The Synthesis And Properties Of Based On Co,Mn,Ni Chalcogenide Nanomaterials

As the transition metal materials have unique physical and chemical properties,they are widely used in catalysis,energy storage,electromagnetic,sensing and other fields.Among them,the transition metal chalcogenide nanomaterials?based on Co,Mn,Ni?have the advantages of simple preparation method,easy control of the morphology and high electrochemical activity,which has aroused the concern of the researchers.For the current comparison of the forefront of the supercapacitor energy storage materials,the preparation of simple methods and material performance has always been a consistent pursuit of the researchers.In this paper,the transition metal chalcogenide nanomaterials?based on Co,Mn,Ni?with unique nanostructures have been preapared by means of hydrothermal,ion exchange and material compounding.Owing to the prominent electrical conductivity,high electrochemical activity and large specific surface area,they have excellent electrochemical energy storage performance.The main contents of this paper are as follows:1.The precursor?Co?OH?₂?of the ultra-thin porous Co₃O₄ was synthesized by low-temperature hydrothermal method and nickel foam as the template.And the precursor Co?OH?2 was annealed at high temperature to obtain ultra-thin mesoporous Co₃O₄ nanosheets.After the TME and BET characterization,the Co₃O₄ nanosheets consisted of a large number of mesopores,the pore size was about 2-12 nm,and the specific surface area was 2.24 times larger than the precursor.The prepared Co₃O₄ nanosheets were used as supercapacitor electrode materials,and the capacitance was 610 F g-1 when the current density was 1 A g-1 in 2 M NaOH electrolyte.The cycles test at a current of 4 A g-1,the specific capacitance can still be maintained at 94.5% after 3000 cycles.It is applied in an asymmetric electrode,which exhibits excellent performance.The above-mentioned ultra-thin porous Co₃O₄ nanosheets are a good energy storage electrode material.2.After the ultra-thin porous Co₃O₄ nanosheets have been obtained,the O atoms are replaced by S atoms by simple ion-exchange conditions under hydrothermal conditions.Due to the load of Co₃O₄ nickel foam is partially reactive,so the product contained in the part of the NiS.In the 2 M KOH electrolyte,the specific capacitance of the transition metal sulfide Co3S4/NiS is 12 times larger than the pristine ultra-thin porous Co₃O₄ at the same current density.In the asymmetric electrode test,the specific capacitance of the transition metal sulfide Co3S4/Ni S is 1810 mF cm-2 at 4 mA cm-2,and its potential window can reach 1.6 V and deliver a high energy density of 6.44 Wh m-2 at a high power density of 32 W m-2.Moreover,we applied this device to successfully light five light-emitting-diodes for 8 minutes in a simulated solar illumination system.3.The transition metal oxide compounds Mn O2@NiMoO4 was synthesized by two-step hydrothermal method,and it as a flexible supercapacitor energy storage performance was studied.The MnO2 nanowires were used as templates,and then NiMo O4 nanosheets were grown on MnO2 nanowires by hydrothermal method.Through the structural characterization and found that the transition metal oxide compounds is a heterogeneous structure with MnO2 nanowires as nuclei.With this heterostructure transition metal oxide as a positive electrode,porous carbon as a negative electrode to manufacture flexible asymmetric supercapacitor,exhibiting a high capacitance of 186.8 F g-1 at a scan rate of 10 mV s-1,super-long cycling life with a 132.7% retention rate after 20000 cycles,and super flexibility with no obvious changes of specific capacitance after bending to 30 to 150o?the corresponding radius of curvature is 4.5 mm to as small as 1.0 mm?.Such superior electrochemical performance shows MnO2@NiMoO4 is a potential supercapacitor electrode material.