High-entropy catalysts featuring exceptional properties are,in no doubt,playing an increasingly significant role in aprotic lithium-oxygen batteries.Despite extensive effort devoted to tracing the origin of their unpa...High-entropy catalysts featuring exceptional properties are,in no doubt,playing an increasingly significant role in aprotic lithium-oxygen batteries.Despite extensive effort devoted to tracing the origin of their unparalleled performance,the relationships between multiple active sites and reaction intermediates are still obscure.Here,enlightened by theoretical screening,we tailor a high-entropy perovskite fluoride(KCoMnNiMgZnF_(3)-HEC)with various active sites to overcome the limitations of conventional catalysts in redox process.The entropy effect modulates the d-band center and d orbital occupancy of active centers,which optimizes the d–p hybridization between catalytic sites and key intermediates,enabling a moderate adsorption of LiO_(2)and thus reinforcing the reaction kinetics.As a result,the Li–O2 battery with KCoMnNiMgZnF_(3)-HEC catalyst delivers a minimal discharge/charge polarization and long-term cycle stability,preceding majority of traditional catalysts reported.These encouraging results provide inspiring insights into the electron manipulation and d orbital structure optimization for advanced electrocatalyst.展开更多
With the recent development of high entropy materials, an alternative approach to develop advanced functional materials with distinctive properties that show improved values compared to conventional materials has been...With the recent development of high entropy materials, an alternative approach to develop advanced functional materials with distinctive properties that show improved values compared to conventional materials has been provided. The high entropy concept was later successfully transferred to metal fluorides and high entropy fluorides(HEFs) were successfully synthesized. Owing to their high theoretical specific capacities in energy storage applications, HEFs were utilized as cathode materials for lithiumion batteries(LIBs) and their underlying storage mechanisms were investigated. Instead of a step-bystep reduction of each individual metal cation, the HEFs seem to exhibit a single-step reduction process,indicating a solid solution compound instead of merely a mixture of different metal fluorides. It was also observed that the electrochemical behavior of the HEFs depends on each individual incorporated element. Therefore, by altering the elemental composition, new materials that exhibit improved electrochemical properties can be designed. Remarkably, HEFs with seven incorporated metal elements exhibited a better cycling stability as well as a lower hysteresis compared to binary metal fluorides.These findings offer new guidelines for material design and tailoring towards high performance LIBs.展开更多
Organic-dispersible lanthanide fluorides nanocrystals were synthesized at a large scale using colloid-extraction method, in the presence of dialkyl-dithiophosphinic acid (DDPA) as the extraction agent. The products we...Organic-dispersible lanthanide fluorides nanocrystals were synthesized at a large scale using colloid-extraction method, in the presence of dialkyl-dithiophosphinic acid (DDPA) as the extraction agent. The products were characterized by means of X-ray powder diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and Fourier transformation infrared (FTIR) spectroscopy. It was found that the synthesized lanthanide fluorides nanoparticles had high purity and crystallinity, and could be well dispersed in organic solvents such as chloroform, toluene etc., which could be closely related to the surface-capping of the nanocrystals by the DDPA molecules. Moreover, the nanocrystals before and after extraction by DDPA showed few differences in the microscopic morphologies. It was implied that DDPA as the extraction agent had good protection to the nanocrystals as well, which could be essential to the commercial application of the titled rare earth nanocrystals as novel multifunctional additives in the fields of lubrication.展开更多
Fluoride nanoparticles with multiform crystal structures and morphologies were successfully synthesized by a facile, effective, and environmentally friendly coprecipitation method. Transmission electron microscopy (TE...Fluoride nanoparticles with multiform crystal structures and morphologies were successfully synthesized by a facile, effective, and environmentally friendly coprecipitation method. Transmission electron microscopy (TEM) was used to characterize the nanoparticles. The nanoparticles were modified by PEI, CTAB, PAA and Ci, respectively. It was feasible for function by -COOH and -NH2 groups, due to the surface modification. Moreover, different surface modifications of the nanoparticles were examined. The possible formation mechanisms for fluoride nanoparticles with surface modification were presented in detail. More importantly, it is expected to be widely applied to biomedicine.展开更多
