Mg secondary batteries are promising scalable secondary batteries for next-generation energy storage.However,Mg-storage cathode materials are greatly demanded to construct high-performance Mg batteries.Electrochemical...Mg secondary batteries are promising scalable secondary batteries for next-generation energy storage.However,Mg-storage cathode materials are greatly demanded to construct high-performance Mg batteries.Electrochemical conversion reaction provides plenty of cathode options,and strategy for cathode selection and performance optimization is of special significance.In this work,Ni0.85Se with nanostructures of dispersive hexagonal nanosheets(D-Ni0.85Se)and flower-like assembled nanosheets(F-Ni0.85Se)is synthesized and investigated as Mg-storage cathodes.Compared with F-Ni0.85Se,D-Ni0.85Se delivers a higher specific capacity of 168 mAh g^-1 at 50 mA g^-1 as well as better rate performance,owing to its faster Mg^2+-diffusion and lower resistance.D-Ni0.85Se also exhibits a superior cycling stability over 500cycles.An investigation on mechanism indicates an evolution of Ni0.85Se towards NiSe with cycling,and the Mg-storage reaction occurs between NiSe and metallic Ni^0.The present work demonstrates that advanced conversion-type Mg battery cathode materials could be constructed by soft selenide anions,and the electrochemical properties could be manipulated by rational material morphology optimization.展开更多
Hexagonal boron nitride nanosheets （BNNSs） can work as a more efficient nucleating agent for two polyesters compared to graphene. Studies on the crystallization and dewetting processes of two polyesters, poly（butyl...Hexagonal boron nitride nanosheets （BNNSs） can work as a more efficient nucleating agent for two polyesters compared to graphene. Studies on the crystallization and dewetting processes of two polyesters, poly（butylene succinate） and poly（butylene adipate）, on the two substrate surfaces prove that the interaction between BNNSs and the polyesters is stronger than that between graphene and the polyesters. This strong interaction induces the pre-ordered conformation of molten PBA which has been identified by the in situ FTIR spectra. Thus BNNSs possess higher nucleation property than graphene. Finally, a new polymer-substrate interaction induced nucleation mechanism was proposed to explain the nucleation efficiency difference between graphene and BNNSs.展开更多
Two-dimensional nanomaterials were commonly used as lubrication additives.However,the high demand for the load-bearing capacity limited their industrial applications.This study proposed a new strategy to overcome this...Two-dimensional nanomaterials were commonly used as lubrication additives.However,the high demand for the load-bearing capacity limited their industrial applications.This study proposed a new strategy to overcome this limitation by depositing silver(Ag)nanoparticles on hexagonal boron nitride(hBN)nanosheets via dopamine through the reduction reaction of silver ions,and the Ag modified hBN nanosheets(hBN-Ag)were used as additives in aqueous ethylene glycol solution.The results showed that the superlubricity state with a minimum coefficient of friction(COF)of 0.004 at a maximum contact pressure of 1.20 GPa was achieved without the running-in period.The realization of superlubricity was attributed to the synergic effect of Ag nanoparticles and hBN nanosheets,where Ag nanoparticles were attached to the hBN nanosheets by dopamine,enhancing the load-bearing capacity of the hBN nanosheets.Simultaneously,the Ag modified hBN nanosheets were more easily adsorbed and deposited on the friction interface,generating the tribofilm containing hBN-Ag nanosheets through the tribochemical reaction,which reduced the direct contact of the friction pair and provided a low shear strength to generate extremely low friction.The Ag modified hBN nanosheets induced extremely low friction and wear,contributing to the development of lubricants with high loadbearing pressure and low wear rate.展开更多
Optical microscopy with optimal axial resolution is critical for precise visualization of two-dimensional flat-top structures.Here,we present sub-diffraction-limited ultrafast imaging of hexagonal boron nitride(hBN)na...Optical microscopy with optimal axial resolution is critical for precise visualization of two-dimensional flat-top structures.Here,we present sub-diffraction-limited ultrafast imaging of hexagonal boron nitride(hBN)nanosheets using a confocal focus-engineered coherent anti-Stokes Raman scattering(cFE-CARS)microscopic system.By incorporating a pinhole with a diameter of approximately 30μm,we effectively minimized the intensity of side lobes induced by circular partial pi-phase shift in the wavefront(diameter,d0)of the probe beam,as well as nonresonant background CARS intensities.Using axial-resolution-improved cFE-CARS(acFE-CARS),the achieved axial resolution is 350 nm,exhibiting a 4.3-folded increase in the signal-to-noise ratio compared to the previous case with 0.58 d0 phase mask.This improvement can be accomplished by using a phase mask of 0.24 d0.Additionally,we employed nonde-generate phase matching with three temporally separable incident beams,which facilitated cross-sectional visualization of highly-sample-specific and vibration-sensitive signals in a pump-probe fashion with subpicosecond time resolution.Our observations reveal time-dependent CARS dephasing in hBN nanosheets,induced by Raman-free induction decay(0.66 ps)in the 1373 cm^(−1) mode.展开更多
