Topochemical fluorination introduces significant structural distortions and emerging properties in perovskite oxides via substituting oxygen with fluorine.However,the rapid fluorination process and the similarity betw...Topochemical fluorination introduces significant structural distortions and emerging properties in perovskite oxides via substituting oxygen with fluorine.However,the rapid fluorination process and the similarity between F and O render the O/F site occupation and local lattice evolution during fluorination unclear.Here we investigated the atomic-scale O/F exchange in La2CoO4and quantified the lattice distortion of three ordered structures:La_(2)CoO_(3.5)F,La_(2)CoO_(3)F_(2),and La_(2)CoO_(2.5)F_(3)by utilizing aberration-corrected electron microscopy.Atomic-resolved elemental mapping provides direct evidence for the O/F occupancy in interstitial and apical sites.We revealed that apical F ions induce significant octahedral tilting from 178°to 165°,linearly proportional to the occupancy rate;and cause the obvious change in the fine structure O K edge,meanwhile apical O is exchanged into interstitial sites.The strong octahedral tilt leads to the in-plane elongation of the[CoO_(4)F_(2)]octahedra.These findings elucidate the atomic-scale mechanisms of the entire fluorination process and highlight the significant role of F in tuning the octahedral tilt of functional oxides.展开更多
The underlying spin-related mechanism remains unclear,and the rational manipulation of spin states is challenging due to various spin configurations under different coordination conditions.Therefore,it is urgent to st...The underlying spin-related mechanism remains unclear,and the rational manipulation of spin states is challenging due to various spin configurations under different coordination conditions.Therefore,it is urgent to study spin-dependent oxygen evolution reaction(OER)performance through a controllable method.Herein,we adopt a topochemical reaction method to synthesize a series of selenides with eg occupancies ranging from 1.67 to 1.37.The process begins with monoclinic-CoSeO_(3),featuring a distinct laminar structure and Co-O6 coordination.The topochemical reaction induces significant changes in the crystal field's intensity,leading to spin state transitions.These transitions are driven by topological changes from a Co-O-Se-O-Co to a Co-Se-Co configuration,strengthening the crystalline field and reducing eg orbital occupancy.This reconfiguration of spin states shifts the rate-determining step from desorption to adsorption for both OER and the hydrogen evolution reaction(HER),reducing the potential-determined step barrier and enhancing overall catalytic efficiency.As a result,the synthesized cobalt selenide exhibits significantly enhanced adsorption capabilities.The material demonstrates impressive overpotentials of 35 mV for HER,250 mV for OER,and 270 mV for overall water splitting,indicating superior catalytic activity and efficiency.Additionally,a negative relation between eg filling and OER catalytic performance confirms the spin-dependent nature of OER.Our findings provide crucial insights into the role of spin state transitions in catalytic performance.展开更多
Based on block copolymer assisted topochemical polymerization,a new strategy for facilely producing robust nanoporous membranes with controlled incorporation of functional groups onto nanopores is developed.As exempli...Based on block copolymer assisted topochemical polymerization,a new strategy for facilely producing robust nanoporous membranes with controlled incorporation of functional groups onto nanopores is developed.As exemplified by preparing nanoporous polypyrrole decorated with amino acids,this strategy exhibits a high degree of freedom for tailoring the surface functionality in the created pores.展开更多
The diphenyldiacetylene （DPDA） and the corresponding polymers has become one of hot research topics in the field of functional materials, due to its highly π-conjugated system and outstanding electrochemical proper...The diphenyldiacetylene （DPDA） and the corresponding polymers has become one of hot research topics in the field of functional materials, due to its highly π-conjugated system and outstanding electrochemical properties. Compared with routine polydiacetylenes, polydiphenyldiacetylene （PDPDA） has wider π-extension within the whole polymer structure and a larger internlolecular stacking tendency. Since the preorganization of monomers is essential for the topochemical polymerization, we here introduce several self-assembled methods and external-templated methods for the proper alignment of DPDA. From the perspective of morphology, the monomer structures and external templates are two of the important factors towards polymerization. Based on its structure, PDPDA can become a promising intelligent material for various optoelectical applications, and specifically we summarize the application of PDPDA as an effective phtocatalyst in organic pollutants degradation展开更多
