Sodium-ion batteries(SIBs)represent a highly promising class of energy storage devices.Enhancing SIBs performance necessitates innovative anode material development to overcome persistent challenges associated with th...Sodium-ion batteries(SIBs)represent a highly promising class of energy storage devices.Enhancing SIBs performance necessitates innovative anode material development to overcome persistent challenges associated with the large ionic radius of Na+,namely significant electrode volumetric expansion and sluggish reaction kinetics.Herein,a macroporous bimetallic(Co,Fe)selenide containing abundant heterojunction interfaces encapsulated into a carbon framework(M-CoSe2/FeSe2@C)is prepared by combining an in-situ crystallization strategy with carbonization-selenization treatment.The structural characterization reveals that the resulting M-CoSe2/FeSe2@C possesses a well-defined porous architecture with internal CoSe2-FeSe2 nanoparticles encapsulated by an external carbon matrix.This configuration not only enhances electrical conductivity but also stabilizes the composite structure throughout sodiation/desodiation cycling.Evaluated as an anode in SIBs,the M-CoSe2/FeSe2@C electrode delivers outstanding cycling stability(retaining 455.0 mA h g−1 at 0.2 A g−1 after 100 cycles)and exceptional rate capability(285.6 mA h g−1 at 10 A g−1).These superior properties are primarily attributed to the high density of interphase boundaries generated by the dual-phase configuration.Combined experimental and theoretical investigations demonstrate that these boundaries,particularly regions of high electron density on the FeSe2 side,kinetically favor Na+adsorption,thereby accelerating sodium storage kinetics.Furthermore,multi-step electrochemical reaction mechanisms within the composite were elucidated through in-situ and ex-situ characterization analyses.展开更多
The development of sodium-ion batteries(SIBs)is limited by slow charge transfer kinetics and large material volume changes caused by the large radius of Na+.Leveraging the excellent physicochemical properties and u...The development of sodium-ion batteries(SIBs)is limited by slow charge transfer kinetics and large material volume changes caused by the large radius of Na+.Leveraging the excellent physicochemical properties and unique heterostructures of metal selenides,ultrafine hetero-CuFeSe2-CoSe2nanoparticles are in situ wrapped by polyvinylpyrrolidone-derived carbon(PDC)to successfully synthesize multicomponent composite electrode materials(CuFeSe2-CoSe2@PDC)for SIB anodes.The carboncoated trimetallic selenide heterostructure synergistically enhances electronic/ionic conductivity while maintaining exceptional structural stability,thereby significantly improving the reaction kinetics of active materials.In addition,the exceptionally high pseudocapacitive contribution(97%at 1.0 mV s-1)plays a pivotal role in achieving high reversible specific capacity,excellent cycling stability,and superior rate capability.Benefiting from the multicomponent synergistic effects,the electrode delivers an exceptional specific capacity of 457.88 mAh g-1after 1000 cycles at 2 A g-1,with an ultralow average capacity decay rate of merely 0.0021%per cycle.Density functional theory(DFT)calculations further elucidate that the CuFeSe2-CoSe2heterointerface induces electronic structure reconstruction,and the generated built-in electric field promotes interfacial electrochemical kinetics.Ex situ X-ray diffraction(XRD)further revealed the reversible phase transformation reaction mechanism and confirmed the remarkable structural stability of CuFeSe2-CoSe2@PDC.This offers a feasible strategy to design highperformance electrodes capable of rapid and stable Na+storage.展开更多
