Fluorination is a critical surface modification technique for enhancing the electrical performance of composite insulators.This study employs molecular simulations to examine the microstructure and space charge behavi...Fluorination is a critical surface modification technique for enhancing the electrical performance of composite insulators.This study employs molecular simulations to examine the microstructure and space charge behavior of fluorinated and non-fluorinated silicone rubber under an electric field,with experimental validation.The results show that fluorinated silicone rubber exhibits lower total energy,higher polarization,and stronger dipole moments compared to its non-fluorinated counterpart,shifting the material from an insulating to a conductive state.Under lower electric field strengths,the carbon-silicon bonds in fluorinated silicone rubber are longer,but it maintains geometric stability under higher fields.The energy gap changes across different fluorination modes and varies with electric field strength,indicating that fluorination affects conductivity differently at various field intensities.Both fluorination methods improve conductivity in the 0–3.8 V/nm range,with substitutional fluorination showing superior performance between 3.8 and 8.9 V/nm.Above 9.1 V/nm,fluorination maximizes conductivity.The fluorinated samples exhibit a greater redshift at higher electric fields,resulting in enhanced conductivity and improved surface charge distribution.These findings offer insights into the microscopic effects of fluorination on silicone rubber’s electrical properties,while experiments confirm that fluorination increases hydrophobicity and boosts DC flashover voltage,further enhancing the material’s performance.展开更多
Ag_(2)CO_(3)-promoted dehydroxymethylative fluorination of aliphatic alcohols has been achieved with Selectfluor as both oxidant and fluorine source.The reaction involvesβ-fragmentation of primary alkoxy radicals,fol...Ag_(2)CO_(3)-promoted dehydroxymethylative fluorination of aliphatic alcohols has been achieved with Selectfluor as both oxidant and fluorine source.The reaction involvesβ-fragmentation of primary alkoxy radicals,followed by the fluorination of the resulting C-centered radical intermediates.The transformation proceeds under mild reaction conditions and exhibits a broad substrate scope,thus opening up a new entrance to the synthesis of fluorinated constructs includingα-fluoroimides and 1-fluoroalkyl benzoates as well as secondary and tertiary alkyl fluorides like versatile 2-fluoro-2-alkyl 1,3-propandiol derivatives.The divergent functionalization of the obtainedα-fluoroimides enables an efficient access to amine derivatives through C-F bond activation under the action of BF_(3)·OEt_(2).展开更多
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
Here we present a highly efficient protocol utilizing nickel-hydride hydrogen atom transfer catalysis for the regio-and enantioselective hydrofluorination of internal alkenes.This method efficiently assembles a wide a...Here we present a highly efficient protocol utilizing nickel-hydride hydrogen atom transfer catalysis for the regio-and enantioselective hydrofluorination of internal alkenes.This method efficiently assembles a wide array of enantioenrichedβ-fluoro amides with excellent regio-and enantioselectivity from internal unactivated alkenes.Mechanistic investigations suggest that this transformation proceeds via a NiHhydrogen atom transfer to alkene,followed by a stereoselective fluorine atom transfer process.The weak coordination effect of the tethered amide group is identified as a crucial factor governing the observed regio-and enantioselectivity.展开更多
High-voltage solid-state lithium-ion batteries(SSLIBs)have attracted considerable research attention in recent years due to their high-energy-density and superior safety characteristics.However,the integration of high...High-voltage solid-state lithium-ion batteries(SSLIBs)have attracted considerable research attention in recent years due to their high-energy-density and superior safety characteristics.However,the integration of high-voltage cathodes with solid electrolytes(SEs)presents multiple challenges,including the formation of high-impedance layers from spontaneous chemical reactions,electrochemical instability,insufficient interfacial contact,and lattice expansion.These issues significantly impair battery performance and potentially lead to battery failure,thus impeding the commercialization of high-voltage SSLIBs.The incorporation of fluorides,known for their robust bond strength and high free energy of formation,has emerged as an effective strategy to address these challenges.Fluorinated electrolytes and electrode/electrolyte interfaces have been demonstrated to significantly influence the reaction reversibility/kinetics,safety,and stability of rechargeable batteries,particularly under high voltage.This review summarizes recent advancements in fluorination treatment for high-voltage SEs,focusing on solid polymer electrolytes(SPEs),inorganic solid electrolytes(ISEs),and composite solid electrolytes(CSEs),along with the performance enhancements these strategies afford.This review aims to provide a comprehensive understanding of the structure-property relationships,the characteristics of fluorinated interfaces,and the application of fluorinated SEs in high-voltage SSLIBs.Further,the impacts of residual moisture and the challenges of fluorinated SEs are discussed.Finally,the review explores potential future directions for the development of fluorinated SSLIBs.展开更多
