Synthesis-controlled Of Polyoxometalate-based Copper Organic Framework Crystal Materials And Their Research Of Supercapacitor Performance

As a kind of energy storage device with both high power density and high energy density,supercapacitor has been widely used in many fields such as new energy vehicles and portable electronic devices.The electrode materials play an important role of supercapacitor,which directly determine the energy storage effect of the device.RuO₂ electrode material has been paid much attention in the field of supercapacitor because of its excellent energy storage effect,but the high cost limits its wide use.Therefore,the design and preparation of electrode materials with low cost and excellent performance is the key problem to be solved urgently in the field of supercapacitor.Polyoxometalate?POM?-based metal-organic framework?POMOF?crystal material is an ideal new type of supercapacitor electrode material,which has the advantages of both POM and metal-organic framework?MOF?material.Moreover,POMOF has the characteristics of low cost and fast reversible multi-electron transfer ability of RuO₂-like,so it is expected to be a substitute for RuO₂.However,the research work on POMOF crystal materials as electrode materials for supercapacitors is still few reported,and this field is still in its infancy.Based on this,the idea that crystal materials can be clipped and recombined in hydrothermal synthesis process is used in this thesis.By crystal engineering method,Keggin metatungstate acid,silicotungstate acid,phosphotungstate acid and phosphomolybdate acid with similar structure and increasing oxidation performance are selected as POM construction units to react to copper cation with rich coordination mode and btx?1,4-bis?triazacylidene?benzene?with more nitrogen content.Twelve kinds of POM-based copper organic frame crystal materials with novel structure are designed and prepared.The crystal materials are characterized by single crystal X-ray diffraction,powder X-ray diffraction?PXRD?,fourier transform infrared spectrometer?FTIR?,elemental analysis?EA?and so on.The supercapacitor properties of POM-based copper frame materials are studied by cyclic voltammetry?CV?,galvanostatic charge/discharge?GCD?and electrochemical impedance spectroscopy?EIS?,and the relationship between the microstructure and the supercapacitor properties is investigated,and the microstructure which is beneficial to improve the supercapacitor properties of POM based electrode materials is explored.This thesis provides a theoretical and practical basis for the development of POM-ased electrode materials with excellent superelectric properties.The main contents of the study are as follows:1.The metatungstate,which can be reduced by up to 33 electrons,is selected as the POM source,copper acetate as the metal source and btx as the organic ligand source.Three unreported metatungstate-based copper organic framework crystal materials have been designed and synthesized by controlling the same reaction temperature and pH value and regulating the concentration of triethylamine?TEA?in system:[{Cu₆^II?btx?₇?H₂O?₁₂}H₄(W₁₂O₄₀)₂]·12H₂O?1?[{Cu₇^II?btx?₈?H₂O?₁₀}H₂(W₁₂O₄₀)₂]·2H₂O?2?[{Cu₁₀^IICu₂^I?btx?₁₁?H₂O?₁₆}H₂(W₁₂O₄₀)₃]·6H₂O?3?Metatungstate-based copper frame materials of 1³ present 3D self-insertion frame structure,2D finger-tight stacking bilayer structure and 1D+3D pseudo-rotaxane structure.The specific capacitance of materials 1³ electrode is 50.0,19.1 and 31.1 F g^-1 at 3 A g^-1,respectively.2.Silicotungstate is used as POM source,copper acetate as metal source,btx as organic ligand source.Three unreported silicotungstate-based copper organic framework crystal materials have been designed and synthesized through the same reaction temperature and pH value except different concentration of TEA in the system:[Cu^II?btx?₂]₂[SiW₁₂O₄₀]?4?[Cu^I?btx?]₄[SiW₁₂O₄₀]?5?[Cu₄^I?btx?₃][SiW₁₂O₄₀]·2H₂O?6?The silicotungstate-based copper frame materials of 4⁶ present 3D simple host-guest structure,2D layer structure of mixed free metal organic chain and 2D intercalated compact accumulation layer structure.The specific capacitance of materials 4⁶ electrode is 79.8,110.3 and 62.8 F g^-1 at 3 A g^-1,respectively.3.Phosphotungstate is used as POM source,copper acetate as metal source and btx as organic ligand source.At the same reaction temperature,three unreported phosphotungstate-based copper organic framework crystal materials have been synthesizedbychangingthePOMasitsderivative K₅H₂[{Ti?OH??ox?}₂??-O?](?-PW₁₁O₃₉)]·13H₂O,cuprous chloride replacing copper acetate,and pH value,repectively:[Cu₄^IH₂?btx?₅(PW₁₂O₄₀)₂]·2H₂O?7?[Cu^IICu₃^I?H₂O?₂?btx?₅(PW₁₀^VIW₂^VO₄₀)]·2H₂O?8?[Cu₆^I?btx?₆(PW₉^VIW₃^VO₄₀)]·2H₂O?9?Phosphotungstate-based frame materials of 7⁹ present two-dimensional layer structure of mixed free ligand,1D+3D pseudo-rotaxane structure and 3D complex stacking structure.The specific capacitance of materials 7⁹ electrode is 84.8,76.3and 70.3 F g^-1 at 3 A g^-1,respectively.4.Phosphomolybdate is used as POM source,copper acetate as metal source,btx as organic ligand source.At the same reaction temperature and pH value,three unreported phosphomolybdate-based copper organic framework crystal materials have been synthesized by cuprous chloride replacing copper acetate and adding TEA,respectively:[Cu₄^IH₂?btx?₅(PMo₁₂O₄₀)₂]·2H₂O?10?[Cu^IH₂?btx?(PMo₁₂O₄₀)][N?CH₂CH₃?₃]₂·2H₂O?11?[Cu₂^II?btx?₄(PMo₉^VIMo₃^VO₃₉)]?12?The phosphomolybdate-based frame material 10¹2 presents the 2D layer structure of mixed free ligand,the 2D layer structure of mixed free TEA molecule and the 3D nanotube structure.The specific capacitance of materials 10¹2 electrode is 230.5,249.0 and 153.0 F g^-1 at 3 A g^-1,respectively.