Topochemical transformation has emerged as a promising method for fabricating two-dimensional (2D) materials with precise control over their composition and morphology. However, the large-scale synthesis of ultrathin ...Topochemical transformation has emerged as a promising method for fabricating two-dimensional (2D) materials with precise control over their composition and morphology. However, the large-scale synthesis of ultrathin 2D materials with controllable thickness remains a tremendous challenge. Herein, we adopt an efficient topochemical synthesis strategy, employing a confined reaction space to fabricate ultrathin 2D Sn_(4)P_(3) nanosheets in large-scale. By carefully adjusting the rolling number during the processing of Sn/Al foils, we have successfully fabricated Sn_(4)P_(3) nanosheets with varied layer thicknesses, achieving a remarkable minimum thickness of two layers (~ 2.2 nm). Remarkably, the bilayer Sn_(4)P_(3) nanosheets display an exceptional initial capacity of 1088 mAh·g^(−1), nearing the theoretical value of 1230 mAh·g^(−1). Furthermore, we reveal their high-rate property as well as outstanding cyclic stability, maintaining capacity without fading more than 3000 cycles. By precisely controlling the layer thickness and ensuring nanoscale uniformity, we enhance the lithium cycling performance of Sn_(4)P_(3), marking a significant advancement in developing high-performance energy storage systems.展开更多
Silicon is the most promising anode material for the next generation high- performance lithium ion batteries. However, its commercial application is hindered by its poor performance due to the huge volume change durin...Silicon is the most promising anode material for the next generation high- performance lithium ion batteries. However, its commercial application is hindered by its poor performance due to the huge volume change during cycling. Although two-dimensional silicon-based materials show significantly improved performance, flexible synthesis of such materials is still a challenge. In this work, silicon-based nanosheets with a multilayer structure are synthesized for the first time by a topochemical reaction. The morphology and oxidation state of these nanosheets can be controlled by appropriate choice of reaction media and oxidants. Benefiting from the hierarchical structure and ultrathin size, when the silicon-based nanosheets are employed as anodes they exhibit a charge （delithiation） capacity of 800 mAh/g after 50 cycles with a maximum coulombic efficiency of 99.4% and good rate performance （647 mAh/g at 1 A/g）. This work demonstrates a novel method for preparing nanosheets not only for lithium ion batteries but also having various potential applications in other fields, such as catalysts, electronics and photonics.展开更多
Topochemical polymerization of molecular crystals into porous materials is of significance due to their promising applications in the field of adsorption and catalysis,yet rarely reported due to the synthesis difficul...Topochemical polymerization of molecular crystals into porous materials is of significance due to their promising applications in the field of adsorption and catalysis,yet rarely reported due to the synthesis difficulty.Herein,a hydrogen-bonded organic framework(HOF-45)has been fabricated by the crystallization of a cage-like building block containing three alkynyl groups.It exhibits almost mesoporous structure demonstrated by single crystal X-ray diffraction study.Light-driven topochemical polymerization of HOF-45 with ethanedithiol covalently links alkynyl groups in HOF-45,generating a hydrogen-bond and covalentbond cross-linked material(HOF-45C).In contrast to HOF-45,cross-linked HOF-45C retains the crystalline nature and displays improved solution resistence according to the powder X-ray diffraction data.In particular,HOF-45C is able to support the growth of ultrafine palladium nanoparticles with the average size of ca.1.9 nm for rapidly promoting the degradation of nitrophenol,methyl orange,and congo red with the help of NaBH_(4)as well as Suzuki-Miyaura coupling reaction.This work inputs a new idea on the HOFs application in preparing covalent-linked porous organic materials.展开更多