This study presents the hydrothermal synthesis of a novel lanthanum selenide decorated graphene oxide(LaSe@GO)nanocomposite utilized as electrocatalyst for the non-enzymatic electrochemical sensing of dopamine(DA)and ...This study presents the hydrothermal synthesis of a novel lanthanum selenide decorated graphene oxide(LaSe@GO)nanocomposite utilized as electrocatalyst for the non-enzymatic electrochemical sensing of dopamine(DA)and ascorbic acid(AA).The morphological features,chemical and structural composition of the nanocomposite were characterized using a suite of analytical techniques including scanning electron microscopy(SEM),energy dispersive X-ray electron microscopy(EDX)and X-ray diffraction(XRD)pattern.LaSe@GO modified electrode exhibits exceptional dual sensing performance,achieving low detection limits of 0.04 mmol/L for DA and 0.1 mmol/L for AA and excellent selectivity against common interferents(e.g.,glucose,uric acid and sodium chloride).The sensor demonstrates high sensitivity of 0.55 and 0.25 mA/(mmol/(L·cm2))and broader linear ranges of 0.1-1.3 and 0.2-1.9 mmol/L for the DA and AA,respectively.Boosted performance of the synthesized nanocomposite is associated with the synergistic impact of active sites and enlarged surface area provided by the LaSe na noparticles and GO sheets,respectively.This work may pave the new perspective for the development in electrochemical sensors in term of innovative rare earth metal-based carbon nanocomposites.展开更多
Heterogeneous catalysts have attracted wide attention due to their remarkable oxygen evolution reaction(OER)capabilities.Herein,a one-step strategy involving the coupling of NixSeywith CeO2is proposed to concurrent...Heterogeneous catalysts have attracted wide attention due to their remarkable oxygen evolution reaction(OER)capabilities.Herein,a one-step strategy involving the coupling of NixSeywith CeO2is proposed to concurrently construct heterogeneous interfaces,adjust phase structure,and regulate electronic configuration,thereby enhancing OER performance.Thanks to the role of CeO2coupling in reducing the activation-energy and accelerating the reaction kinetics,the heterogeneous NixSey/CeO2catalyst exhibits a low overpotential of 218 mV at 10 mA/cm2and long-term stability(>400 h)in 1.0 mol/L KOH for OER.Moreover,the post-OER characterization reveals that the NixSeymatrix is reconstructed into NiOOH,while the incorporated CeO2nanocrystals self-assemble into larger polycrystalline particles.Theoretical analysis further demonstrates that the optimized electronic states at NiOOH/CeO2interfaces can modulate intermediate chemisorption toward favorable OER kinetics.This study offers fresh perspectives on the synthesis and structure-activity relationship of CeO2-coupled electrocatalysts.展开更多
A simple and convenient procedure for stercoselective synthesis of (Z)-allyl selenides has been developed by a one-pot reaction of diselenides with Baylis-Hillman adducts in the presence of samarium metal-trimethyls...A simple and convenient procedure for stercoselective synthesis of (Z)-allyl selenides has been developed by a one-pot reaction of diselenides with Baylis-Hillman adducts in the presence of samarium metal-trimethylsilyl chloride under mild conditions. Presumably, the diselenides are cleaved by Sm/TMSCI system to form selemde anions, which then undergo SN2' substitution of Baylis-Hillman adducts to produce the (Z)-allyl selenides.展开更多
Reduction of diaryldiselenides by the system of Cp2TiCl2/Bu'MgBr/THF gave the nucleophilic arylselenium complex. They reacted with diaryl iodonium salts to afford unsymmetrical diaryl selenides in high yields.