The thermodynamic and dynamic behaviour of Ni<sup>2+</sup>|Ni couple in FLINAK melt is investigated by us-ing EMF measurement and micropolarization method.The couple shows the Nernstian reversibility and a...The thermodynamic and dynamic behaviour of Ni<sup>2+</sup>|Ni couple in FLINAK melt is investigated by us-ing EMF measurement and micropolarization method.The couple shows the Nernstian reversibility and alarge exchange current density(6 mA·cm<sup>-2</sup>).A single crystal LaF<sub>3</sub> which is a fluoride ion conductor usedas a membrane of the Ni<sup>2+</sup>|Ni couple reference electrode is reliable in FLINAK melts at 973 K.The poten-tial of LaF<sub>3</sub> membrane reference electrode is constant within±2 mV.The boron nitride used as a saltbridge was not good in FLINAK melts.The platinum electrode is studied by using micropolarization.Theequilibrium potential of Pt electrode is dependent on the absorption and the electrochemical reaction.Thepotential is stable for a constant composition at constant temperature.展开更多
An experimental device is constructed for measuring the density and liquidus temperature of molten fluorides by using the Archimedean and cooling curve methods respectively.Its operation is tested by measuring the den...An experimental device is constructed for measuring the density and liquidus temperature of molten fluorides by using the Archimedean and cooling curve methods respectively.Its operation is tested by measuring the density and liquidus temperature of NaCl salt.The accuracy of the liquidus temperature measurement is about±1 K.The density of NaCl measured is in good agreement with the widely recognized data and the deviation is less than 0.2%.The liquidus temperature and density of a typical heat transfer fluoride LiF-NaF-KF(46.5-11.5-42mol%)are investigated.展开更多
The lattice sites occupied by samarmm ions in KMgF<sub>3</sub> were ascertained The relationship be-tween valent state of samarium ion in hosts and substituted lattice sites was mvestigated using fluoresce...The lattice sites occupied by samarmm ions in KMgF<sub>3</sub> were ascertained The relationship be-tween valent state of samarium ion in hosts and substituted lattice sites was mvestigated using fluorescentspectra.It is found that the valent state of samarium in different cationic lattice sites is different The internalrelation between the valent state of samarium ion and occupied lattice site was展开更多
For developing coating materials, the fluorides of scandium, lanthanum, strontium, barium, magnesium and aluminum were produced from their oxides and chlorides by means of exposure to chlorine trifluoride gas at tempe...For developing coating materials, the fluorides of scandium, lanthanum, strontium, barium, magnesium and aluminum were produced from their oxides and chlorides by means of exposure to chlorine trifluoride gas at temperatures between room temperature and 700°C. The metal chlorides could be easily fluorinated even at room temperature, while the metal oxides required temperatures higher than 300?C. After the heating in ambient hydrogen at 1100°C, the fluorides of lanthanum and barium showed very low weight losses at 1100°C, although the weights of the other fluorides significantly decreased. These materials may work as protective films against corrosive and high temperature environments, particularly when using the chlorine trifluoride gas.展开更多
A nickel-catalyzed direct hydromonofluoromethylation of unactivated olefins with industrial raw fluoroiodomethane is developed,furnishing various primary alkyl fluorides in a step-economic manner.The key factor to suc...A nickel-catalyzed direct hydromonofluoromethylation of unactivated olefins with industrial raw fluoroiodomethane is developed,furnishing various primary alkyl fluorides in a step-economic manner.The key factor to success is the use of pyridine-oxazoline as ligand and(MeO)_(2)MeSiH as the hydrogen source.This transformation demonstrates high efficiency,mild conditions,good functional-group compatibility and great potential in the drug discovery.展开更多
L-Hexoses are key components of many biologically relevant natural products and pharmaceuticals.As rare sugars,L-hexoses are not readily obtained from natural sources.Access to L-hexose building blocks from commercial...L-Hexoses are key components of many biologically relevant natural products and pharmaceuticals.As rare sugars,L-hexoses are not readily obtained from natural sources.Access to L-hexose building blocks from commercially available and inexpensive D-sugars is highly desirable from the viewpoints of organic synthesis and drug discovery.As demonstrated by the convenient preparation of L-glucosyl,L-galactosyl,and L-mannosyl fluorides from readily availableβ-D-C-glucosyl,β-D-C-mannosyl,andβ-D-C-galactosyl derivatives,we describe a novel and efficient approach to the demanding L-glycosyl fluorides.展开更多