To advance the application of layered oxide cathodes in fast-charging sodium-ion batteries,it is crucial to not only suppress irreversible phase transitions but also improve the rate capability of cathode materials an...To advance the application of layered oxide cathodes in fast-charging sodium-ion batteries,it is crucial to not only suppress irreversible phase transitions but also improve the rate capability of cathode materials and optimize Na^(+)diffusion kinetics to ensure high capacity output at various charge-discharge rates.In this research,the targeted F-substitution with a heavy ratio in oxygen anion layer optimizes the Na^(+)diffusion path and electronic conductivity of the material,thereby decreasing the Na^(+)diffusion barrier and imparting high-rate performance.At a 20 C rate,the cathode achieves a capacity of over 80 mAh g^(-1)with stable cycling performance.Additionally,the dual rivet effect between the transition metal layer and oxygen layer prevents significant phase transitions during charge/discharge within the 2-4.2 V range for the modified cathode.As a result,the F-substituted oxygen anion layer improved Na^(+)diffusion,electronic conductivity,and crystal plane structure stability,which led to the development of a highperformance,fast-charging sodium-ion battery(SIB),opening new avenues for commercial applications.展开更多
Manganese-catalyzed C—C bond cleavage of cyclobutanols has attracted great attention due to the high abundance and cheap and eco-friendly behaviour.A manganese-catalyzed ring-opening C—C bond fluorination of cyclobu...Manganese-catalyzed C—C bond cleavage of cyclobutanols has attracted great attention due to the high abundance and cheap and eco-friendly behaviour.A manganese-catalyzed ring-opening C—C bond fluorination of cyclobutanols is reported.Under mild conditions,the reaction provides a straightforward access to γ-fluorinated ketones using 10 mol% Mn(OAc)_(2) as catalyst and electrophilic fluorination reagent,which was generated in situ from HF·Et 3N and PhIO,as fluorine source.The reaction has an excellent functional-group tolerance and displays a broad substrate scope,affording the corresponding products in 50%~76%yields.展开更多
Surface fluorination of conventional polymers can give them desirable surface properties similar to the expensive and difficult-to-process fluoropolymers.However,traditional surface fluorination techniques often requi...Surface fluorination of conventional polymers can give them desirable surface properties similar to the expensive and difficult-to-process fluoropolymers.However,traditional surface fluorination techniques often require toxic reagents and special equipment.Here,we report a simple and effective polymer surface fluorination method by using safe and inexpensive perfluoro-2-methyl-3-pentanone(PFMP,C_(2)F_(5)C(=O)CF(CF_(3))_(2))and UV irradiation.This method is applicable to various polymer materials,and generates nanometer-thick fluorinated layer on the outermost surface,significantly changing their surface properties without changing the surface morphology.展开更多
Spinel-type cathodes are considered an optimal substitute for conventional layered oxide cathodes owing to their use of inexpensive and earth-abundant manganese as the redox-active element.Moreover,the introduction of...Spinel-type cathodes are considered an optimal substitute for conventional layered oxide cathodes owing to their use of inexpensive and earth-abundant manganese as the redox-active element.Moreover,the introduction of cation disorder can effectively suppress the detrimental two-phase reaction to realize high capacities in a wide voltage range.However,the continuous capacity decay during cycles has hindered the widespread application of these cathode materials.Inorganic fluorides exhibit excellent electrochemical stability at high voltage;therefore,in this study,the direct F2 gas reaction with a partially disordered spinel cathode(Li_(1.6)Mn_(1.6)O_(3.7)F_(0.3,)LMOF1.6)was initially applied to investigate the impacts of fluorination on the surface structure and electrochemical performances.The inorganic fluorinated layer,mainly containing LiF,was distributed uniformly on the surface of LMOF1.6nanoparticles after fluorination for an appropriate time without the turbulence caused by the valency of manganese cation,which improved the capacity retention and rate capability by the suppression of structural damage,parasitic reaction,and cation dissolution.The LMOF1.6cathode fluorinated for 0.5 h exhibited a capacity of283.6 mAh·g^(-1)at 50 mA·g^(-1)and an enhanced capacity retention of 29.6%after 50 cycles in the voltage range of1.5-4.8 V,as compared to the pristine LMOF1.6 with only27.9%capacity retention.展开更多
Experiments were carried out to investigate the influence of TiO2 surface fluorination on the photodegradation of a representative organic cationic compound, Methylene Blue （MB）. The eleetropositive MB shows poor ad...Experiments were carried out to investigate the influence of TiO2 surface fluorination on the photodegradation of a representative organic cationic compound, Methylene Blue （MB）. The eleetropositive MB shows poor adsorption on TiO2 surface; its degradation performs a HO. radical-mediated mechanism. In the F-modified system, the kinetic reaction rate enlarged more than 2.5 fold that was attributed mainly to the accumulating adsorption of MB and the increased photogenerated hole available on the F-modified TiO2 surface.展开更多
A series of binuclear nickel phenoxyiminato catalysts with different linkers and fluorine substituents were efficiently synthesized. Binuclear nickel catalysts with rigid linkers showed higher catalytic activity and t...A series of binuclear nickel phenoxyiminato catalysts with different linkers and fluorine substituents were efficiently synthesized. Binuclear nickel catalysts with rigid linkers showed higher catalytic activity and thermal stability in ethylene polymerization and produced polymers with higher molecular weight possibly due to the larger steric hindrance and metal-metal synergistic effect. The introduction of fluorine atoms on the N-terphenyl moity also enhanced polymerization activity and molecular weight of polymer due to the electronic effect of fluorine atoms.展开更多