Alkynyl selenides were prepared under very mild conditions by reacting terminal alkynes with respective diorganic diselenides in the presence of potassium t-butoxide. The advantages of this protocol include the use of...Alkynyl selenides were prepared under very mild conditions by reacting terminal alkynes with respective diorganic diselenides in the presence of potassium t-butoxide. The advantages of this protocol include the use of readily available substrates and reagent and good yield of the products.展开更多
Recently,metal selenides have obtained widespread attention as electrode materials for alkali(Li+/Na+/K+)batteries due to their promising theoretical capacity and mechanism.Nevertheless,metal selenides,simila...Recently,metal selenides have obtained widespread attention as electrode materials for alkali(Li+/Na+/K+)batteries due to their promising theoretical capacity and mechanism.Nevertheless,metal selenides,similar to metal oxides and sulfides,also suffer from severe volume explosion during repeated charge/discharge processes,which results in the structure collapse and the following pulverization of electrode materials.Hence,it leads to poor cycle stability and influencing their further application.In order to solve these issues,some special strategies,including elemental doping,coupling with carbon materials,synthesis of the bimetal selenides with heterostructure,etc.,have been gradually applied to design novel electrode materials with outstanding electrochemical performance.Herein,the recent research progress on metal selenides as anodes for alkali ion batteries is summarized,including the regulation of crystal structure,synthesis strategies,modification methods,and electrochemical mechanisms and kinetics.Besides,the challenges of metal selenides and the perspective for future electrode material design are proposed.It is hoped to pave a way for the development of metal selenide electrode materials for the potential applications for alkali metal ion(Li+/Na+/K+)batteries.展开更多
The shell structure design has been recognized as a highly efficient strategy to buffer the severe volume expansion and consecutive pulverization of conversion-type anodes.Nevertheless,construction of a functional she...The shell structure design has been recognized as a highly efficient strategy to buffer the severe volume expansion and consecutive pulverization of conversion-type anodes.Nevertheless,construction of a functional shell with a stabilized structure that meets the demands of both high electronic conductivity and feasible pathways for Na+ions has been a challenge so far.Herein,we design a two-in-one shell configuration for bimetal selenides to achieve fast sodium storage within broadened voltage windows.The hybridized shell,which benefits from the combination of titanium dioxide quantum dots and amorphous carbon,can not only effectively buffer the strain and maintain structural integrity but also allow facile and reversible transport of electrons and Na+uptake for electrode materials during sodiation/desodiation processes,resulting in increased reaction kinetics and diffusion of sodium ions,conferring many benefits to the functionality of conversion-type electrode materials.As a representative material,Ni-CoSe2 with such structural engineering shows a reversible capacity of 515 mAh g−1at 0.1 A g−1and a stable capacity of 416 mAh g−1even at 6.4 A g−1;more than 80%of the capacity at 0.1 A g−1could be preserved,so that this strategy holds great promise for designing fast-charging conversion-type anodes in the future.展开更多
Bimetallic selenide with core-shell structure(CoSe2/ZnSe/NC@ZnSe/NC)has been successfully prepared through facile carbonization and selenization processes of its core-shell metal-organic framework precursors,in whi...Bimetallic selenide with core-shell structure(CoSe2/ZnSe/NC@ZnSe/NC)has been successfully prepared through facile carbonization and selenization processes of its core-shell metal-organic framework precursors,in which the precursor is synthesized by epitaxial growth of zinc-based zeolite imidazolate framework(ZIF-8)on the surface of cobalt-based and zinc-based zeolite imidazolate framework(ZIF-67@ZIF-8).The coreshell structure has the advantage of alleviating the volume expansion during repeated insertion and extraction of sodium ions which can effectively avoid structural collapse.Additionally,bimetallic selenides and heterostructure are effective strategies to greatly improve the rate capability of the material.Therefore,the core-shell structural CoSe2/ZnSe/NC@ZnSe/NC material can maintain the original dodecahedron structure and delivers a specific capacity of 308.6 mAh·g-1at 1.0 A·g-1after 300 cycles with the desirable capacity retention of 90%.With the synergistic effects of heterostructure and core-shell structure,CoSe2/ZnSe/NC@ZnSe/NC exhibits better electrochemical performance than CoSe2/ZnSe/NC and CoSe2/NC.These prove that both core-shell structure and heterostructure have positive effects on improving the electrochemical properties of materials.展开更多
In the presence of catalytic amount of cesium hydroxide the hydrothiolation of alkynyl selenides occurred at room temperature in DMF under nitrogen atmosphere to give exclusive(Z)-1-organoseleno-2-arylthio-1-alkene ...In the presence of catalytic amount of cesium hydroxide the hydrothiolation of alkynyl selenides occurred at room temperature in DMF under nitrogen atmosphere to give exclusive(Z)-1-organoseleno-2-arylthio-1-alkene in excellent yields.It could provide a new and expedient way for the preparation of(Z)-1-arylseleno-2-arylthio-1-alkene.展开更多
In the presence of BiCl3/Al or BiCl3/Fe, in THF-H2O, allylic (benzylic) bromides or α-bromoketones react with diorganyl diselenides to give allylic (benzylic) selenides orα-organylselenocarbonyl compounds respective...In the presence of BiCl3/Al or BiCl3/Fe, in THF-H2O, allylic (benzylic) bromides or α-bromoketones react with diorganyl diselenides to give allylic (benzylic) selenides orα-organylselenocarbonyl compounds respectively in moderate to good yields.展开更多
A mild, one-pot procedure for the synthesis of vinyl ethers in good yields from 2-hydroxyalkyl phenyl selenides with primary or secondary organic halides has been developed.
