Controllable Synthesis And Application In Supercapacitors Of Micro/nano Bimetal NiCo-MOF And Their Derivativesmaterials

As a new type of electrochemical energy storage devices,SCs have attracted wide attention on account of their advantages of fast charging and discharging performance and long cycle life.Improving the electrochemical properties of the electrode material is the key to improve the overall performance of the supercapacitor devices.Recently,the application of nanostructured materials to the electrodes of SCs has been widely reported,which has become a hotspot in this field.Nanomaterials can not only provide large surface areas for energy storage,but also shorten ion diffusion pathways.Metal-organic frameworks(MOFs)with high surface area and adjustable chemical structure has attracted great attention as an advanced material for electrochemical transformation.In this paper,NiCo-MOF,NiCo-MOF derived sulfides(NiCo-S/NiCo-MOFs)and NiCo-MOF derived carbon composite(NiCo/C)were prepared by solvent heating and calcination.And the properties of supercapacitors of this serie of materials were studied.It includes the following three parts:(1)Ni/Co bimetallic organic framework nanosheet assemblies were synthesized by a typical one-pot synthesis procedure at 155? via adjusting the proportion of metal sources.These as-prepared MOFs materials were directly employed as SCs electrode,and the results showed that NiCo-MOF-1 synthesized from Ni/Co at a ratio of 2:1 showed better electrochemical properties.When at a current density of 0.5 A g-1,NiCo-MOF-1 electrode can deliver a high discharge capacity of 100.18 mAh g-1,and obtains a capacity retention of 81.00%over 3000 cycles.Meanwhile,the discharge capacity of NiCo-MOF-1//AC is 85.75 mA h g-1 These results demonstrate that the synthic of bimetallic or polymetallic organic frameworks with different morphologies by controlling the ratio of doped metals is a scheme for exploring more excellent electrochemical properties of MOFs.(2)By a facile solvothermal reaction,NiCo-MOF micro/nanometer sheets were obtained via employing Co(NO3)2·6H2O,Ni(NO3)2·6H2O,PTA and mixed solvent as raw material.NiCo-S/NiCo-MOFs composite material was successfully prepared by a solvothermal reaction,with thioacetamide(TAA)as sulfur source.As the SCs electrode materials,the S1(TAA:MOF=1:1)show better energy storage performance than S2(TAA:MOF=1:2).In the three-electrode system,the discharge capacity of the S1 can reach 118.44 mAh g-1,and discharge capacity of the S1//AC is 80.89 mA h g-1.(3)By a facile solvothermal reaction,NiCo-MOF micro/nanometer ball were obtained with employing Co(NO3)2·6H2O,Ni(NO3)2·6H2O,BTC and mixed solvent as raw material.Subsequently,by calcining as-prepared MOF in N2 atmosphere at different temperatures,the NiCo/C composite materials were manufactured.When applied in SCs,the C2(calcined at 550?)electrode exhibits better electrocatalytic performanc than other samples(calcined at other temperatures).In the three-electrode system,the discharge capacity of the C2 can reach 124.72 mAh g-1,and discharge capacity of the C2//AC is 100.13 mA h g-1.