A practical one-pot preparation of carbamoyl fluorides from easily obtained pyridine N-oxide,commercially available secondary amines and synthetically versatile difluorocarbene precursors(Ruppert-Prakash reagent or Ch...A practical one-pot preparation of carbamoyl fluorides from easily obtained pyridine N-oxide,commercially available secondary amines and synthetically versatile difluorocarbene precursors(Ruppert-Prakash reagent or Chen's reagent)was developed herein,which dexterously resorted to the oxidation of difluorocarbene by external pyridine N-oxide to produce the toxic and gaseous fluorophosgene in situ.Notable features of this method include nice functionality tolerance,late-stage modification of drug molecules and the recoveryand recycle of quinoline.展开更多
Potassium ion capacitors(PICs)are regarded as promising large-scale aqueous energy storage systems.However,due to the poor K^(+)transport kinetics and the structural instability of the cathode materials,the key issues...Potassium ion capacitors(PICs)are regarded as promising large-scale aqueous energy storage systems.However,due to the poor K^(+)transport kinetics and the structural instability of the cathode materials,the key issues of limited energy density and poor cyclic stability are obstacles to the in-depth growth of PICs.Herein,a novel O-doped perovskite fluoride is demonstrated via an in-situ electrochemical oxidation strategy as the cathode for PICs,introducing additional defects that improve the capacitance and facilitate the reaction kinetics of the electrode.During the electrochemical oxidation process,it is discovered that the perovskite fluoride crystal tends to transform into disordered O-doped KMnF 3(K_(x)MnF_(y)O_(z)),realizing a structural reconstruction at the electrode material/electrolyte interface.The First-principles calculations based on density functional theory(DFT)are performed to confirm that the improved electrical conduc-tivity and low ionic adsorption energy may be ascribed to the substitution of oxygen for fluorine.The obtained K_(1.14)MnF_(1.17)O_(1.26) cathode achieves a high specific capacitance of 694 F g^(-1) at 1 A g^(-1),as well as high capacitance retention of 91.3%after 10,000 charge/discharge cycles in mild K_(2)SO_(4) electrolyte.This study provides an effective strategy to improve the capacitive performance of perovskite fluoride cathode materials in electrochemical energy storage.展开更多
The recent results on hydrothermal synthesis of mixed rare earth-alkali or ammonium fluorides were presented. The initial ratios of the starting materials, pH value and reaction temperature were the critical factors f...The recent results on hydrothermal synthesis of mixed rare earth-alkali or ammonium fluorides were presented. The initial ratios of the starting materials, pH value and reaction temperature were the critical factors for obtaining the single-phase product. Four main types of complex rare earth fluorides, AREF4, A2REF5, ARE2F7 and ARE3F10 (A=Na+, K+, Rb+, NH4+), appeared in the primary hydrothermal reactions. The correlation between cation sizes and the formation of mixed rare earth fluorides under mild hydrothermal condition was given.展开更多
Since the sulfur(Ⅵ)fluoride exchange reaction(SuFEx)was introduced by Sharpless and co-workers in 2014,this new-generation click chemistry has emerged as an efficient and reliable tool for creating modular intermolec...Since the sulfur(Ⅵ)fluoride exchange reaction(SuFEx)was introduced by Sharpless and co-workers in 2014,this new-generation click chemistry has emerged as an efficient and reliable tool for creating modular intermolecular connections.Sulfonyl fluorides,one of the most important sulfur(Ⅵ)fluoride species,have attracted enormous attention in diverse fields,ranging from organic synthesis and material science,to chemical biology and drug discovery.This review aims to introduce seminal and recent progresses on the synthetic methods of sulfonyl fluorides,which include aromatic,aliphatic,alkenyl,and alkynyl sulfonyl fluorides.While not meant to be exhaustive,the purpose is to give a timely overview and insight in this field,and stimulate the development of more efficient synthetic methods of sulfonyl fluorides.展开更多
Hydrofluoride is an industry-preferred fluoride source,and finds extensively application to manufacture diverse fluoro chemicals.The Et3N-3HF complex is a liquid HF with improve safety.In this work,we report electroch...Hydrofluoride is an industry-preferred fluoride source,and finds extensively application to manufacture diverse fluoro chemicals.The Et3N-3HF complex is a liquid HF with improve safety.In this work,we report electrochemical synthesis of a series of sulfonyl fluoride with Et3N-3HF as fluoride source.The sulfinic salt is a smell-less,non-volatile,and air-stable sulfur source in this reaction.With the combination of Et3N-3HF and aryl/alkyl sulfinic salt,the sulfonyl fluorides are achieved without the use of external oxidant.In addition,we demonstrate further advantage in a tandem reaction involving Pd-catalyzed C—S cross-coupling and formation of S—F bond.A variety of functional groups including amino acids,heterocycles,halides are well tolerated.展开更多