Several polystyrene-supported selenides and selenoxide have been prepared firstly. These novel reagents were treated with LDA to produce selenium stabilized carbanions, which reacted with aldehydes and alkyl halides, ...Several polystyrene-supported selenides and selenoxide have been prepared firstly. These novel reagents were treated with LDA to produce selenium stabilized carbanions, which reacted with aldehydes and alkyl halides, followed by selenoxide syn-elimination and [2,3] sigmatropic rearrangement respectively to give Z-allylic alcohols stereoselectively.展开更多
Cost-effective and stable electrocatalysts with ultra-high current densities for electrochemical oxygen evolution reaction(OER)are critical to the energy crisis and environmental pollution.Herein,we report a superaero...Cost-effective and stable electrocatalysts with ultra-high current densities for electrochemical oxygen evolution reaction(OER)are critical to the energy crisis and environmental pollution.Herein,we report a superaerophobic three dimensional(3D)heterostructured nanowrinkles of bimetallic selenides consisting of crystalline NiSe2 and NiFe2Se4 grown on NiFe alloy(NiSe2/NiFe2Se4@NiFe)prepared by a thermal selenization procedure.In this unique 3D heterostructure,numerous nanowrinkles of NiSe2/NiFe2Se4 hybrid with a thickness of ~100 nm are grown on NiFe alloy in a uniform manner.Profiting by the large active surface area and high electronic conductivity,the superaerophobic NiSe2/NiFe2Se4@NiFe heterostructure exhibits excellent electrocatalytic activity and durability towards OER in alkaline media,outputting the low potentials of 1.53 and 1.54 V to achieve ultra-high current densities of 500 and 1000 mA cm^−2,respectively,which is among the most active Ni/Fe-based selenides,and even superior to the benchmark Ir/C catalyst.The in-situ derived FeOOH and NiOOH species from NiSe2/NiFe2Se4@NiFe are deemed to be efficient active sites for OER.展开更多
Lithium-sulfur batteries(LSBs)have attracted the attention of more and more researchers due to the advantages of high energy density,environmental friendliness,and low production cost.However,the low electronic conduc...Lithium-sulfur batteries(LSBs)have attracted the attention of more and more researchers due to the advantages of high energy density,environmental friendliness,and low production cost.However,the low electronic conductivity of active material and shuttling effect of lithium polysulfides(LiPSs)limit the commercial development of LSBs.To solve these problems,we design a core-shell composite with nitrogen-doped carbon(NC)and two types of selenides(FeSe2-NC@ZnSe-NC).The FeSe2-NC@ZnSe-NC has a strong adsorption capacity,and can effectively adsorb LiPSs.At the same time,it also effectively alleviates the shuttling effect of LiPSs,and improves the utilization of the active substance during the charge/discharge reaction processes.The mechanism involved in FeSe2-NC@ZnSe-NC is demonstrated by both experiments and density-functional theory(DFT)calculations.The electrochemical test results indicate that LSB with S/FeSe2-NC@ZnSe-NC delivers an initial discharge capacity of 1260 mAh·g-1at 0.2C.And after 500 cycles at 1C,the capacity decay rate per cycle is 0.031%,and the capacity retention rate is 85%.The FeSe2-NC@ZnSe-NC core-shell structure verifies a rational strategy to construct an electrode material for high-performance LSBs.展开更多
The insertion of elemental selenium into the Csp(2)-Zr bond of alkenylchloro-zirconocenes affords (E)-vinylseleno zirconocenes, which were trapped by alkyl halides giving (E)-vinylic selenides in moderate to good yields.
