A novel and unique nickel-cobalt hydroxyfluorides(NiCo-HF)nanowires material is fabricated by one-pot solvothermal synthesis method for asymmetric supercapacitor.The synthesis mechanism and factors that influence the ...A novel and unique nickel-cobalt hydroxyfluorides(NiCo-HF)nanowires material is fabricated by one-pot solvothermal synthesis method for asymmetric supercapacitor.The synthesis mechanism and factors that influence the formation of the Ni Co-HF nanowires have been further discussed.The as-prepared NiCo-HF electrode exhibits a high specific capacitance of 3,372.6 F g^(à1),and the capacitance retention of 94.3%can be achieved at a high current density of 20 A g^(à1)after 10,000 cycles.The outstanding electrochemical performance of the electrode can be attributed to the synergistic effect of the nanowires morphology and complicated redox process of active material.Furthermore,an asymmetric supercapacitor assembled with Ni Co-HF nanowires as positive electrode and activated carbon as the negative electrode shows an ultrahigh energy density of 83.6 Wh kg^(à1)at a power density of 379.4 W kg^(à1)and an excellent cycling stability with 86.3%capacitance retention after 10,000 cycles,indicating that this novel material has great promise for potential application in energy storage device.展开更多
High-purity AlF3 was prepared by the combined process of leaching the raw material of waste aluminum electrolytes with aluminum chloride,electrolyzing the leaching solution,and then mixing with ammonium hydrogen fluor...High-purity AlF3 was prepared by the combined process of leaching the raw material of waste aluminum electrolytes with aluminum chloride,electrolyzing the leaching solution,and then mixing with ammonium hydrogen fluoride for roasting.Under the optimal leaching conditions of a fluorine to aluminum molar ratio of 2.0,a liquid-to-solid ratio of 12,a temperature of 90℃,and time of 4 h,the fluorine leaching rate can reach 99.15%.Under the action of electrolysis,the H+is reduced to H2 in the cathode,while the remaining OH−combines with AlF^(2+)and AlF^(2+)to precipitate aluminium hydroxyfluoride hydrate.The results show that electrolysis is beneficial to reduce the impurity content of aluminium hydroxyfluoride hydrate.When the current density is 0.2 A/cm^(2),the temperature is 90℃,the stirring speed is 200 r/min,and the electrolysis endpoint pH is 3.0,the total content of Na,K and Ca impurities in the precipitation is only 0.64 wt.%.Moreover,the hydrolysis can be inhibited effectively by adding ammonium hydrogen fluoride in the mixed-roasting process.When the mass ratio of aluminium hydroxyfluoride hydrate to ammonium hydrogen fluoride is 2꞉1,the purity of the AlF3 product is even 99.51 wt.%.Conducively,the high-purity AlF_(3)can be returned to the aluminum electrolysis industry or used as a reagent.展开更多
Semiconductors have been widely used in many high-tech fields such as photo-and electro-catalysis,ion bat-teries,and solar cells.In addition to the earliest discovered elemental and compound semiconductors,such as mon...Semiconductors have been widely used in many high-tech fields such as photo-and electro-catalysis,ion bat-teries,and solar cells.In addition to the earliest discovered elemental and compound semiconductors,such as monocrystalline silicon and metal oxides,new types of compound semiconductors have been discovered.Among them,metal hydroxyfluorides(MOHF)are an emerging type of semiconductor that are easy to synthesize and inexpensive.However,many of their properties and applications are not well understood.Nevertheless,some MOHF materials,such as ZnOHF and CoOHF,have been sufficiently developed,and their applications have been extensively explored.This review focuses on a new compound semiconductor,MOHF,with ZnOHF and CoOHF as the typical.After a short introduction to their physical and chemical properties,their common applications are illustrated with several examples.Subsequently,other less-researched MOHF and MOHF-like materials,as well as their applications,are discussed.Moreover,the expectations and development directions of MOHFs are briefly summarized.展开更多
