Adsorption And Supercapacitor Properties Of Novel Metal-Organic Frameworks And Derivatives

Metal–organic frameworks?MOFs?,as porous crystalline materials,have the characteristics of ordered crystalline structure,tunable pore size,large specific surface area and various functional groups.The multi-functional MOFs can not only realize the adsorption and separation of materials,but also as promising electrodes for supercapacitors,which has become a hot spot of research.This work focuses on the design and synthesis a novel MOF material based on H4AOBTC ligand,and then studies its adsorption properties in detail.Moreover,we have prepared nanocrystalline MOFs and its derivatives by morphological control,and then research their supercapacitor capacitance,as follows:A novel Zn-based metal-organic framework,named as[Zn?phenDIB??AOBTC?_0.5]?1?was synthesized from the mixed ligands,3,3?,5,5?-azoxybenzenetetracarboxylic acid?H₄AOBTC?and1,4-bis?1H-benzo[d]imidazol-1-yl?benzene?phenDIB?ligand.This MOF displays extraordinary thermostability in boiling water for 12 h and chemical stability in a wide pH range of 2-13.The most intriguing feature is that it can successfully separate cationic dyes from mixed dye molecules in aqueous solution with high effectivity and selectivity,even for rhodamine B molecule with a large size.Furthermore,this material is reusable,and the adsorbed dye molecules can be released and recovered completely.It is very important for the practical application from a view of environmental protection and resource recycling.Cu-Asp polymer nanowires and Ni-BDC MOF nanospheres were prepared by room temperature diffusion and solvothermal method,using L-aspartic acid and terephthalic acid as ligands,respectively.Then they were sacrificed as templates to transform into corresponding porous metal oxides by controlling appropriate temperature conditions.The electrochemical performance of PCP/MOF and its derivatives were tested by three electrode systerm in KOH solution.Electrochemical researches indicate that Cu-Asp nanowires possess high specific capacitance of 367 F g^-1 under the current density of 0.6 A g^-1,and excellent cycling stability?94%retention over 1000 continuous cycles?.After calcining,CuO nanotubes exhibit high rate capacity up to 77%,and long-term stability of 96%.In addition,NiO nanospheres calcined at 400??N400?exhibit the best charge storage with a specific capacitance of 473 F g^-1 at the current density of 0.5 A g^-1 and with 94%capacitance retention even after 3000 cycling tests.For this merit,the N400//active carbon?AC?asymmetric supercapacitor?ASC?was assembled to examine the practical application of the N400 sample,which presents high energy density of 21.4 Wh kg^-1at power density of 375.8 W kg^-1.Particularly,the N400//AC ASC exhibits outstanding cycling stability,and its capacitance retention can still reach up to 92.3%after 3000 cycles.These results fully demonstrate that the strategy of synthesizing porous nanowires,nanotubes and nanospheres can be used to produce electrode materials for more efficient energy storage.From the discussion above,this paper is devoted to design and synthesize novel MOFs,then the prepared MOFs and their derivatives were systematically analyzed and characterized,and their applications in adsorption/separation and supercapacitors were also investigated.Furthermore,MOF-derived metal oxides have novel morphology and porosity,which provide a wider application prospect for the development of MOFs materials.