基金support from the National Natural Science Foundation of China(Grant 51573058)funding provided through the Postdoctoral Fellowship Program(Grade C)of the China Postdoctoral Science Foundation(GZC20240629).
摘要Sodium-ion batteries(SIBs)represent a highly promising class of energy storage devices.Enhancing SIBs performance necessitates innovative anode material development to overcome persistent challenges associated with the large ionic radius of Na+,namely significant electrode volumetric expansion and sluggish reaction kinetics.Herein,a macroporous bimetallic(Co,Fe)selenide containing abundant heterojunction interfaces encapsulated into a carbon framework(M-CoSe2/FeSe2@C)is prepared by combining an in-situ crystallization strategy with carbonization-selenization treatment.The structural characterization reveals that the resulting M-CoSe2/FeSe2@C possesses a well-defined porous architecture with internal CoSe2-FeSe2 nanoparticles encapsulated by an external carbon matrix.This configuration not only enhances electrical conductivity but also stabilizes the composite structure throughout sodiation/desodiation cycling.Evaluated as an anode in SIBs,the M-CoSe2/FeSe2@C electrode delivers outstanding cycling stability(retaining 455.0 mA h g−1 at 0.2 A g−1 after 100 cycles)and exceptional rate capability(285.6 mA h g−1 at 10 A g−1).These superior properties are primarily attributed to the high density of interphase boundaries generated by the dual-phase configuration.Combined experimental and theoretical investigations demonstrate that these boundaries,particularly regions of high electron density on the FeSe2 side,kinetically favor Na+adsorption,thereby accelerating sodium storage kinetics.Furthermore,multi-step electrochemical reaction mechanisms within the composite were elucidated through in-situ and ex-situ characterization analyses.
基金financially supported by the National Natural Science Foundation of China(Grant No.22305104)the Natural Science Foundation of Jiangsu Province(Grant No.BK20210893)。
摘要The development of sodium-ion batteries(SIBs)is limited by slow charge transfer kinetics and large material volume changes caused by the large radius of Na+.Leveraging the excellent physicochemical properties and unique heterostructures of metal selenides,ultrafine hetero-CuFeSe2-CoSe2nanoparticles are in situ wrapped by polyvinylpyrrolidone-derived carbon(PDC)to successfully synthesize multicomponent composite electrode materials(CuFeSe2-CoSe2@PDC)for SIB anodes.The carboncoated trimetallic selenide heterostructure synergistically enhances electronic/ionic conductivity while maintaining exceptional structural stability,thereby significantly improving the reaction kinetics of active materials.In addition,the exceptionally high pseudocapacitive contribution(97%at 1.0 mV s-1)plays a pivotal role in achieving high reversible specific capacity,excellent cycling stability,and superior rate capability.Benefiting from the multicomponent synergistic effects,the electrode delivers an exceptional specific capacity of 457.88 mAh g-1after 1000 cycles at 2 A g-1,with an ultralow average capacity decay rate of merely 0.0021%per cycle.Density functional theory(DFT)calculations further elucidate that the CuFeSe2-CoSe2heterointerface induces electronic structure reconstruction,and the generated built-in electric field promotes interfacial electrochemical kinetics.Ex situ X-ray diffraction(XRD)further revealed the reversible phase transformation reaction mechanism and confirmed the remarkable structural stability of CuFeSe2-CoSe2@PDC.This offers a feasible strategy to design highperformance electrodes capable of rapid and stable Na+storage.