The intricate correlation between multiple degrees of freedom and physical properties is a fascinating area in solid state chemistry and condensed matter physics.Here,we report a quantum-magnetic system BaNi_(2)V_(2)O...The intricate correlation between multiple degrees of freedom and physical properties is a fascinating area in solid state chemistry and condensed matter physics.Here,we report a quantum-magnetic system BaNi_(2)V_(2)O_(8)(BNVO),in which the spin correlation was modulated by unusual oxidation state,leading to different magnetic behavior.The BNVO was modified with topochemical reduction(TR)to yield TR-BNVO with partially reduced valance state of Ni^(+)in the two-dimensional NiO_(6)-honeycomb lattice.Accordingly,the antiferromagnetic order is suppressed by the introduction of locally interposed Ni^(+)and oxygen vacancies,resulting in a ferromagnetic ground state with the transition temperature up to 710 K.A positive magnetoresistance(7.5%)was observed in the TR-BNVO at 40 K under 7 T.These findings show that topological reduction is a powerful approach to engineer low-dimensional materials and accelerate the discovery of new quantum magnetism.展开更多
Topochemical ion-exchange reactions between solid micro- and nanostructured metal chalcogenides and aqueous salt solutions are generally used for formation of composite structures based on initial metal chalcogenides ...Topochemical ion-exchange reactions between solid micro- and nanostructured metal chalcogenides and aqueous salt solutions are generally used for formation of composite structures based on initial metal chalcogenides and products of their ion-exchange transformation. However, ion exchange has promises as a route to obtaining both composites and solid solutions based on the initial and the end chalcogenide phases. With the help of the ion-exchange technique, single-phase films of Phi xSnxSe substitutional solid solutions with a tin content up to -2 at.%, which are promising for mid- and long-wavelength infrared radiation （IR） optoelectronics, have been obtained at the interface between PbSe poly- crystalline thin films and SnCl2 aqueous solutions containing sodium citrate. It has been shown that the pH value and temperature of the reaction system play an important role in the ion-exchange process. Incubation of lead selenide （PbSe） films in a tin（II） salt aqueous solution also leads to their modification with oxygen-containing tin compounds to a depth of-3 nm. Differences in the film structure, such as changes in the coherent scattering region sizes and orientation of crystallites along the [220] direction, which arise during the contact with citrate-containing SnCl2 solutions, have also been revealed. For the first time, an idea of the existence of a relatively wide reaction zone of an intragranular topochemical ion-exchange reaction in an aqueous solution, within which substitutional solid solutions can form in micro- and nanostructured systems, has been set forth.展开更多
A novel and simple strategy of morphology-controlled Sr Ti O3（ST） micro-scale particle synthesis by the flux method is reported. Systematic experiments are designed to realize the tunable morphologies of the particl...A novel and simple strategy of morphology-controlled Sr Ti O3（ST） micro-scale particle synthesis by the flux method is reported. Systematic experiments are designed to realize the tunable morphologies of the particles when the flux salt,sintering process, and the precursors are changed. The ST plates can be synthesized by plate-like Bi4Ti3O12（BIT） precursors in Na Cl flux. However, the as-synthesized Bi4Ti3O12 grains transform into reticular particles and finally into rods at higher temperature in Na Cl and KCl compounds. Besides, cubic ST particles are also prepared using different precursors as a comparative experiment. This study provides a strategy for further investigations in designing the morphology-controlled particles and efficient anisotropic materials of perovskite structure such as ferroelectric and photocatalyst.展开更多
Two-dimensional （2D） materials with robust ferromagnetism have played a key role in realizing next- generation spin-electronic devices, but many challenges remain, especially the lack of intrinsic ferro- magnetic be...Two-dimensional （2D） materials with robust ferromagnetism have played a key role in realizing next- generation spin-electronic devices, but many challenges remain, especially the lack of intrinsic ferro- magnetic behavior in almost all 2D materials. Here, we highlight ultrathin Mn3O4 nanosheets as a new 2D ferromagnetic material with strong magnetocrystalline anisotropy. Magnetic measurements along the in-plane and out-of-plane directions confirm that the out-of-plane direction is the easy axis. The 2D-confined environment and Rashba-type spin-orbit coupling are thought to be responsible for the magnetocrystaUine anisotropy. The robust ferromagnetism in 2D MnaO4 nanosheets with magne- tocrystalline anisotropy not only paves a new way for realizing the intrinsic ferromagnetic behavior in 2D materials but also provides a novel candidate for building next-generation spin-electronic devices.展开更多