Fluoride and nitrate enriched groundwater are potential threats to the safety of the groundwater supply that may cause significant effects on human health and public safety,especially in aggregated population areas an...Fluoride and nitrate enriched groundwater are potential threats to the safety of the groundwater supply that may cause significant effects on human health and public safety,especially in aggregated population areas and economic hubs.This study focuses on the high F^(−)and NO_(3)^(−)concentration groundwater in Tongzhou District,Beijing,North China.A total of 36 groundwater samples were collected to analyze the hydrochemical characteristics,elucidate genetic mechanisms and evaluate the potential human health risks.The results of the analysis indicate:Firstly,most of the groundwater samples are characterized by Mg-HCO_(3) and Na-HCO_(3) with the pH ranging from 7.19 to 8.28 and TDS with a large variation across the range 471-2337 mg/L.The NO_(3)^(−)concentration in 38.89%groundwater samples and the F^(−)concentration in 66.67%groundwater samples exceed the permissible limited value.Secondly,F^(−)in groundwater originates predominantly from water-rock interactions and the fluorite dissolution,which is also regulated by cation exchange,competitive adsorption of HCO_(3)−and an alkaline environment.Thirdly,the effect of sewage disposal and agricultural activities have a significant effect on high NO3-concentration,while the high F^(−)concentration is less influenced by anthropogenic activity.The alkaline environment favors nitrification,thus being conducive to the production of NO_(3)^(−).Finally,the health risk assessment is evaluated for different population groups.The results indicate that high NO_(3)^(−)and F^(−)concentration in groundwater would have the largest threat to children’s health.The findings of this study could contribute to the provision of a scientific basis for groundwater supply policy formulation relating to public health in Tongzhou District.展开更多
The quality upgrading and deashing of inferior coal by chemical method still faces great challenges.The dangers of strong acid,strong alkali,waste water and exhaust gas as well as high cost limit its industrial produc...The quality upgrading and deashing of inferior coal by chemical method still faces great challenges.The dangers of strong acid,strong alkali,waste water and exhaust gas as well as high cost limit its industrial production.This paper systematically investigates the ash reduction and desilicification of two typical inferior coal utilizing ammonium fluoride roasting method.Under the optimal conditions,for fat coal and gas coal,the deashing rates are 69.02%and 54.13%,and the desilicification rates are 92.64%and 90.27%,respectively.The molar dosage of ammonium fluoride remains consistent for both coals;however,the gas coal,characterized by a lower ash and silica content(less than half that of the fat coal),achieves optimum deashing effect at a reduced time and temperature.The majority of silicon in coal transforms into gaseous ammonium fluorosilicate,subsequently preparing nanoscale amorphous silica with a purity of 99.90%through ammonia precipitation.Most of the fluorine in deashed coal are assigned in inorganic minerals,suggesting the possibility of further fluorine and ash removal via flotation.This research provides a green and facile route to deash inferior coal and produce nano-scale white carbon black simultaneously.展开更多
Eu<sup>2+</sup> and Ce<sup>3+</sup> are important rare earth ions with variable valences. There existtwo kind of transition emission, d-f and f-f for Eu<sup>2+</sup>. Eu<sup>2...Eu<sup>2+</sup> and Ce<sup>3+</sup> are important rare earth ions with variable valences. There existtwo kind of transition emission, d-f and f-f for Eu<sup>2+</sup>. Eu<sup>2+</sup> is a good candidatefor the activators of UV-visible tunable laser and luminescent materials due to itstransition characteristics. Ce<sup>3+</sup> displays only d-f transition, which is different fromother rare earth ions. Because of the transition properties of Eu<sup>2+</sup> and Ce<sup>3+</sup>, theyare used both as good activators and as efficient sensitizers. Spectral展开更多
基金P.G.acknowledges the financial support from the Youth Foundation of Shandong Natural Science Foundation(No.ZR2023OB230)National Natural Science Foundation(No.22309035)Double First-class Discipline Construction Fund Project of Harbin Institute of Technology at Weihai(No.2023SYLHY11).