基金Project supported by the Deanship of Scientific Research at King Faisal University,under the Ambient Researcher(Grant,KFU 252476)。
摘要This study presents the hydrothermal synthesis of a novel lanthanum selenide decorated graphene oxide(LaSe@GO)nanocomposite utilized as electrocatalyst for the non-enzymatic electrochemical sensing of dopamine(DA)and ascorbic acid(AA).The morphological features,chemical and structural composition of the nanocomposite were characterized using a suite of analytical techniques including scanning electron microscopy(SEM),energy dispersive X-ray electron microscopy(EDX)and X-ray diffraction(XRD)pattern.LaSe@GO modified electrode exhibits exceptional dual sensing performance,achieving low detection limits of 0.04 mmol/L for DA and 0.1 mmol/L for AA and excellent selectivity against common interferents(e.g.,glucose,uric acid and sodium chloride).The sensor demonstrates high sensitivity of 0.55 and 0.25 mA/(mmol/(L·cm2))and broader linear ranges of 0.1-1.3 and 0.2-1.9 mmol/L for the DA and AA,respectively.Boosted performance of the synthesized nanocomposite is associated with the synergistic impact of active sites and enlarged surface area provided by the LaSe na noparticles and GO sheets,respectively.This work may pave the new perspective for the development in electrochemical sensors in term of innovative rare earth metal-based carbon nanocomposites.
基金supported by the grants from the National Natural Science Foundation of China(No.22202098)the Natural Science Foundation of Henan Province(No.242300420199)。
摘要Heterogeneous catalysts have attracted wide attention due to their remarkable oxygen evolution reaction(OER)capabilities.Herein,a one-step strategy involving the coupling of NixSeywith CeO2is proposed to concurrently construct heterogeneous interfaces,adjust phase structure,and regulate electronic configuration,thereby enhancing OER performance.Thanks to the role of CeO2coupling in reducing the activation-energy and accelerating the reaction kinetics,the heterogeneous NixSey/CeO2catalyst exhibits a low overpotential of 218 mV at 10 mA/cm2and long-term stability(>400 h)in 1.0 mol/L KOH for OER.Moreover,the post-OER characterization reveals that the NixSeymatrix is reconstructed into NiOOH,while the incorporated CeO2nanocrystals self-assemble into larger polycrystalline particles.Theoretical analysis further demonstrates that the optimized electronic states at NiOOH/CeO2interfaces can modulate intermediate chemisorption toward favorable OER kinetics.This study offers fresh perspectives on the synthesis and structure-activity relationship of CeO2-coupled electrocatalysts.
基金Project (No. 2004C21032) supported by the Key Technologies R &D Program of Zhejiang Province, China
摘要A simple and convenient procedure for stercoselective synthesis of (Z)-allyl selenides has been developed by a one-pot reaction of diselenides with Baylis-Hillman adducts in the presence of samarium metal-trimethylsilyl chloride under mild conditions. Presumably, the diselenides are cleaved by Sm/TMSCI system to form selemde anions, which then undergo SN2' substitution of Baylis-Hillman adducts to produce the (Z)-allyl selenides.
摘要Reduction of diaryldiselenides by the system of Cp2TiCl2/Bu'MgBr/THF gave the nucleophilic arylselenium complex. They reacted with diaryl iodonium salts to afford unsymmetrical diaryl selenides in high yields.
基金the K.N.Toosi University of Technology Research Council for financial assistance
摘要Alkynyl selenides were prepared under very mild conditions by reacting terminal alkynes with respective diorganic diselenides in the presence of potassium t-butoxide. The advantages of this protocol include the use of readily available substrates and reagent and good yield of the products.
基金supported by the National Natural Science Foundation of China(Nos.51563002 and 52101243)the"100-level"Innovative Talents Project of Guizhou Province,China(No.[2016]5653)+1 种基金the Natural Science Foundation of Guangdong Province(No.2020A1515010886)the Science and Technology Planning Project of Guangzhou(No.202102010373)。
摘要Recently,metal selenides have obtained widespread attention as electrode materials for alkali(Li+/Na+/K+)batteries due to their promising theoretical capacity and mechanism.Nevertheless,metal selenides,similar to metal oxides and sulfides,also suffer from severe volume explosion during repeated charge/discharge processes,which results in the structure collapse and the following pulverization of electrode materials.Hence,it leads to poor cycle stability and influencing their further application.In order to solve these issues,some special strategies,including elemental doping,coupling with carbon materials,synthesis of the bimetal selenides with heterostructure,etc.,have been gradually applied to design novel electrode materials with outstanding electrochemical performance.Herein,the recent research progress on metal selenides as anodes for alkali ion batteries is summarized,including the regulation of crystal structure,synthesis strategies,modification methods,and electrochemical mechanisms and kinetics.Besides,the challenges of metal selenides and the perspective for future electrode material design are proposed.It is hoped to pave a way for the development of metal selenide electrode materials for the potential applications for alkali metal ion(Li+/Na+/K+)batteries.