Na-ion batteries(SIBs)have attracted considerable attention as promising alternatives to commercial Li-ion batteries(LIBs)due to comparable redox potential,and natural abundance of Na.However,it remains challenging to...Na-ion batteries(SIBs)have attracted considerable attention as promising alternatives to commercial Li-ion batteries(LIBs)due to comparable redox potential,and natural abundance of Na.However,it remains challenging to explore suitable anodes for SIBs.Herein,a MoO2/N-doped carbon(MoO2/N-C)composite composed of MoO2 nanocrystals embedded within carbon matrix with a Mo–N–C chemical bond is prepared by a simple yet effective carbonization-induced topochemical transformation route.Na-ion half-cells using MoO2/N-C exhibit excellent cycling stability over 5000 cycles at 5 A g^-1 and superior rate capability.Physicochemical characterizations and first-principles density functional theory(DFT)simulations reveal that the formation of chemical bond at the interface between MoO2 and N-doped carbon plays an important role in the excellent charge storage properties of MoO2/N-C.More importantly,the interfacial coupling can efficiently promote interface charge transfer.Benefiting from this,Na-ion capacitors(SICs)constructed with the MoO2/N-C anode and activated carbon cathode can deliver an impressive energy density of 15 W h kg^-1 at a power density of 1760 W kg^-1,together with a capacitance retention of 92.4%over 1000 cycles at 10 A g^-1.The proposed strategy in this paper based on interfacial chemical bond may hold promises for the design of high-performance electrodes for energy storage devices.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.52322212,52025025,5225040212474001)the National Key R&D Program of China(Grant Nos.2022YFA1403203 and 2023YFA1406300)。
文摘Topochemical fluorination introduces significant structural distortions and emerging properties in perovskite oxides via substituting oxygen with fluorine.However,the rapid fluorination process and the similarity between F and O render the O/F site occupation and local lattice evolution during fluorination unclear.Here we investigated the atomic-scale O/F exchange in La2CoO4and quantified the lattice distortion of three ordered structures:La_(2)CoO_(3.5)F,La_(2)CoO_(3)F_(2),and La_(2)CoO_(2.5)F_(3)by utilizing aberration-corrected electron microscopy.Atomic-resolved elemental mapping provides direct evidence for the O/F occupancy in interstitial and apical sites.We revealed that apical F ions induce significant octahedral tilting from 178°to 165°,linearly proportional to the occupancy rate;and cause the obvious change in the fine structure O K edge,meanwhile apical O is exchanged into interstitial sites.The strong octahedral tilt leads to the in-plane elongation of the[CoO_(4)F_(2)]octahedra.These findings elucidate the atomic-scale mechanisms of the entire fluorination process and highlight the significant role of F in tuning the octahedral tilt of functional oxides.
文摘The underlying spin-related mechanism remains unclear,and the rational manipulation of spin states is challenging due to various spin configurations under different coordination conditions.Therefore,it is urgent to study spin-dependent oxygen evolution reaction(OER)performance through a controllable method.Herein,we adopt a topochemical reaction method to synthesize a series of selenides with eg occupancies ranging from 1.67 to 1.37.The process begins with monoclinic-CoSeO_(3),featuring a distinct laminar structure and Co-O6 coordination.The topochemical reaction induces significant changes in the crystal field's intensity,leading to spin state transitions.These transitions are driven by topological changes from a Co-O-Se-O-Co to a Co-Se-Co configuration,strengthening the crystalline field and reducing eg orbital occupancy.This reconfiguration of spin states shifts the rate-determining step from desorption to adsorption for both OER and the hydrogen evolution reaction(HER),reducing the potential-determined step barrier and enhancing overall catalytic efficiency.As a result,the synthesized cobalt selenide exhibits significantly enhanced adsorption capabilities.The material demonstrates impressive overpotentials of 35 mV for HER,250 mV for OER,and 270 mV for overall water splitting,indicating superior catalytic activity and efficiency.Additionally,a negative relation between eg filling and OER catalytic performance confirms the spin-dependent nature of OER.Our findings provide crucial insights into the role of spin state transitions in catalytic performance.