文摘High-entropy catalysts featuring exceptional properties are,in no doubt,playing an increasingly significant role in aprotic lithium-oxygen batteries.Despite extensive effort devoted to tracing the origin of their unparalleled performance,the relationships between multiple active sites and reaction intermediates are still obscure.Here,enlightened by theoretical screening,we tailor a high-entropy perovskite fluoride(KCoMnNiMgZnF_(3)-HEC)with various active sites to overcome the limitations of conventional catalysts in redox process.The entropy effect modulates the d-band center and d orbital occupancy of active centers,which optimizes the d–p hybridization between catalytic sites and key intermediates,enabling a moderate adsorption of LiO_(2)and thus reinforcing the reaction kinetics.As a result,the Li–O2 battery with KCoMnNiMgZnF_(3)-HEC catalyst delivers a minimal discharge/charge polarization and long-term cycle stability,preceding majority of traditional catalysts reported.These encouraging results provide inspiring insights into the electron manipulation and d orbital structure optimization for advanced electrocatalyst.
基金the financial support received from the China Scholarship Council(CSC)MERAGEM graduate school and the Ministry of Science,Research and Arts of the State of Baden-Wu rttemberg for funding research+4 种基金the support of the German Research Foundation(DFG)project(SE 1407/4-2)the support of the En ABLES,a project funded by the European Union’s Horizon 2020 research and innovation program under grant agreement(730957)the support of Epi Store project under grant agreement(101017709)the Centre for Electrochemical Energy Storage Ulm-Karlsruhe(CELEST)the support from the Karlsruhe Nano Micro Facility(KNMF)。
文摘With the recent development of high entropy materials, an alternative approach to develop advanced functional materials with distinctive properties that show improved values compared to conventional materials has been provided. The high entropy concept was later successfully transferred to metal fluorides and high entropy fluorides(HEFs) were successfully synthesized. Owing to their high theoretical specific capacities in energy storage applications, HEFs were utilized as cathode materials for lithiumion batteries(LIBs) and their underlying storage mechanisms were investigated. Instead of a step-bystep reduction of each individual metal cation, the HEFs seem to exhibit a single-step reduction process,indicating a solid solution compound instead of merely a mixture of different metal fluorides. It was also observed that the electrochemical behavior of the HEFs depends on each individual incorporated element. Therefore, by altering the elemental composition, new materials that exhibit improved electrochemical properties can be designed. Remarkably, HEFs with seven incorporated metal elements exhibited a better cycling stability as well as a lower hysteresis compared to binary metal fluorides.These findings offer new guidelines for material design and tailoring towards high performance LIBs.
基金Project supported bythe National Natural Science Foundation of China (20401006)Natural Science Foundation of Henan Province (200510475019)
文摘Organic-dispersible lanthanide fluorides nanocrystals were synthesized at a large scale using colloid-extraction method, in the presence of dialkyl-dithiophosphinic acid (DDPA) as the extraction agent. The products were characterized by means of X-ray powder diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and Fourier transformation infrared (FTIR) spectroscopy. It was found that the synthesized lanthanide fluorides nanoparticles had high purity and crystallinity, and could be well dispersed in organic solvents such as chloroform, toluene etc., which could be closely related to the surface-capping of the nanocrystals by the DDPA molecules. Moreover, the nanocrystals before and after extraction by DDPA showed few differences in the microscopic morphologies. It was implied that DDPA as the extraction agent had good protection to the nanocrystals as well, which could be essential to the commercial application of the titled rare earth nanocrystals as novel multifunctional additives in the fields of lubrication.