基金Fundamental Research Funds for the Central Universities,Grant/Award Numbers:531118010111,531118010633National Natural Science Foundation of China,Grant/Award Numbers:22109041,52103313。
摘要The shell structure design has been recognized as a highly efficient strategy to buffer the severe volume expansion and consecutive pulverization of conversion-type anodes.Nevertheless,construction of a functional shell with a stabilized structure that meets the demands of both high electronic conductivity and feasible pathways for Na+ions has been a challenge so far.Herein,we design a two-in-one shell configuration for bimetal selenides to achieve fast sodium storage within broadened voltage windows.The hybridized shell,which benefits from the combination of titanium dioxide quantum dots and amorphous carbon,can not only effectively buffer the strain and maintain structural integrity but also allow facile and reversible transport of electrons and Na+uptake for electrode materials during sodiation/desodiation processes,resulting in increased reaction kinetics and diffusion of sodium ions,conferring many benefits to the functionality of conversion-type electrode materials.As a representative material,Ni-CoSe2 with such structural engineering shows a reversible capacity of 515 mAh g−1at 0.1 A g−1and a stable capacity of 416 mAh g−1even at 6.4 A g−1;more than 80%of the capacity at 0.1 A g−1could be preserved,so that this strategy holds great promise for designing fast-charging conversion-type anodes in the future.
基金financially supported by the National Natural Science Foundation of China(Nos.52101243 and 51563002)the Natural Science Foundation of Guangdong Province(Nos.2020A1515010886 and 2021A1515010078)+1 种基金the Scientific and Technological Plan of Guangdong Province,China(No.2019B090905007)the Science and Technology Planning Project of Guangzhou(No.202102010373)。
摘要Bimetallic selenide with core-shell structure(CoSe2/ZnSe/NC@ZnSe/NC)has been successfully prepared through facile carbonization and selenization processes of its core-shell metal-organic framework precursors,in which the precursor is synthesized by epitaxial growth of zinc-based zeolite imidazolate framework(ZIF-8)on the surface of cobalt-based and zinc-based zeolite imidazolate framework(ZIF-67@ZIF-8).The coreshell structure has the advantage of alleviating the volume expansion during repeated insertion and extraction of sodium ions which can effectively avoid structural collapse.Additionally,bimetallic selenides and heterostructure are effective strategies to greatly improve the rate capability of the material.Therefore,the core-shell structural CoSe2/ZnSe/NC@ZnSe/NC material can maintain the original dodecahedron structure and delivers a specific capacity of 308.6 mAh·g-1at 1.0 A·g-1after 300 cycles with the desirable capacity retention of 90%.With the synergistic effects of heterostructure and core-shell structure,CoSe2/ZnSe/NC@ZnSe/NC exhibits better electrochemical performance than CoSe2/ZnSe/NC and CoSe2/NC.These prove that both core-shell structure and heterostructure have positive effects on improving the electrochemical properties of materials.
基金Natural Science Foundation of Hunan(No.2009NK3162)National Natural Science Foundation of China(No.21003040,20372020) for financial support
摘要In the presence of catalytic amount of cesium hydroxide the hydrothiolation of alkynyl selenides occurred at room temperature in DMF under nitrogen atmosphere to give exclusive(Z)-1-organoseleno-2-arylthio-1-alkene in excellent yields.It could provide a new and expedient way for the preparation of(Z)-1-arylseleno-2-arylthio-1-alkene.