基金financial support from the Ministry of Science and Technology of the People's Republic of China(MOST,Nos.2017YFA0204501,2013CB834502)National Natural Science Foundation of China(NSFC,Nos.21773135,21473098 and 21421064)。
文摘Based on block copolymer assisted topochemical polymerization,a new strategy for facilely producing robust nanoporous membranes with controlled incorporation of functional groups onto nanopores is developed.As exemplified by preparing nanoporous polypyrrole decorated with amino acids,this strategy exhibits a high degree of freedom for tailoring the surface functionality in the created pores.
基金supported by the National Natural Science Foundation of China(NSFC, No. 21644005)National Program for Thousand Young Talents of ChinaState Key Project of Research and Development (No. 2016YFC1100300)
文摘The diphenyldiacetylene （DPDA） and the corresponding polymers has become one of hot research topics in the field of functional materials, due to its highly π-conjugated system and outstanding electrochemical properties. Compared with routine polydiacetylenes, polydiphenyldiacetylene （PDPDA） has wider π-extension within the whole polymer structure and a larger internlolecular stacking tendency. Since the preorganization of monomers is essential for the topochemical polymerization, we here introduce several self-assembled methods and external-templated methods for the proper alignment of DPDA. From the perspective of morphology, the monomer structures and external templates are two of the important factors towards polymerization. Based on its structure, PDPDA can become a promising intelligent material for various optoelectical applications, and specifically we summarize the application of PDPDA as an effective phtocatalyst in organic pollutants degradation
基金supported partially by project of the National Natural Science Foundation of China(Nos.52102203 and 51972110)Beijing Science and Technology Project(No.Z211100004621010)+4 种基金Beijing Natural Science Foundation(No.2222076)State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources(No.LAPS202114)Huaneng Group Headquarters Science and Technology Project(No.HNKJ20-H88)2022 Strategic Research Key Project of Science and Technology Commission of the Ministry of Education,the Fundamental Research Funds for the Central Universities(No.2024MS082)the NCEPU “Double First- Class” Program.
文摘Topochemical transformation has emerged as a promising method for fabricating two-dimensional (2D) materials with precise control over their composition and morphology. However, the large-scale synthesis of ultrathin 2D materials with controllable thickness remains a tremendous challenge. Herein, we adopt an efficient topochemical synthesis strategy, employing a confined reaction space to fabricate ultrathin 2D Sn_(4)P_(3) nanosheets in large-scale. By carefully adjusting the rolling number during the processing of Sn/Al foils, we have successfully fabricated Sn_(4)P_(3) nanosheets with varied layer thicknesses, achieving a remarkable minimum thickness of two layers (~ 2.2 nm). Remarkably, the bilayer Sn_(4)P_(3) nanosheets display an exceptional initial capacity of 1088 mAh·g^(−1), nearing the theoretical value of 1230 mAh·g^(−1). Furthermore, we reveal their high-rate property as well as outstanding cyclic stability, maintaining capacity without fading more than 3000 cycles. By precisely controlling the layer thickness and ensuring nanoscale uniformity, we enhance the lithium cycling performance of Sn_(4)P_(3), marking a significant advancement in developing high-performance energy storage systems.
文摘Silicon is the most promising anode material for the next generation high- performance lithium ion batteries. However, its commercial application is hindered by its poor performance due to the huge volume change during cycling. Although two-dimensional silicon-based materials show significantly improved performance, flexible synthesis of such materials is still a challenge. In this work, silicon-based nanosheets with a multilayer structure are synthesized for the first time by a topochemical reaction. The morphology and oxidation state of these nanosheets can be controlled by appropriate choice of reaction media and oxidants. Benefiting from the hierarchical structure and ultrathin size, when the silicon-based nanosheets are employed as anodes they exhibit a charge （delithiation） capacity of 800 mAh/g after 50 cycles with a maximum coulombic efficiency of 99.4% and good rate performance （647 mAh/g at 1 A/g）. This work demonstrates a novel method for preparing nanosheets not only for lithium ion batteries but also having various potential applications in other fields, such as catalysts, electronics and photonics.