Boron has a promising application in the field of propellants due to its high calorific value.However,the difficulty of ignition and the poor combustion efficiency of boron(B)have severely limited its efficient applic...Boron has a promising application in the field of propellants due to its high calorific value.However,the difficulty of ignition and the poor combustion efficiency of boron(B)have severely limited its efficient application.In response to this issue,this paper proposes to improve the ignition and combustion performance of micron-sized boron by the Polyvinylidene Fluoride(PVDF)coating.The effect of PVDF content on the B combustion performance was systematically studied using a Thermogravimetry-Differential Scanning Calorimetry(TG-DSC),a Transmission Electron Microscope(TEM),an X-Ray Diffractometer(XRD),a laser Particle Size Analyzer(PSA),and a high-speed camera.The results show that PVDF can significantly reduce the initial oxidation temperature of B powder and increase its reaction heat.When the PVDF content is 23wt%,the reaction heat and the combustion intensity of B powder reach the maximum and are significantly higher than those of the uncoated B powder.Moreover,the fluorination reaction that occurs during the combustion process not only can effectively shorten the combustion time of B powder,but also has a positive effect on its flame intensity and propagation speed,and it significantly reduces B particle agglomeration,which improves the combustion efficiency significantly.This study lays the foundation for the application of PVDF modified B in B-based solid propellants.展开更多
The fluorination reaction involving a β-ketosulfones by Selectfluor^TM was efficiently promoted by the ionic liquid, [Hbim]BF4 （IL） as a reaction medium with methanol as co-solvent at room temperature under ultraso...The fluorination reaction involving a β-ketosulfones by Selectfluor^TM was efficiently promoted by the ionic liquid, [Hbim]BF4 （IL） as a reaction medium with methanol as co-solvent at room temperature under ultrasonic irradiation to afford the corresponding mono and difluoro-β-ketosulfones in excellent yields. The advantages of this method include among others the use of a recyclable, non-volatile ionic liquid, which promotes this protocol under room temperature without the requirement of any added catalyst under ultrasonic irradiation.展开更多
The development of all-solid-state lithium batteries(ASSLBs)depends on exploiting solid-state electrolytes(SSEs)with high ionic conductivity and electrochemical stability.Fluorination is generally considered to be an ...The development of all-solid-state lithium batteries(ASSLBs)depends on exploiting solid-state electrolytes(SSEs)with high ionic conductivity and electrochemical stability.Fluorination is generally considered to be an effective strategy to improve the ionic conductivity and electrochemical stability of inorganic SSEs.Here,we report the partial fluorination of the chlo rine sites in an antiperovskite,by which the orthorhombic Li_(2)OHCl was transformed into cubic Li_(2)OHCl_(0.9)F_(0.1),resulting in a fourfold increase in ionic conductivity at 30℃.The ab initio molecular dynamics simulations suggest that both the crystal symmetry and the anions electronegativity influence the diffusion of Li+in the antiperovskite structure.Besides,from the perspective of experiments and calculations,it is confirmed that fluorination is a feasible method to improve the electrochemical stability of antiperovskite SSEs.The LiFePO_(4)|Li cell based on Li_(2)OHCl_(0.9)F_(0.1) is also assembled and exhibits stable cycle performance,which indicates that fluorination of antiperovskite SSEs is an effective way to produce high-performance SSEs for practical application of ASSLBs.展开更多
In this work,a technique was proposed to prepare UO_(2)from UO_(3)by the two processes of fluorination reaction of UO_(3)with NH_(4)HF_(2)and electrochemical reduction of UO_(2)^(2+)for the recycle uranium.The feasibi...In this work,a technique was proposed to prepare UO_(2)from UO_(3)by the two processes of fluorination reaction of UO_(3)with NH_(4)HF_(2)and electrochemical reduction of UO_(2)^(2+)for the recycle uranium.The feasibility of fluorination reaction was firstly confirmed using thermodynamic calculation;then,the products were analyzed using XRD,Raman and fluorescence to be UO_(2)F_(2).The fluorination mechanism was inferred to be UO_(3)(s)+NH_(4)HF_(2)→(NH_(4))_(3)UO_(2)F_(5)→NH_(4)(UO_(2))_(2)F_(5)→UO_(2)F_(2).The redox behavior of UO_(2)^(2+)on W electrode was investigated by cyclic voltammetry and square wave voltammetry,which indicated that UO_(2)^(2+) was reduced to UO_(2)via a two-step single electron transfer with diffusion-controlled.The diffusion coefficient of UO_(2)^(2+) was calculated to be 6.22×10^(-5)cm/s.The disproportionation reaction of UO_(2)^(+) was observed,and the relationship between the disproportionation reaction and scan rate was discussed.Moreover,the electrochemical fabrication of UO_(2) was conducted by electrolysis at-0.8 V,and the product was analyzed by XRD,SEM and EDS to be UO_(2).ICP-AES results showed that the extraction efficiency of UO_(2) could reach 98.53%.展开更多