基金supported by the National Natural Science Foundation of China(51772072,51402081,and 51502071)Natural Science Foundation of Anhui Province(1708085ME100,1508085ME97,and 1608085QE105)+1 种基金the Fundamental Research Funds for the Central Universities(JZ2017HGTB0203,JZ2016HGTB0719,and 201610359018)the financial support from the China Scholarship Council during his visit to Prof. Pulickel M Ajayan’s group at Rice University
文摘A novel and unique nickel-cobalt hydroxyfluorides(NiCo-HF)nanowires material is fabricated by one-pot solvothermal synthesis method for asymmetric supercapacitor.The synthesis mechanism and factors that influence the formation of the Ni Co-HF nanowires have been further discussed.The as-prepared NiCo-HF electrode exhibits a high specific capacitance of 3,372.6 F g^(à1),and the capacitance retention of 94.3%can be achieved at a high current density of 20 A g^(à1)after 10,000 cycles.The outstanding electrochemical performance of the electrode can be attributed to the synergistic effect of the nanowires morphology and complicated redox process of active material.Furthermore,an asymmetric supercapacitor assembled with Ni Co-HF nanowires as positive electrode and activated carbon as the negative electrode shows an ultrahigh energy density of 83.6 Wh kg^(à1)at a power density of 379.4 W kg^(à1)and an excellent cycling stability with 86.3%capacitance retention after 10,000 cycles,indicating that this novel material has great promise for potential application in energy storage device.
文摘High-purity AlF3 was prepared by the combined process of leaching the raw material of waste aluminum electrolytes with aluminum chloride,electrolyzing the leaching solution,and then mixing with ammonium hydrogen fluoride for roasting.Under the optimal leaching conditions of a fluorine to aluminum molar ratio of 2.0,a liquid-to-solid ratio of 12,a temperature of 90℃,and time of 4 h,the fluorine leaching rate can reach 99.15%.Under the action of electrolysis,the H+is reduced to H2 in the cathode,while the remaining OH−combines with AlF^(2+)and AlF^(2+)to precipitate aluminium hydroxyfluoride hydrate.The results show that electrolysis is beneficial to reduce the impurity content of aluminium hydroxyfluoride hydrate.When the current density is 0.2 A/cm^(2),the temperature is 90℃,the stirring speed is 200 r/min,and the electrolysis endpoint pH is 3.0,the total content of Na,K and Ca impurities in the precipitation is only 0.64 wt.%.Moreover,the hydrolysis can be inhibited effectively by adding ammonium hydrogen fluoride in the mixed-roasting process.When the mass ratio of aluminium hydroxyfluoride hydrate to ammonium hydrogen fluoride is 2꞉1,the purity of the AlF3 product is even 99.51 wt.%.Conducively,the high-purity AlF_(3)can be returned to the aluminum electrolysis industry or used as a reagent.
基金supported by the Natural Science Foundation of Shandong Province(ZR2022MF311)Project of Innovation Team in Jinan City for Universities and Institutes(2021GXRC063)+1 种基金Natural Science and Development Foundation of Shenzhen(JCYJ20190807093205660)Young Scholars Program of Shandong University(2018WLJH25).
文摘Semiconductors have been widely used in many high-tech fields such as photo-and electro-catalysis,ion bat-teries,and solar cells.In addition to the earliest discovered elemental and compound semiconductors,such as monocrystalline silicon and metal oxides,new types of compound semiconductors have been discovered.Among them,metal hydroxyfluorides(MOHF)are an emerging type of semiconductor that are easy to synthesize and inexpensive.However,many of their properties and applications are not well understood.Nevertheless,some MOHF materials,such as ZnOHF and CoOHF,have been sufficiently developed,and their applications have been extensively explored.This review focuses on a new compound semiconductor,MOHF,with ZnOHF and CoOHF as the typical.After a short introduction to their physical and chemical properties,their common applications are illustrated with several examples.Subsequently,other less-researched MOHF and MOHF-like materials,as well as their applications,are discussed.Moreover,the expectations and development directions of MOHFs are briefly summarized.