基金Funded by the Natural Science Foundation of Shaanxi Province(No.2018JQ2057)Shaanxi Provincial Education Department(No.17JK0151)Ph D Research Foundation Project of Shaanxi University of Technology(No.209020195)
文摘Fluoride nanoparticles with multiform crystal structures and morphologies were successfully synthesized by a facile, effective, and environmentally friendly coprecipitation method. Transmission electron microscopy (TEM) was used to characterize the nanoparticles. The nanoparticles were modified by PEI, CTAB, PAA and Ci, respectively. It was feasible for function by -COOH and -NH2 groups, due to the surface modification. Moreover, different surface modifications of the nanoparticles were examined. The possible formation mechanisms for fluoride nanoparticles with surface modification were presented in detail. More importantly, it is expected to be widely applied to biomedicine.
文摘The thermodynamic and dynamic behaviour of Ni<sup>2+</sup>|Ni couple in FLINAK melt is investigated by us-ing EMF measurement and micropolarization method.The couple shows the Nernstian reversibility and alarge exchange current density(6 mA·cm<sup>-2</sup>).A single crystal LaF<sub>3</sub> which is a fluoride ion conductor usedas a membrane of the Ni<sup>2+</sup>|Ni couple reference electrode is reliable in FLINAK melts at 973 K.The poten-tial of LaF<sub>3</sub> membrane reference electrode is constant within±2 mV.The boron nitride used as a saltbridge was not good in FLINAK melts.The platinum electrode is studied by using micropolarization.Theequilibrium potential of Pt electrode is dependent on the absorption and the electrochemical reaction.Thepotential is stable for a constant composition at constant temperature.
文摘An experimental device is constructed for measuring the density and liquidus temperature of molten fluorides by using the Archimedean and cooling curve methods respectively.Its operation is tested by measuring the density and liquidus temperature of NaCl salt.The accuracy of the liquidus temperature measurement is about±1 K.The density of NaCl measured is in good agreement with the widely recognized data and the deviation is less than 0.2%.The liquidus temperature and density of a typical heat transfer fluoride LiF-NaF-KF(46.5-11.5-42mol%)are investigated.
基金The project supported by the National Natural Science Foundation of China
文摘The lattice sites occupied by samarmm ions in KMgF<sub>3</sub> were ascertained The relationship be-tween valent state of samarium ion in hosts and substituted lattice sites was mvestigated using fluorescentspectra.It is found that the valent state of samarium in different cationic lattice sites is different The internalrelation between the valent state of samarium ion and occupied lattice site was
文摘For developing coating materials, the fluorides of scandium, lanthanum, strontium, barium, magnesium and aluminum were produced from their oxides and chlorides by means of exposure to chlorine trifluoride gas at temperatures between room temperature and 700°C. The metal chlorides could be easily fluorinated even at room temperature, while the metal oxides required temperatures higher than 300?C. After the heating in ambient hydrogen at 1100°C, the fluorides of lanthanum and barium showed very low weight losses at 1100°C, although the weights of the other fluorides significantly decreased. These materials may work as protective films against corrosive and high temperature environments, particularly when using the chlorine trifluoride gas.
基金National Natural Science Foundation of China(No.21971228)for financial support。
文摘A nickel-catalyzed direct hydromonofluoromethylation of unactivated olefins with industrial raw fluoroiodomethane is developed,furnishing various primary alkyl fluorides in a step-economic manner.The key factor to success is the use of pyridine-oxazoline as ligand and(MeO)_(2)MeSiH as the hydrogen source.This transformation demonstrates high efficiency,mild conditions,good functional-group compatibility and great potential in the drug discovery.
基金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(Nos.21977088 and 21672194)the National Natural Science Foundation of China-Shandong Joint Fund(No.U1906213)。
文摘L-Hexoses are key components of many biologically relevant natural products and pharmaceuticals.As rare sugars,L-hexoses are not readily obtained from natural sources.Access to L-hexose building blocks from commercially available and inexpensive D-sugars is highly desirable from the viewpoints of organic synthesis and drug discovery.As demonstrated by the convenient preparation of L-glucosyl,L-galactosyl,and L-mannosyl fluorides from readily availableβ-D-C-glucosyl,β-D-C-mannosyl,andβ-D-C-galactosyl derivatives,we describe a novel and efficient approach to the demanding L-glycosyl fluorides.