Using PTFE as a chemical modifier, a method for the determination of trace impurities in high purity Nd_2O_3 by in-situ separation and electrothermal vaporization-inductively coupled plasma-atomic emission spectrometr...Using PTFE as a chemical modifier, a method for the determination of trace impurities in high purity Nd_2O_3 by in-situ separation and electrothermal vaporization-inductively coupled plasma-atomic emission spectrometry (ETV-ICP-AES) was developed. The analyte-matrix separation and the temperature program of graphite furnace were investigated and optimized. The solid samples were directly introduced into graphite furnace in the form of slurry, where selective volatilization between the matrix and the analytes took place. The Nd matrix was retained in the graphite furnace during the evaporation step, while the trace analyte impurities were vaporized and removed. As a result, the matrix interference that is serious without the modifier is suppressed effectively. The achievable detection limits are (μg·g^(-1)): Ti 0.15, Mn 0.15, Ni 0.20, Co 0.54, respectively. The proposed method was applied to direct determination of trace impurities in high purity Nd_2O_3 with satisfactory results.展开更多
The power conversion efficiencies(PCEs)of organic solar cells(OSCs)have reached 18%recently,which have already met the demand of practical application.However,these outstanding results were generally achieved with don...The power conversion efficiencies(PCEs)of organic solar cells(OSCs)have reached 18%recently,which have already met the demand of practical application.However,these outstanding results were generally achieved with donor-acceptor(D-A)type copolymer donors,which can hardly fulfill the low-cost largescale production due to their complicated synthesis processes.Therefore,developing polymer donors with simple chemical structures is urgent for realizing low-cost OSCs.Polythiophene(PT)derivatives are currently regarded as promising candidates for such kind of donor materials,which has been illustrated in many works.In this work,two new alkylthio substituted PT derivatives,P301 and P302,were synthesized and tested as donors in the OSCs using Y5 as the accepto r.In comparison,the introduction of fluorine atoms on the backbone of P302 can not only downshift the energy levels,but also greatly improve the phase separation morphologies of the active layers,which is ascribed to the enhanced aggregation effect and the reduced miscibility with the non-fullerene acceptor.As a result,the P302:Y5-based OSC exhibits a significantly improved PCE of 9.65%than that of P301:Y5-based one,indicating the important role of fluorination in the construction of efficient PT derivative donors.展开更多
Lithium(Li)metal anodes have attracted extensive attention due to their ultrahigh theoretical capacity and low potential.However,the uneven deposition of Li near the unstable electrode/electrolyte interfaces leads to ...Lithium(Li)metal anodes have attracted extensive attention due to their ultrahigh theoretical capacity and low potential.However,the uneven deposition of Li near the unstable electrode/electrolyte interfaces leads to the growth of Li dendrites and the degradation of active electrodes.Herein,we directly fluorinate alkyne-containing conjugated microporous polymers(ACMPs)microspheres with fluorine gas(F_(2))to introduce a novel fluorinated interlayer as an interfacial stabilizer in lithium metal batteries.Using density functional theory methods,it is found that as-prepared fluorinated ACMP(FACMP)has abundant partially ionic C–F bonds.The C–F bonds with electrochemical lability yield remarkable lithiophilicity during cycling.The in situ reactions between the active C–F bonds and Li ions enable transfer of lithium fluoride microcrystals to the solid electrolyte interphase(SEI)layers,guaranteeing effective ionic distribution and smooth Li deposition.Consequently,Li metal electrodes with the fluorinated interlayers demonstrate excellent cycling performances in both half-batteries and full cells with a lithium bis(trifluoromethanesulfonyl)imide electrolyte as well as a nonfluorinated lithium bis(oxalate)borate electrolyte system.This strategy is highly significant in customizable SEI layers to stabilize electrode interfaces and ensure high utilization of Li metal anodes,especially in a nonfluorinated electrolyte.展开更多
The effect of fluorination on the aggregate structure of a novel fluorinated perylene diimide, N, N'-diperfluorophenyl-3, 4, 9, 10-perylenetetracarboxylic diimide 1, was investigated by UV-Vis absorptions and the ...The effect of fluorination on the aggregate structure of a novel fluorinated perylene diimide, N, N'-diperfluorophenyl-3, 4, 9, 10-perylenetetracarboxylic diimide 1, was investigated by UV-Vis absorptions and the conformation simulations from AM1 semi-empirical quantum mechanics modeling. The results showed that in the solid film 1 molecules stacked with the perfluorinated phenyl groups straightly over or below the perylene cores of the adjacent 1 molecules.展开更多
A new method for direct determination of lanthanum in solid biological materials by fluorination electrothermal vaporization ICP-AES technique with polytetrafluoroethylene(PTFE)disperser as a fluorination agent has be...A new method for direct determination of lanthanum in solid biological materials by fluorination electrothermal vaporization ICP-AES technique with polytetrafluoroethylene(PTFE)disperser as a fluorination agent has been described.The effect of particle size on the signal intensity of La has been investigated.The vaporization behaviour of lanthanum and the main factors affecting fluorinating vaporization have been observed.Under optimum experimental conditions,the detection limit of La to this method is 2.0 ng/ml,and the RSD is 4.5%.The proposed method has been applied to determining directly trace lanthanum in solid biological standard reference materials without any chemical pretreatment,and the determined values are in good agreement with the certified ones.展开更多
基金supported in part by the National Natural Science Foundation of China under Grant 52277139 and 52367014in part by the Guangxi Science Fund for Distinguished Young Scholars under Grant 2024GXNSFFA999017.
