesium and calcium,as well as transition metals including cobalt,nickel,copper,and zinc.Comprehensive structural characterizations reveal that while all M-HHTP frameworks adopt a general honeycomb lattice,however,subtle variations in stacking patterns and coordination environments are induced by different metal ions.Electrical measurements show a pronounced dependence of conductivity on the nature of the metal nodes,in which the conductivity differs by four orders of magnitude due to the difference in metal centers.Furthermore,non-contact terahertz spectroscopy combined with theoretical calculations suggests that in alkaline earth metal-based MOFs,charge transport may proceed via a through-space hopping mechanism between organic ligands.This study elucidates the critical role of metal centers in governing charge transport in M-HHTP MOFs and offers valuable guidance for the rational design of high-performance 2D conductive frameworks.
基金the National Natural Science Foundation of China (No. 20171010).
文摘The open-framework iron phosphate IIIII21.543FeFe(PO) was hydrothermally synthesized and characterized by elemental analysis, IR, EPR, XPS and single crystal X-ray diffraction analysis. The title compound crystallized in the triclinic, space group P1with a=0.64724(4) nm, b=0.79651(6) nm, c=0.94229(5) nm, =104.447(2)? =108.919(4)? =101.741(4)? V=0.42302(5) nm3, Z=1 and R1 (wR2)=0.0307 (0.0793). Crystal data were collected on a Rigaku R-AXIS RAPID IP diffractometer with Mo K?(=0.071073 nm) at 293(2) K in the range of 2.43埃迹?7.46? The structure of 1 consists of 19 non-hydrogen atoms including three and a half crystallographically in-dependent Fe and three P atoms. Fe(1) connects its symmetrical Fe(1A) through bridging oxygen forming a dimer and the dimers are connected by Fe(4) forming an infinite staircase-like chain. Fe(2) and Fe(3) connect the infinite chains into a layer with bridging oxygen. Layers are interconnected via Fe(4) forming the six-membered and eight-membered channel systems.
基金The authors would like to acknowledge the financial support from National Nat-ural Science Foundation of China (U2004199)Excellent Youth Foundation of Henan Province (202300410373)+2 种基金China Postdoctoral Science Foundation (2021T140615 and 2020M672281)Natural Science Foundation of Henan Province (212300410285)Young Talent Support Project of Henan Province(2021HYTP028).
文摘Developing laminar composite solid electrolyte with ultrathin thickness and continuous conduction channels in vertical direction holds great promise for all-solid-state lithium batteries.Herein,a thin,laminar solid electrolyte is synthesized by filtrating–NH 2 functionalized metal-organic framework nanosheets and then being threaded with poly(ethylene oxide)chains induced by the hydrogen-bonding interaction from–NH_(2) groups.It is demonstrated that the threaded poly(ethylene oxide)chains lock the adjacent metal-organic framework nanosheets,giving highly enhanced structural stability(Young’s modulus,1.3 GPa)to 7.5-μm-thick laminar composite solid electrolyte.Importantly,these poly(ethylene oxide)chains with stretching structure serve as continuous conduction pathways along the chains in pores.It makes the non-conduction laminar metal-organic framework electrolyte highly conductive:3.97×10^(−5) S cm^(−1) at 25℃,which is even over 25 times higher than that of pure poly(ethylene oxide)electrolyte.The assembled lithium cell,thus,acquires superior cycling stability,initial discharge capacity(148 mAh g^(−1) at 0.5 C and 60℃),and retention(94% after 150 cycles).Besides,the pore size of nanosheet is tailored(24.5–40.9˚A)to evaluate the mechanisms of chain conformation and ion transport in confined space.It shows that the confined pore only with proper size could facilitate the stretching of poly(ethylene oxide)chains,and meanwhile inhibit their disorder degree.Specifically,the pore size of 33.8˚A shows optimized confinement effect with trans-poly(ethylene oxide)and cis-poly(ethylene oxide)conformation,which offers great significance in ion conduction.Our design of poly(ethylene oxide)-threaded architecture provides a platform and paves a way to the rational design of next-generation high-performance porous electrolytes.
基金supported by the National Natural Science Foundation of China (52302292, 52302058, 52302085)the China Postdoctoral Science Foundation (2021M702225)+1 种基金the Anhui Province University Natural Science Research Project (2023AH030093, 2023AH040301)the Startup Research Fund of Chaohu University (KYQD-2023005, KYQD-2023051)。
文摘Composite Li metal anodes based on three-dimensional(3D) porous frameworks have been considered as an effective material for achieving stable Li metal batteries with high energy density.However,uneven Li deposition behavior still occurs at the top of 3D frameworks owing to the local accumulation of Li ions.To promote uniform Li deposition without top dendrite growth,herein,a layered multifunctional framework based on oxidation-treated polyacrylonitrile(OPAN) and metal-organic framework(MOF) derivatives was proposed for rationally regulating the distribution of Li ions flux,nucleation sites,and electrical conductivity.Profiting from these merits,the OPAN/carbon nano fiber-MOF(CMOF) composite framework demonstrated a reversible Li plating/stripping behavior for 500 cycles with a stable Coulombic efficiency of around 99.0% at the current density of 2 mA/cm~2.Besides,such a Li composite anode exhibited a superior cycle lifespan of over 1300 h under a low polarized voltage of 18 mV in symmetrical cells.When the Li composite anode was paired with LiFePO_(4)(LFP) cathode,the obtained full cell exhibited a stable cycling over 500 cycles.Moreover,the COMSOL Multiphysics simulation was conducted to reveal the effects on homogeneous Li ions distribution derived from the above-mentioned OPAN/CMOF framework and electrical insulation/conduction design.These electrochemical and simulated results shed light on the difficulties of designing stable and safe Li metal anode via optimizing the 3D frameworks.