基金The authors gratefully acknowledge the financial support from the National Natural Science Foundation of China(grant no.22271151)and the Distinguished Youth Foundation of Jiangsu Province.
文摘A practical one-pot preparation of carbamoyl fluorides from easily obtained pyridine N-oxide,commercially available secondary amines and synthetically versatile difluorocarbene precursors(Ruppert-Prakash reagent or Chen's reagent)was developed herein,which dexterously resorted to the oxidation of difluorocarbene by external pyridine N-oxide to produce the toxic and gaseous fluorophosgene in situ.Notable features of this method include nice functionality tolerance,late-stage modification of drug molecules and the recoveryand recycle of quinoline.
基金the financial support from Liaoning Sci-ence and Technology Development Foundation Guided by Cen-tral Government(No.2021JH6/10500139)the Fundamental Research Funds for the Central Universities(No.N2205003)+2 种基金the financial support from the National Natural Science Foundation of China(No.52003007)Nat-ural Science Foundation of Hebei Province(No.E2019409063)Langfang top-notch talent(No.LFBJ202004).
文摘Potassium ion capacitors(PICs)are regarded as promising large-scale aqueous energy storage systems.However,due to the poor K^(+)transport kinetics and the structural instability of the cathode materials,the key issues of limited energy density and poor cyclic stability are obstacles to the in-depth growth of PICs.Herein,a novel O-doped perovskite fluoride is demonstrated via an in-situ electrochemical oxidation strategy as the cathode for PICs,introducing additional defects that improve the capacitance and facilitate the reaction kinetics of the electrode.During the electrochemical oxidation process,it is discovered that the perovskite fluoride crystal tends to transform into disordered O-doped KMnF 3(K_(x)MnF_(y)O_(z)),realizing a structural reconstruction at the electrode material/electrolyte interface.The First-principles calculations based on density functional theory(DFT)are performed to confirm that the improved electrical conduc-tivity and low ionic adsorption energy may be ascribed to the substitution of oxygen for fluorine.The obtained K_(1.14)MnF_(1.17)O_(1.26) cathode achieves a high specific capacitance of 694 F g^(-1) at 1 A g^(-1),as well as high capacitance retention of 91.3%after 10,000 charge/discharge cycles in mild K_(2)SO_(4) electrolyte.This study provides an effective strategy to improve the capacitive performance of perovskite fluoride cathode materials in electrochemical energy storage.
基金Project supported by the National Natural Science Foundation of China (10774012, 10874014 and 10979009)
文摘The recent results on hydrothermal synthesis of mixed rare earth-alkali or ammonium fluorides were presented. The initial ratios of the starting materials, pH value and reaction temperature were the critical factors for obtaining the single-phase product. Four main types of complex rare earth fluorides, AREF4, A2REF5, ARE2F7 and ARE3F10 (A=Na+, K+, Rb+, NH4+), appeared in the primary hydrothermal reactions. The correlation between cation sizes and the formation of mixed rare earth fluorides under mild hydrothermal condition was given.
基金financially supported by the National Natural Science Foundation of China(Nos.21502240,81972824)Guangdong Basic and Applied Basic Research Foundation(Nos.2020A1515010684,2020A1515011513)Guangdong Provincial Key Laboratory of Chiral Molecule and Drug Discovery(No.2019B030301005)。
文摘Since the sulfur(Ⅵ)fluoride exchange reaction(SuFEx)was introduced by Sharpless and co-workers in 2014,this new-generation click chemistry has emerged as an efficient and reliable tool for creating modular intermolecular connections.Sulfonyl fluorides,one of the most important sulfur(Ⅵ)fluoride species,have attracted enormous attention in diverse fields,ranging from organic synthesis and material science,to chemical biology and drug discovery.This review aims to introduce seminal and recent progresses on the synthetic methods of sulfonyl fluorides,which include aromatic,aliphatic,alkenyl,and alkynyl sulfonyl fluorides.While not meant to be exhaustive,the purpose is to give a timely overview and insight in this field,and stimulate the development of more efficient synthetic methods of sulfonyl fluorides.