文摘Fluorination is a critical surface modification technique for enhancing the electrical performance of composite insulators.This study employs molecular simulations to examine the microstructure and space charge behavior of fluorinated and non-fluorinated silicone rubber under an electric field,with experimental validation.The results show that fluorinated silicone rubber exhibits lower total energy,higher polarization,and stronger dipole moments compared to its non-fluorinated counterpart,shifting the material from an insulating to a conductive state.Under lower electric field strengths,the carbon-silicon bonds in fluorinated silicone rubber are longer,but it maintains geometric stability under higher fields.The energy gap changes across different fluorination modes and varies with electric field strength,indicating that fluorination affects conductivity differently at various field intensities.Both fluorination methods improve conductivity in the 0–3.8 V/nm range,with substitutional fluorination showing superior performance between 3.8 and 8.9 V/nm.Above 9.1 V/nm,fluorination maximizes conductivity.The fluorinated samples exhibit a greater redshift at higher electric fields,resulting in enhanced conductivity and improved surface charge distribution.These findings offer insights into the microscopic effects of fluorination on silicone rubber’s electrical properties,while experiments confirm that fluorination increases hydrophobicity and boosts DC flashover voltage,further enhancing the material’s performance.
基金financial support from the Marine S&T Fund of Shandong Province for Pilot National Laboratory for Marine Science and Technology(Qingdao)(No.2022QNLM030003-2)the National Natural Science Foundation of China(No.21977088)the National Natural Science Foundation of China-Shandong Joint Fund(No.U1906213)。
文摘Ag_(2)CO_(3)-promoted dehydroxymethylative fluorination of aliphatic alcohols has been achieved with Selectfluor as both oxidant and fluorine source.The reaction involvesβ-fragmentation of primary alkoxy radicals,followed by the fluorination of the resulting C-centered radical intermediates.The transformation proceeds under mild reaction conditions and exhibits a broad substrate scope,thus opening up a new entrance to the synthesis of fluorinated constructs includingα-fluoroimides and 1-fluoroalkyl benzoates as well as secondary and tertiary alkyl fluorides like versatile 2-fluoro-2-alkyl 1,3-propandiol derivatives.The divergent functionalization of the obtainedα-fluoroimides enables an efficient access to amine derivatives through C-F bond activation under the action of BF_(3)·OEt_(2).
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.
基金This research was made possible as a result of a generous grant from the Fundamental Research Funds for the Central Universities(Nos.2232024Y-01,2232024A-03)the National Science Fund for Excellent Young Scholars(No.22122101).
文摘Here we present a highly efficient protocol utilizing nickel-hydride hydrogen atom transfer catalysis for the regio-and enantioselective hydrofluorination of internal alkenes.This method efficiently assembles a wide array of enantioenrichedβ-fluoro amides with excellent regio-and enantioselectivity from internal unactivated alkenes.Mechanistic investigations suggest that this transformation proceeds via a NiHhydrogen atom transfer to alkene,followed by a stereoselective fluorine atom transfer process.The weak coordination effect of the tethered amide group is identified as a crucial factor governing the observed regio-and enantioselectivity.
基金supported by the A*STAR MTC Programmatic Project(No.M23L9b0052)the Indonesia-NTU Singapore Institute of Research for Sustainability and Innovation(INSPIRASI)(No.6635/E3/KL.02.02/2023)+2 种基金the Singapore NRF Singapore-China Flagship Program(No.023740-00001)the National Natural Science Foundation of China(Nos.11975043 and 11475300)the China Scholarship Council(No.202306460087)。
文摘High-voltage solid-state lithium-ion batteries(SSLIBs)have attracted considerable research attention in recent years due to their high-energy-density and superior safety characteristics.However,the integration of high-voltage cathodes with solid electrolytes(SEs)presents multiple challenges,including the formation of high-impedance layers from spontaneous chemical reactions,electrochemical instability,insufficient interfacial contact,and lattice expansion.These issues significantly impair battery performance and potentially lead to battery failure,thus impeding the commercialization of high-voltage SSLIBs.The incorporation of fluorides,known for their robust bond strength and high free energy of formation,has emerged as an effective strategy to address these challenges.Fluorinated electrolytes and electrode/electrolyte interfaces have been demonstrated to significantly influence the reaction reversibility/kinetics,safety,and stability of rechargeable batteries,particularly under high voltage.This review summarizes recent advancements in fluorination treatment for high-voltage SEs,focusing on solid polymer electrolytes(SPEs),inorganic solid electrolytes(ISEs),and composite solid electrolytes(CSEs),along with the performance enhancements these strategies afford.This review aims to provide a comprehensive understanding of the structure-property relationships,the characteristics of fluorinated interfaces,and the application of fluorinated SEs in high-voltage SSLIBs.Further,the impacts of residual moisture and the challenges of fluorinated SEs are discussed.Finally,the review explores potential future directions for the development of fluorinated SSLIBs.