基金supported by the National Natural Science Foundation of China(Nos.52131003,52122007,52200076)the Specific Research Fellowship of Chinese Academy of Sciences(No.E329620101)the Natural Science Foundation of Chongqing(No.cstb2022nscq-bhx0035)~~。
基金the National Natural Science Foundation of China(Nos.22075062 and 21871167)and the Volkswagen Foundation(Freigeist Fellowship)。
文摘NiFe composites have been regarded as promising candidates to replace commercial noble-based electrocatalysts for the oxygen evolution reaction(OER).However,their practical applications still suffer from poor conductivity,limited activity,durability.To address these issues,herein,by utilizing three-dimensional covalent organic framework(3D-COF)with porous confined structures and abundant coordinate N sites as the precursor,the partially oxidized Ni_(3)Fe nanoalloys wrapped by Ndoped carbon(N-C)layers are constructed via simple pyrolysis and subsequent oxidization.Benefiting from the 3D curved hierarchical structure,high-conductivity of Ni_(3)Fe and N-C layers,well-distributed active sites,the as-synthesized O-Ni_(3)Fe-NC catalyst demonstrates excellent activity and durability for catalyzing OER.Experimental and theoretical analyses disclose that both high-temperature oxidization and the OER process greatly promote the formation and exposure of the Ni(Fe)OOH active species as well as lower charge transfer resistance,inducing its optimized OER activity.The robust graphitized N-C layers with superior conductivity and their couplings with oxidized Ni_(3)Fe nanoalloys are beneficial for stabilizing catalytic centers,thereby imparting O-Ni_(3)Fe-N-C with such outstanding stability.This work not only provides a rational guidance for enriching and stabilizing high-activity catalytic sites towards OER but also offers more insights into the structural evolution of NiFe-based OER catalysts.
基金supported by the National Natural Science Foundation of China(Nos.62174085 and 21805136)the Program for Young Changjiang Scholars of the Ministry of Education,the Jiangsu Specially-Appointed Professors Program,the Top-notch Academic Programs Project of Jiangsu Higher Education Institutions(TAPP),the Natural Science Foundation of Jiangsu Province(No.BK20200044)the Startup Foundation for Introducing Talent of NUIST(No.2021r091).
文摘Although metal–organic frameworks have been heavily tested as the anode materials for lithium-ion batteries(LIBs),the poorer conductivity,easy collapse of frameworks,and serious volume expansion limit their further application in LIBs.Herein,we report a facile approach to obtain MXene-encapsulated porous Ni-naphthalene dicarboxylic acid(Ni-NDC)nanosheets by hybridizing ultrathin Ti_(3)C_(2)MXene and three-dimensional(3D)Ni-NDC nanosheet aggregates.In the structure of Ni-NDC/MXene hybrids,the interlayer hydrogen-bond interaction between Ni-NDC and MXene can effectively increase the interlayer spacing and further inhibit the oxidation of pure MXene.Hence,the introduction of MXene(a conductive matrix)could further improve the conductivity of Ni-NDC,avoid self-agglomeration,and buffer the volume expansion of Ni-NDC nanosheets.Benefiting from the synergistic effects between Ni-NDC and MXene,Ni-NDC/MXene hybrid electrode exhibits a reversible discharge capacity(579.8 mA∙h∙g^(−1)at 100 mA∙g^(−1)after 100 cycles)and good long-term cycling performance(310 mA∙h∙g^(−1)at 1 A∙g^(−1)after 500 cycles).
基金supported by National Natural Science Foundation of China(21701083).
文摘At present,commercial Li-ion batteries are hardly to satisfy the growing demand for high energy density,for this purpose,lithium metal batteries have attracted worldwide attention in recent years.However,its practical applications are hindered by the formation of Li dendrites and volume effect during Li plating/stripping process,which leads to a lot of safety hazards.Herein,we first employed MOF-derived V_(2)O_(5) nanoparticles to decorate the carbon fiber cloth(CFC)backbone to acquire a lithiophilic 3D porous conductive framework(CFC@V_(2)O_(5)).Subsequently,the CFC@V_(2)O_(5) skeleton was permeated with molten Li to prepare CFC@V_(2)O_(5)@Li composite anode.The CFC@V_(2)O_(5)@Li composite anode can be stably cycled for more than 1650 h at high current density(5 mA·cm^(-2))and areal capacity(5 mA·h·cm^(–2)).The prepared full cell can initially maintain a high capacity of about 143 mA·h·g^(-1) even at a high current density of 5 C,and can still maintain 114 mA·h·g^(-1) after 1000 cycles.