基金supported by the National Natural Science Foundation of China(Nos.21790332,22071105,and 22031008)by the QingLan Project of Jiangsu Education Department.
文摘Hydrofluoride is an industry-preferred fluoride source,and finds extensively application to manufacture diverse fluoro chemicals.The Et3N-3HF complex is a liquid HF with improve safety.In this work,we report electrochemical synthesis of a series of sulfonyl fluoride with Et3N-3HF as fluoride source.The sulfinic salt is a smell-less,non-volatile,and air-stable sulfur source in this reaction.With the combination of Et3N-3HF and aryl/alkyl sulfinic salt,the sulfonyl fluorides are achieved without the use of external oxidant.In addition,we demonstrate further advantage in a tandem reaction involving Pd-catalyzed C—S cross-coupling and formation of S—F bond.A variety of functional groups including amino acids,heterocycles,halides are well tolerated.
基金supported by the project of China Geological Survey(Grant No.DD20221677-2)the fundamental research funds of Chinese Academy of Geological Sciences Basal Research Fund(Grant No.JKYQN202307).
文摘Fluoride and nitrate enriched groundwater are potential threats to the safety of the groundwater supply that may cause significant effects on human health and public safety,especially in aggregated population areas and economic hubs.This study focuses on the high F^(−)and NO_(3)^(−)concentration groundwater in Tongzhou District,Beijing,North China.A total of 36 groundwater samples were collected to analyze the hydrochemical characteristics,elucidate genetic mechanisms and evaluate the potential human health risks.The results of the analysis indicate:Firstly,most of the groundwater samples are characterized by Mg-HCO_(3) and Na-HCO_(3) with the pH ranging from 7.19 to 8.28 and TDS with a large variation across the range 471-2337 mg/L.The NO_(3)^(−)concentration in 38.89%groundwater samples and the F^(−)concentration in 66.67%groundwater samples exceed the permissible limited value.Secondly,F^(−)in groundwater originates predominantly from water-rock interactions and the fluorite dissolution,which is also regulated by cation exchange,competitive adsorption of HCO_(3)−and an alkaline environment.Thirdly,the effect of sewage disposal and agricultural activities have a significant effect on high NO3-concentration,while the high F^(−)concentration is less influenced by anthropogenic activity.The alkaline environment favors nitrification,thus being conducive to the production of NO_(3)^(−).Finally,the health risk assessment is evaluated for different population groups.The results indicate that high NO_(3)^(−)and F^(−)concentration in groundwater would have the largest threat to children’s health.The findings of this study could contribute to the provision of a scientific basis for groundwater supply policy formulation relating to public health in Tongzhou District.
文摘The quality upgrading and deashing of inferior coal by chemical method still faces great challenges.The dangers of strong acid,strong alkali,waste water and exhaust gas as well as high cost limit its industrial production.This paper systematically investigates the ash reduction and desilicification of two typical inferior coal utilizing ammonium fluoride roasting method.Under the optimal conditions,for fat coal and gas coal,the deashing rates are 69.02%and 54.13%,and the desilicification rates are 92.64%and 90.27%,respectively.The molar dosage of ammonium fluoride remains consistent for both coals;however,the gas coal,characterized by a lower ash and silica content(less than half that of the fat coal),achieves optimum deashing effect at a reduced time and temperature.The majority of silicon in coal transforms into gaseous ammonium fluorosilicate,subsequently preparing nanoscale amorphous silica with a purity of 99.90%through ammonia precipitation.Most of the fluorine in deashed coal are assigned in inorganic minerals,suggesting the possibility of further fluorine and ash removal via flotation.This research provides a green and facile route to deash inferior coal and produce nano-scale white carbon black simultaneously.
文摘Eu<sup>2+</sup> and Ce<sup>3+</sup> are important rare earth ions with variable valences. There existtwo kind of transition emission, d-f and f-f for Eu<sup>2+</sup>. Eu<sup>2+</sup> is a good candidatefor the activators of UV-visible tunable laser and luminescent materials due to itstransition characteristics. Ce<sup>3+</sup> displays only d-f transition, which is different fromother rare earth ions. Because of the transition properties of Eu<sup>2+</sup> and Ce<sup>3+</sup>, theyare used both as good activators and as efficient sensitizers. Spectral