基金supported by the National Natural Science Foundation of China(Nos.22178221,22208221)the Shenzhen Science and Technology Program(Nos.JCYJ20220818095805012,JCYJ20230808105109019)+2 种基金the Natural Science Foundation of Guangdong Province(Nos.2024A1515011078,2024A1515011507)the Scientific Foundation for Youth Scholars of Shenzhen University(868-000001032522,827-0001004)the Instrumental Analysis Center of Shenzhen University for the assistance with the Electron Microscope technical support。
文摘To advance the application of layered oxide cathodes in fast-charging sodium-ion batteries,it is crucial to not only suppress irreversible phase transitions but also improve the rate capability of cathode materials and optimize Na^(+)diffusion kinetics to ensure high capacity output at various charge-discharge rates.In this research,the targeted F-substitution with a heavy ratio in oxygen anion layer optimizes the Na^(+)diffusion path and electronic conductivity of the material,thereby decreasing the Na^(+)diffusion barrier and imparting high-rate performance.At a 20 C rate,the cathode achieves a capacity of over 80 mAh g^(-1)with stable cycling performance.Additionally,the dual rivet effect between the transition metal layer and oxygen layer prevents significant phase transitions during charge/discharge within the 2-4.2 V range for the modified cathode.As a result,the F-substituted oxygen anion layer improved Na^(+)diffusion,electronic conductivity,and crystal plane structure stability,which led to the development of a highperformance,fast-charging sodium-ion battery(SIB),opening new avenues for commercial applications.
基金Project supported by the National Natural Science Foundation of China(Nos.92156008,22161142016)the Taishan Scholar Program at Shandong Provincethe Natural Science Foundation of Shandong Province(No.ZR2020QB018)。
文摘Manganese-catalyzed C—C bond cleavage of cyclobutanols has attracted great attention due to the high abundance and cheap and eco-friendly behaviour.A manganese-catalyzed ring-opening C—C bond fluorination of cyclobutanols is reported.Under mild conditions,the reaction provides a straightforward access to γ-fluorinated ketones using 10 mol% Mn(OAc)_(2) as catalyst and electrophilic fluorination reagent,which was generated in situ from HF·Et 3N and PhIO,as fluorine source.The reaction has an excellent functional-group tolerance and displays a broad substrate scope,affording the corresponding products in 50%~76%yields.
基金supported by internal fund from Tsinghua University.
文摘Surface fluorination of conventional polymers can give them desirable surface properties similar to the expensive and difficult-to-process fluoropolymers.However,traditional surface fluorination techniques often require toxic reagents and special equipment.Here,we report a simple and effective polymer surface fluorination method by using safe and inexpensive perfluoro-2-methyl-3-pentanone(PFMP,C_(2)F_(5)C(=O)CF(CF_(3))_(2))and UV irradiation.This method is applicable to various polymer materials,and generates nanometer-thick fluorinated layer on the outermost surface,significantly changing their surface properties without changing the surface morphology.
基金financially supported by the National Key R and D Program of China(No.2022YFB3805702)State Key Program of the National Natural Science Foundation of China(No.52130303)+1 种基金National Natural Science Foundation of China(Nos.51973152,51973119,5210309352173078)。
文摘Spinel-type cathodes are considered an optimal substitute for conventional layered oxide cathodes owing to their use of inexpensive and earth-abundant manganese as the redox-active element.Moreover,the introduction of cation disorder can effectively suppress the detrimental two-phase reaction to realize high capacities in a wide voltage range.However,the continuous capacity decay during cycles has hindered the widespread application of these cathode materials.Inorganic fluorides exhibit excellent electrochemical stability at high voltage;therefore,in this study,the direct F2 gas reaction with a partially disordered spinel cathode(Li_(1.6)Mn_(1.6)O_(3.7)F_(0.3,)LMOF1.6)was initially applied to investigate the impacts of fluorination on the surface structure and electrochemical performances.The inorganic fluorinated layer,mainly containing LiF,was distributed uniformly on the surface of LMOF1.6nanoparticles after fluorination for an appropriate time without the turbulence caused by the valency of manganese cation,which improved the capacity retention and rate capability by the suppression of structural damage,parasitic reaction,and cation dissolution.The LMOF1.6cathode fluorinated for 0.5 h exhibited a capacity of283.6 mAh·g^(-1)at 50 mA·g^(-1)and an enhanced capacity retention of 29.6%after 50 cycles in the voltage range of1.5-4.8 V,as compared to the pristine LMOF1.6 with only27.9%capacity retention.
文摘Experiments were carried out to investigate the influence of TiO2 surface fluorination on the photodegradation of a representative organic cationic compound, Methylene Blue （MB）. The eleetropositive MB shows poor adsorption on TiO2 surface; its degradation performs a HO. radical-mediated mechanism. In the F-modified system, the kinetic reaction rate enlarged more than 2.5 fold that was attributed mainly to the accumulating adsorption of MB and the increased photogenerated hole available on the F-modified TiO2 surface.
基金financially supported by the National Natural Science Foundation of China (No. 51573002)
文摘A series of binuclear nickel phenoxyiminato catalysts with different linkers and fluorine substituents were efficiently synthesized. Binuclear nickel catalysts with rigid linkers showed higher catalytic activity and thermal stability in ethylene polymerization and produced polymers with higher molecular weight possibly due to the larger steric hindrance and metal-metal synergistic effect. The introduction of fluorine atoms on the N-terphenyl moity also enhanced polymerization activity and molecular weight of polymer due to the electronic effect of fluorine atoms.