Boron(B)and nitrogen(N)co-doped 3D hierarchical micro/meso porous carbon(BNPC)were successfully fabricated from cellulose nanofiber(CNF)/boron nitride nanosheets(BNNS)/zinc-methylimidazolate framework-8(ZIF-8)nanocomp...Boron(B)and nitrogen(N)co-doped 3D hierarchical micro/meso porous carbon(BNPC)were successfully fabricated from cellulose nanofiber(CNF)/boron nitride nanosheets(BNNS)/zinc-methylimidazolate framework-8(ZIF-8)nanocomposites prepared by 2D BNNS,ZIF-8 nanoparticles,and wheat straw based CNFs.Herein,CNF/ZIF-8 acts as versatile skeleton and imparts partial N dopant into porous carbon structure,while the introduced BNNS can help strengthen the hierarchical porous superstructure and endow abundant B/N co-dopants within BNPC matrix.The obtained BNPC electrode possesses a high specific surface area of 505.4 m2/g,high B/N co-doping content,and desirable hydrophilicity.Supercapacitors assembled with BNPC-2(B/N co-doped porous carbon with a CNF/BNNS mass ratio of 1꞉2)electrodes exhibited exceptional electrochemical performance,demonstrating high capacitance stability even after 5000 charge-discharge cycles.The devices exhibited outstanding energy density and power density,as well as the highest specific capacitance of 433.4 F/g at 1.0 A/g,when compared with other similar reports.This study proposes a facile and sustainable strategy for efficiently fabrication of rich B/N co-doped hierarchical micro/meso porous carbon electrodes from agricultural waste biomass for advanced supercapacitor performance.展开更多
基金financially supported by Intergovernmental International Science and Technology Innovation Cooperation Project(2019YFE010186)the Hubei Provincial Natural Science Foundation(2019CFB452 and 2019CFB620)the Fundamental Research Funds for the Central Universities。
文摘Mg secondary batteries are promising scalable secondary batteries for next-generation energy storage.However,Mg-storage cathode materials are greatly demanded to construct high-performance Mg batteries.Electrochemical conversion reaction provides plenty of cathode options,and strategy for cathode selection and performance optimization is of special significance.In this work,Ni0.85Se with nanostructures of dispersive hexagonal nanosheets(D-Ni0.85Se)and flower-like assembled nanosheets(F-Ni0.85Se)is synthesized and investigated as Mg-storage cathodes.Compared with F-Ni0.85Se,D-Ni0.85Se delivers a higher specific capacity of 168 mAh g^-1 at 50 mA g^-1 as well as better rate performance,owing to its faster Mg^2+-diffusion and lower resistance.D-Ni0.85Se also exhibits a superior cycling stability over 500cycles.An investigation on mechanism indicates an evolution of Ni0.85Se towards NiSe with cycling,and the Mg-storage reaction occurs between NiSe and metallic Ni^0.The present work demonstrates that advanced conversion-type Mg battery cathode materials could be constructed by soft selenide anions,and the electrochemical properties could be manipulated by rational material morphology optimization.
基金financially supported by the National Basic Research Program of China(No.2014CB932202)the National Natural Science Foundation of China(Nos.51473085 and 21374054)the Sino-German Center for Research Promotion
文摘Hexagonal boron nitride nanosheets （BNNSs） can work as a more efficient nucleating agent for two polyesters compared to graphene. Studies on the crystallization and dewetting processes of two polyesters, poly（butylene succinate） and poly（butylene adipate）, on the two substrate surfaces prove that the interaction between BNNSs and the polyesters is stronger than that between graphene and the polyesters. This strong interaction induces the pre-ordered conformation of molten PBA which has been identified by the in situ FTIR spectra. Thus BNNSs possess higher nucleation property than graphene. Finally, a new polymer-substrate interaction induced nucleation mechanism was proposed to explain the nucleation efficiency difference between graphene and BNNSs.
基金financially supported by the National Key R&D Program of China(No.2020YFA0711003)the National Natural Science Foundation of China(Nos.52175174 and U2268212).