基金supported by the Natural Science Foundation of China(22235001,22175020,22131005,22011540002,21631003)the Xiaomi Young Scholar Program+1 种基金the Fundamental Research Funds for the Central UniversitiesUniversity of Science and Technology Beijing
文摘Topochemical polymerization of molecular crystals into porous materials is of significance due to their promising applications in the field of adsorption and catalysis,yet rarely reported due to the synthesis difficulty.Herein,a hydrogen-bonded organic framework(HOF-45)has been fabricated by the crystallization of a cage-like building block containing three alkynyl groups.It exhibits almost mesoporous structure demonstrated by single crystal X-ray diffraction study.Light-driven topochemical polymerization of HOF-45 with ethanedithiol covalently links alkynyl groups in HOF-45,generating a hydrogen-bond and covalentbond cross-linked material(HOF-45C).In contrast to HOF-45,cross-linked HOF-45C retains the crystalline nature and displays improved solution resistence according to the powder X-ray diffraction data.In particular,HOF-45C is able to support the growth of ultrafine palladium nanoparticles with the average size of ca.1.9 nm for rapidly promoting the degradation of nitrophenol,methyl orange,and congo red with the help of NaBH_(4)as well as Suzuki-Miyaura coupling reaction.This work inputs a new idea on the HOFs application in preparing covalent-linked porous organic materials.
基金financially supported by the National Natural Science Foundation of China(NSFC,Nos.21875287,22090041)the Guangdong Basic and Applied Basic Research Foundation(No.2022B1515120014)。
文摘The intricate correlation between multiple degrees of freedom and physical properties is a fascinating area in solid state chemistry and condensed matter physics.Here,we report a quantum-magnetic system BaNi_(2)V_(2)O_(8)(BNVO),in which the spin correlation was modulated by unusual oxidation state,leading to different magnetic behavior.The BNVO was modified with topochemical reduction(TR)to yield TR-BNVO with partially reduced valance state of Ni^(+)in the two-dimensional NiO_(6)-honeycomb lattice.Accordingly,the antiferromagnetic order is suppressed by the introduction of locally interposed Ni^(+)and oxygen vacancies,resulting in a ferromagnetic ground state with the transition temperature up to 710 K.A positive magnetoresistance(7.5%)was observed in the TR-BNVO at 40 K under 7 T.These findings show that topological reduction is a powerful approach to engineer low-dimensional materials and accelerate the discovery of new quantum magnetism.
基金supported by Act 211 of the Government of the Russian Federation No.02.A03.21.0006the Ministry of Education and Science of Russia under government task No.4.1270.2014/K
文摘Topochemical ion-exchange reactions between solid micro- and nanostructured metal chalcogenides and aqueous salt solutions are generally used for formation of composite structures based on initial metal chalcogenides and products of their ion-exchange transformation. However, ion exchange has promises as a route to obtaining both composites and solid solutions based on the initial and the end chalcogenide phases. With the help of the ion-exchange technique, single-phase films of Phi xSnxSe substitutional solid solutions with a tin content up to -2 at.%, which are promising for mid- and long-wavelength infrared radiation （IR） optoelectronics, have been obtained at the interface between PbSe poly- crystalline thin films and SnCl2 aqueous solutions containing sodium citrate. It has been shown that the pH value and temperature of the reaction system play an important role in the ion-exchange process. Incubation of lead selenide （PbSe） films in a tin（II） salt aqueous solution also leads to their modification with oxygen-containing tin compounds to a depth of-3 nm. Differences in the film structure, such as changes in the coherent scattering region sizes and orientation of crystallites along the [220] direction, which arise during the contact with citrate-containing SnCl2 solutions, have also been revealed. For the first time, an idea of the existence of a relatively wide reaction zone of an intragranular topochemical ion-exchange reaction in an aqueous solution, within which substitutional solid solutions can form in micro- and nanostructured systems, has been set forth.