基金financial support provided by the National Natural Science Foundation of China (No.52376093)the Project of Jiangsu Graduate Practice Innovation,China (Nos. SJCX22_1435 and SJCX22_1436)sponsored by Qing Lan Project of Jiangsu Province,China.
文摘Boron has a promising application in the field of propellants due to its high calorific value.However,the difficulty of ignition and the poor combustion efficiency of boron(B)have severely limited its efficient application.In response to this issue,this paper proposes to improve the ignition and combustion performance of micron-sized boron by the Polyvinylidene Fluoride(PVDF)coating.The effect of PVDF content on the B combustion performance was systematically studied using a Thermogravimetry-Differential Scanning Calorimetry(TG-DSC),a Transmission Electron Microscope(TEM),an X-Ray Diffractometer(XRD),a laser Particle Size Analyzer(PSA),and a high-speed camera.The results show that PVDF can significantly reduce the initial oxidation temperature of B powder and increase its reaction heat.When the PVDF content is 23wt%,the reaction heat and the combustion intensity of B powder reach the maximum and are significantly higher than those of the uncoated B powder.Moreover,the fluorination reaction that occurs during the combustion process not only can effectively shorten the combustion time of B powder,but also has a positive effect on its flame intensity and propagation speed,and it significantly reduces B particle agglomeration,which improves the combustion efficiency significantly.This study lays the foundation for the application of PVDF modified B in B-based solid propellants.
文摘The fluorination reaction involving a β-ketosulfones by Selectfluor^TM was efficiently promoted by the ionic liquid, [Hbim]BF4 （IL） as a reaction medium with methanol as co-solvent at room temperature under ultrasonic irradiation to afford the corresponding mono and difluoro-β-ketosulfones in excellent yields. The advantages of this method include among others the use of a recyclable, non-volatile ionic liquid, which promotes this protocol under room temperature without the requirement of any added catalyst under ultrasonic irradiation.
基金supported by the National Key Research and Development Program of China(2020YFA0210701)the National Natural Science Foundation of China(22005134,12275119,U22A20439)+4 种基金the Shenzhen Science and Technology Program(RCBS20210609103647030)the Guangdong Basic and Applied Basic Research Foundation(2021A1515012403)the Shenzhen Science and Technology Program(KQTD20200820113047086)the Guangdong-Hong Kong-Macao Joint Laboratory for PhotonicThermal-Electrical Energy Materials and Devices(2019B121205001)the open research fund of Songshan Lake Materials Laboratory(2022SLABFK04)。
文摘The development of all-solid-state lithium batteries(ASSLBs)depends on exploiting solid-state electrolytes(SSEs)with high ionic conductivity and electrochemical stability.Fluorination is generally considered to be an effective strategy to improve the ionic conductivity and electrochemical stability of inorganic SSEs.Here,we report the partial fluorination of the chlo rine sites in an antiperovskite,by which the orthorhombic Li_(2)OHCl was transformed into cubic Li_(2)OHCl_(0.9)F_(0.1),resulting in a fourfold increase in ionic conductivity at 30℃.The ab initio molecular dynamics simulations suggest that both the crystal symmetry and the anions electronegativity influence the diffusion of Li+in the antiperovskite structure.Besides,from the perspective of experiments and calculations,it is confirmed that fluorination is a feasible method to improve the electrochemical stability of antiperovskite SSEs.The LiFePO_(4)|Li cell based on Li_(2)OHCl_(0.9)F_(0.1) is also assembled and exhibits stable cycle performance,which indicates that fluorination of antiperovskite SSEs is an effective way to produce high-performance SSEs for practical application of ASSLBs.
基金financially supported by the National Natural Science foundation of China(Nos.U2167215,22076035,21876034,11875116 and 21790373)the Fundamental Research Funds for the Central Universities(No.3072021CFJ1001)。
文摘In this work,a technique was proposed to prepare UO_(2)from UO_(3)by the two processes of fluorination reaction of UO_(3)with NH_(4)HF_(2)and electrochemical reduction of UO_(2)^(2+)for the recycle uranium.The feasibility of fluorination reaction was firstly confirmed using thermodynamic calculation;then,the products were analyzed using XRD,Raman and fluorescence to be UO_(2)F_(2).The fluorination mechanism was inferred to be UO_(3)(s)+NH_(4)HF_(2)→(NH_(4))_(3)UO_(2)F_(5)→NH_(4)(UO_(2))_(2)F_(5)→UO_(2)F_(2).The redox behavior of UO_(2)^(2+)on W electrode was investigated by cyclic voltammetry and square wave voltammetry,which indicated that UO_(2)^(2+) was reduced to UO_(2)via a two-step single electron transfer with diffusion-controlled.The diffusion coefficient of UO_(2)^(2+) was calculated to be 6.22×10^(-5)cm/s.The disproportionation reaction of UO_(2)^(+) was observed,and the relationship between the disproportionation reaction and scan rate was discussed.Moreover,the electrochemical fabrication of UO_(2) was conducted by electrolysis at-0.8 V,and the product was analyzed by XRD,SEM and EDS to be UO_(2).ICP-AES results showed that the extraction efficiency of UO_(2) could reach 98.53%.