文摘Two-dimensional nanomaterials were commonly used as lubrication additives.However,the high demand for the load-bearing capacity limited their industrial applications.This study proposed a new strategy to overcome this limitation by depositing silver(Ag)nanoparticles on hexagonal boron nitride(hBN)nanosheets via dopamine through the reduction reaction of silver ions,and the Ag modified hBN nanosheets(hBN-Ag)were used as additives in aqueous ethylene glycol solution.The results showed that the superlubricity state with a minimum coefficient of friction(COF)of 0.004 at a maximum contact pressure of 1.20 GPa was achieved without the running-in period.The realization of superlubricity was attributed to the synergic effect of Ag nanoparticles and hBN nanosheets,where Ag nanoparticles were attached to the hBN nanosheets by dopamine,enhancing the load-bearing capacity of the hBN nanosheets.Simultaneously,the Ag modified hBN nanosheets were more easily adsorbed and deposited on the friction interface,generating the tribofilm containing hBN-Ag nanosheets through the tribochemical reaction,which reduced the direct contact of the friction pair and provided a low shear strength to generate extremely low friction.The Ag modified hBN nanosheets induced extremely low friction and wear,contributing to the development of lubricants with high loadbearing pressure and low wear rate.
基金National Research Foundation of Korea(2023R1A2C100531711)H.K.also acknowledges support from the DGIST R&D programs(22-CoENT-01 and 22-BT-06)funded by the Ministry of Science and ICT.V.R.acknowledges support from Department of Science and Technology(DST)Indo-Korea joint research project(INT/Korea/P-44).
文摘Optical microscopy with optimal axial resolution is critical for precise visualization of two-dimensional flat-top structures.Here,we present sub-diffraction-limited ultrafast imaging of hexagonal boron nitride(hBN)nanosheets using a confocal focus-engineered coherent anti-Stokes Raman scattering(cFE-CARS)microscopic system.By incorporating a pinhole with a diameter of approximately 30μm,we effectively minimized the intensity of side lobes induced by circular partial pi-phase shift in the wavefront(diameter,d0)of the probe beam,as well as nonresonant background CARS intensities.Using axial-resolution-improved cFE-CARS(acFE-CARS),the achieved axial resolution is 350 nm,exhibiting a 4.3-folded increase in the signal-to-noise ratio compared to the previous case with 0.58 d0 phase mask.This improvement can be accomplished by using a phase mask of 0.24 d0.Additionally,we employed nonde-generate phase matching with three temporally separable incident beams,which facilitated cross-sectional visualization of highly-sample-specific and vibration-sensitive signals in a pump-probe fashion with subpicosecond time resolution.Our observations reveal time-dependent CARS dephasing in hBN nanosheets,induced by Raman-free induction decay(0.66 ps)in the 1373 cm^(−1) mode.
基金support from the Natural Science Foundation of China (No.32101470)Foundation of Tianjin Key Laboratory of Pulp&Paper of Tianjin University of Science&Technology (No.202003,No.202106)+3 种基金China Postdoctoral Science Foundation (No.2022M712379,No.2021M692401)National Key Research and Development Plan (No.2022YFC2900031)Foundation of Guangxi Key Laboratory of Clean Pulp&Papermaking and Pollution Control,College of Light Industry and Food Engineering,Guangxi University (No.2021KF37)the support from Zhejiang Jingxing Paper Co.Ltd.,and University of New Brunswick.
文摘Boron(B)and nitrogen(N)co-doped 3D hierarchical micro/meso porous carbon(BNPC)were successfully fabricated from cellulose nanofiber(CNF)/boron nitride nanosheets(BNNS)/zinc-methylimidazolate framework-8(ZIF-8)nanocomposites prepared by 2D BNNS,ZIF-8 nanoparticles,and wheat straw based CNFs.Herein,CNF/ZIF-8 acts as versatile skeleton and imparts partial N dopant into porous carbon structure,while the introduced BNNS can help strengthen the hierarchical porous superstructure and endow abundant B/N co-dopants within BNPC matrix.The obtained BNPC electrode possesses a high specific surface area of 505.4 m2/g,high B/N co-doping content,and desirable hydrophilicity.Supercapacitors assembled with BNPC-2(B/N co-doped porous carbon with a CNF/BNNS mass ratio of 1꞉2)electrodes exhibited exceptional electrochemical performance,demonstrating high capacitance stability even after 5000 charge-discharge cycles.The devices exhibited outstanding energy density and power density,as well as the highest specific capacitance of 433.4 F/g at 1.0 A/g,when compared with other similar reports.This study proposes a facile and sustainable strategy for efficiently fabrication of rich B/N co-doped hierarchical micro/meso porous carbon electrodes from agricultural waste biomass for advanced supercapacitor performance.