基金Project supported by the National Natural Science Foundation of China(Grant No.11404004)
文摘A novel and simple strategy of morphology-controlled Sr Ti O3（ST） micro-scale particle synthesis by the flux method is reported. Systematic experiments are designed to realize the tunable morphologies of the particles when the flux salt,sintering process, and the precursors are changed. The ST plates can be synthesized by plate-like Bi4Ti3O12（BIT） precursors in Na Cl flux. However, the as-synthesized Bi4Ti3O12 grains transform into reticular particles and finally into rods at higher temperature in Na Cl and KCl compounds. Besides, cubic ST particles are also prepared using different precursors as a comparative experiment. This study provides a strategy for further investigations in designing the morphology-controlled particles and efficient anisotropic materials of perovskite structure such as ferroelectric and photocatalyst.
基金This work was financially supported by the National Basic Research Program of China （Grant No. 2015CB932302）, the Youth Innovation Promotion Association CAS, the National Natural Science Foundation of China （Grant Nos. 21501164, U1632154, and J1030412）, National Young Top- Notch Talent Support Program, the Chinese Academy of Sciences （Grant No. XDB01020300）, the Fok Ying-Tong Education Foundation, China （Grant No. 141042）, the Anhui Provincial Natural Science Foundation （Grant No. 1608085QA08）, and tile Fundamental Research Funds for the Central Universities （Grant Nos. WK2060190027, WK2310000055, and WK2340000065）. We would like to thank the staff at beamlines BL14W1 （Shanghai Synchrotron Radiation Facility） for providing beam time and for their helpful discussions.
文摘Two-dimensional （2D） materials with robust ferromagnetism have played a key role in realizing next- generation spin-electronic devices, but many challenges remain, especially the lack of intrinsic ferro- magnetic behavior in almost all 2D materials. Here, we highlight ultrathin Mn3O4 nanosheets as a new 2D ferromagnetic material with strong magnetocrystalline anisotropy. Magnetic measurements along the in-plane and out-of-plane directions confirm that the out-of-plane direction is the easy axis. The 2D-confined environment and Rashba-type spin-orbit coupling are thought to be responsible for the magnetocrystaUine anisotropy. The robust ferromagnetism in 2D MnaO4 nanosheets with magne- tocrystalline anisotropy not only paves a new way for realizing the intrinsic ferromagnetic behavior in 2D materials but also provides a novel candidate for building next-generation spin-electronic devices.
基金supported by the National Natural Science Foundation of China(51804089)the Guangxi Key Laboratory of Electrochemical and Magneto-chemical Functional Materials(EMFM20181114)the support of the research starting foundation of CAEP(PY20200038)。
文摘Na-ion batteries(SIBs)have attracted considerable attention as promising alternatives to commercial Li-ion batteries(LIBs)due to comparable redox potential,and natural abundance of Na.However,it remains challenging to explore suitable anodes for SIBs.Herein,a MoO2/N-doped carbon(MoO2/N-C)composite composed of MoO2 nanocrystals embedded within carbon matrix with a Mo–N–C chemical bond is prepared by a simple yet effective carbonization-induced topochemical transformation route.Na-ion half-cells using MoO2/N-C exhibit excellent cycling stability over 5000 cycles at 5 A g^-1 and superior rate capability.Physicochemical characterizations and first-principles density functional theory(DFT)simulations reveal that the formation of chemical bond at the interface between MoO2 and N-doped carbon plays an important role in the excellent charge storage properties of MoO2/N-C.More importantly,the interfacial coupling can efficiently promote interface charge transfer.Benefiting from this,Na-ion capacitors(SICs)constructed with the MoO2/N-C anode and activated carbon cathode can deliver an impressive energy density of 15 W h kg^-1 at a power density of 1760 W kg^-1,together with a capacitance retention of 92.4%over 1000 cycles at 10 A g^-1.The proposed strategy in this paper based on interfacial chemical bond may hold promises for the design of high-performance electrodes for energy storage devices.