文摘Using PTFE as a chemical modifier, a method for the determination of trace impurities in high purity Nd_2O_3 by in-situ separation and electrothermal vaporization-inductively coupled plasma-atomic emission spectrometry (ETV-ICP-AES) was developed. The analyte-matrix separation and the temperature program of graphite furnace were investigated and optimized. The solid samples were directly introduced into graphite furnace in the form of slurry, where selective volatilization between the matrix and the analytes took place. The Nd matrix was retained in the graphite furnace during the evaporation step, while the trace analyte impurities were vaporized and removed. As a result, the matrix interference that is serious without the modifier is suppressed effectively. The achievable detection limits are (μg·g^(-1)): Ti 0.15, Mn 0.15, Ni 0.20, Co 0.54, respectively. The proposed method was applied to direct determination of trace impurities in high purity Nd_2O_3 with satisfactory results.
基金the financial support from the Basic and Applied Basic Research Major Program of Guangdong Province(No.2019B030302007)the National Natural Science Foundation of China(Nos.21835006,91633301 and 22075017)+1 种基金the Fundamental Research Funds for the Central Universities,China(No.FRF-TP-19-047A2)Beijing National Laboratory for Molecular Sciences(No.BNLMS-CXXM-201903)。
文摘The power conversion efficiencies(PCEs)of organic solar cells(OSCs)have reached 18%recently,which have already met the demand of practical application.However,these outstanding results were generally achieved with donor-acceptor(D-A)type copolymer donors,which can hardly fulfill the low-cost largescale production due to their complicated synthesis processes.Therefore,developing polymer donors with simple chemical structures is urgent for realizing low-cost OSCs.Polythiophene(PT)derivatives are currently regarded as promising candidates for such kind of donor materials,which has been illustrated in many works.In this work,two new alkylthio substituted PT derivatives,P301 and P302,were synthesized and tested as donors in the OSCs using Y5 as the accepto r.In comparison,the introduction of fluorine atoms on the backbone of P302 can not only downshift the energy levels,but also greatly improve the phase separation morphologies of the active layers,which is ascribed to the enhanced aggregation effect and the reduced miscibility with the non-fullerene acceptor.As a result,the P302:Y5-based OSC exhibits a significantly improved PCE of 9.65%than that of P301:Y5-based one,indicating the important role of fluorination in the construction of efficient PT derivative donors.
基金Science Foundation for Distinguished Young Scholars in Tianjin,Grant/Award Number:19JCJQJC61700National Natural Science Foundation of China,Grant/Award Numbers:51773147,51973151,52130303National Key R&D Program of China,Grant/Award Number:2022YFB3805702。
文摘Lithium(Li)metal anodes have attracted extensive attention due to their ultrahigh theoretical capacity and low potential.However,the uneven deposition of Li near the unstable electrode/electrolyte interfaces leads to the growth of Li dendrites and the degradation of active electrodes.Herein,we directly fluorinate alkyne-containing conjugated microporous polymers(ACMPs)microspheres with fluorine gas(F_(2))to introduce a novel fluorinated interlayer as an interfacial stabilizer in lithium metal batteries.Using density functional theory methods,it is found that as-prepared fluorinated ACMP(FACMP)has abundant partially ionic C–F bonds.The C–F bonds with electrochemical lability yield remarkable lithiophilicity during cycling.The in situ reactions between the active C–F bonds and Li ions enable transfer of lithium fluoride microcrystals to the solid electrolyte interphase(SEI)layers,guaranteeing effective ionic distribution and smooth Li deposition.Consequently,Li metal electrodes with the fluorinated interlayers demonstrate excellent cycling performances in both half-batteries and full cells with a lithium bis(trifluoromethanesulfonyl)imide electrolyte as well as a nonfluorinated lithium bis(oxalate)borate electrolyte system.This strategy is highly significant in customizable SEI layers to stabilize electrode interfaces and ensure high utilization of Li metal anodes,especially in a nonfluorinated electrolyte.
文摘The effect of fluorination on the aggregate structure of a novel fluorinated perylene diimide, N, N'-diperfluorophenyl-3, 4, 9, 10-perylenetetracarboxylic diimide 1, was investigated by UV-Vis absorptions and the conformation simulations from AM1 semi-empirical quantum mechanics modeling. The results showed that in the solid film 1 molecules stacked with the perfluorinated phenyl groups straightly over or below the perylene cores of the adjacent 1 molecules.
基金supported by the National Natural Science Foundation of China.
文摘A new method for direct determination of lanthanum in solid biological materials by fluorination electrothermal vaporization ICP-AES technique with polytetrafluoroethylene(PTFE)disperser as a fluorination agent has been described.The effect of particle size on the signal intensity of La has been investigated.The vaporization behaviour of lanthanum and the main factors affecting fluorinating vaporization have been observed.Under optimum experimental conditions,the detection limit of La to this method is 2.0 ng/ml,and the RSD is 4.5%.The proposed method has been applied to determining directly trace lanthanum in solid biological standard reference materials without any chemical pretreatment,and the determined values are in good agreement with the certified ones.