基金the Natural Science Foundation of the Education Commission of Jiangsu Province
摘要In the presence of BiCl3/Al or BiCl3/Fe, in THF-H2O, allylic (benzylic) bromides or α-bromoketones react with diorganyl diselenides to give allylic (benzylic) selenides orα-organylselenocarbonyl compounds respectively in moderate to good yields.
基金the Natural Science Foundation of Jiangxi Province(No.0420017)for financial support
摘要A mild, one-pot procedure for the synthesis of vinyl ethers in good yields from 2-hydroxyalkyl phenyl selenides with primary or secondary organic halides has been developed.
摘要Several polystyrene-supported selenides and selenoxide have been prepared firstly. These novel reagents were treated with LDA to produce selenium stabilized carbanions, which reacted with aldehydes and alkyl halides, followed by selenoxide syn-elimination and [2,3] sigmatropic rearrangement respectively to give Z-allylic alcohols stereoselectively.
基金financially supported by the National Natural Science Foundation of China(21922811,51702284,and 21878270)Zhejiang Provincial Natural Science Foundation of China(LR19B060002)the Startup Foundation for Hundred-Talent Program of Zhejiang University.
摘要Cost-effective and stable electrocatalysts with ultra-high current densities for electrochemical oxygen evolution reaction(OER)are critical to the energy crisis and environmental pollution.Herein,we report a superaerophobic three dimensional(3D)heterostructured nanowrinkles of bimetallic selenides consisting of crystalline NiSe2 and NiFe2Se4 grown on NiFe alloy(NiSe2/NiFe2Se4@NiFe)prepared by a thermal selenization procedure.In this unique 3D heterostructure,numerous nanowrinkles of NiSe2/NiFe2Se4 hybrid with a thickness of ~100 nm are grown on NiFe alloy in a uniform manner.Profiting by the large active surface area and high electronic conductivity,the superaerophobic NiSe2/NiFe2Se4@NiFe heterostructure exhibits excellent electrocatalytic activity and durability towards OER in alkaline media,outputting the low potentials of 1.53 and 1.54 V to achieve ultra-high current densities of 500 and 1000 mA cm^−2,respectively,which is among the most active Ni/Fe-based selenides,and even superior to the benchmark Ir/C catalyst.The in-situ derived FeOOH and NiOOH species from NiSe2/NiFe2Se4@NiFe are deemed to be efficient active sites for OER.
基金financially supported by the National Natural Science Foundation of China(No.52130101)the Project of Science and Technology Development Plan of Jilin Province in China(Nos.20210402058GH and 20220201114GX)。
摘要Lithium-sulfur batteries(LSBs)have attracted the attention of more and more researchers due to the advantages of high energy density,environmental friendliness,and low production cost.However,the low electronic conductivity of active material and shuttling effect of lithium polysulfides(LiPSs)limit the commercial development of LSBs.To solve these problems,we design a core-shell composite with nitrogen-doped carbon(NC)and two types of selenides(FeSe2-NC@ZnSe-NC).The FeSe2-NC@ZnSe-NC has a strong adsorption capacity,and can effectively adsorb LiPSs.At the same time,it also effectively alleviates the shuttling effect of LiPSs,and improves the utilization of the active substance during the charge/discharge reaction processes.The mechanism involved in FeSe2-NC@ZnSe-NC is demonstrated by both experiments and density-functional theory(DFT)calculations.The electrochemical test results indicate that LSB with S/FeSe2-NC@ZnSe-NC delivers an initial discharge capacity of 1260 mAh·g-1at 0.2C.And after 500 cycles at 1C,the capacity decay rate per cycle is 0.031%,and the capacity retention rate is 85%.The FeSe2-NC@ZnSe-NC core-shell structure verifies a rational strategy to construct an electrode material for high-performance LSBs.
摘要The insertion of elemental selenium into the Csp(2)-Zr bond of alkenylchloro-zirconocenes affords (E)-vinylseleno zirconocenes, which were trapped by alkyl halides giving (E)-vinylic selenides in moderate to good yields.