| With the increasing demand for new energy in modern society,fossil energy resources are increasingly scarce,and the environmental problems caused by its combustion are becoming increasingly severe.Therefore,the development of renewable energy and continuous storage energy technology has become the main way to resolve the risks of resources and environment in the global scope.As an energy storage device with high power density,environmental friendliness and long cycle life,supercapacitor has been listed as a research and development hotspot in the field of green chemistry.Electrode materials are the core components of supercapacitors,so it is essential to design and synthesize high-performance electrode materials.Keggin polyacid cluster contains 12 coordination atoms,which is considered as an"electron pool" or "electronic sponge".Keggin polyacid cluster has the ability of reversible multi-electron redox,and can quickly receive or transmit electrons without changing the main structure.Keggin polyacid cluster is a new type of pseudo-capacitor electrode material with electrochemical storage capability.However,unmodified POMs has the disadvantages of weak conductivity and small specific surface area,and it is easy to dissolve in polar solvents,so it is difficult to exert its excellent redox characteristics.In this paper,different kinds of Cu/Ag complex units were introduced into Keggin{AsW12/Mo12} system by in-situ synthesis,and 4 cases of Cu/Ag-phen ligand modified arsentungstates and 3 cases of tetravanadium substituted arsenmolybdates modified by copper caps were constructed.The electrocatalytic properties,supercapacitor properties and sensing properties of some compounds of Keggin derivatives with different degrees of modification were studied,and the relationship between structure and properties of compounds was summarized.The main results are as follows:Using elemental composition analysis,IR,TG,XRD,single crystal X-ray diffraction technique and valence bond calculation,the molecular formulas of compounds 1-7 were determined as follows:(Cu?(H2O)0.5phen)2[{Cu?(phen)2}2{AsW?5W?7O40}]·2H2O(1),(Cu?(phen)2)[{Cu?(phen)}2{Cu?2AsW?2W?10O40}]·3H2O(2),(Cu?(phen)2)4(Cu?5(phen)4Cl4)[AsW?2W?10O40]·3H2O(3),(Ag(phen)2)3(Ag(phen)3)[AsW?W?11O40](4),(Hbiim){Cu?(biim)3)}2[{Cu?2AsMo?8V4O40}]·3H2O(5),{Cu?(bipy)2}[{Cu?(bipy)2}2{Cu?2AsMo?8V4O40}]2·5H2O(6)[{Cu?2(Hdpp)2(pz)(H2O)2}{Cu?2AsMo?7Mo?V4O40}]·H2O(7),(phen=1,10-phenanthroline,bipy=2,2-bipy,biim=Bisimidazole,dpp=pyraz ino[2,3-f][1,10]-phenanthroline)Further analysis of crystal structure shows that compound 1 is a three-dimensional supramolecular {AsW12} organic-inorganic hybrid modified by "wing" type double-supported {Cu(phen)2} metal complex with ?-? stacking effect;Compound 2 is a "hat" double-supported zero-dimensional {AsW12} organic-inorganic hybrid modified by four {Cu(phen)} structural units;Compound 3 is a three-dimensional supramolecular{AsW12} organic-inorganic hybrid that is co-modified by a central symmetric pentanuclear complex {Cu5(phen)4Cl4} and a mononuclear complex {Cu(phen)2}.Compound 4 is a three-dimensional supramolecular {AsW12} organic-inorganic hybrid modified by different kinds of Ag-phen complex units;Compound 5 is double copper cap tetravanadium substituted arsenic molybdenum vanadium polyoxometalate modified by {Cu(biim)3} complex fragment;Compound 6 is a {cuiii(bipy)2} complex modified double copper cap tetravanadium substituted arsenic molybdenum vanadate 3-D supramolecular compound;Compound 7 is a one-dimensional chain structure of double copper cap tetravanadium substituted arsenmolybdate modified by dinuclear{Cu?2(Hdpp)2(pz)} units.Compounds 1-7 realized the functional modification of Keggin polyacid by polynuclear metal-organic complexes under the combined action of d10 metal and rigid ligand respectively.The synthesized compounds 1-7 were prepared into glassy carbon electrode and carbon fiber cloth electrode,and the performances of supercapacitors were tested by cyclic voltammetry experiment,constant current charge-discharge experiment,cyclic stability and AC impedance experiment,respectively.The results show that compound 1 in {ASW12} series has the best super-electric performance,which can be attributed to the regular pore structure in its structure,expanding the electron transmission channel and promoting the electron transfer.In vanadium substituted arsenic molybdenum series,compound 7 has the best super-electric performance(when the current density is equal to 2,4 A g-1,its specific capacitance is 1020 F g-1.After 3000 cycles,the capacitance retention rate exceeds 90%),which is because the modification of binuclear complexes enriches redox centers.In addition,the super-electric performance of tetravanadium substituted arsenmolybdate is generally better than that of {AsW12} series,which may be due to the stronger redox ability of vanadium and tungsten than that of tungsten.Compounds 1-7 can catalyze the oxidation of AA and the reduction of H2O2.Comparing the catalytic effects,the results are consistent with the super-electric performance.Compounds 1 and 7 with better catalytic effects in two kinds of polyacids are selected to test their sensing performance.The results show that both compounds have good sensing response to AA and H2O2,and have good anti-interference ability,stability and reproducibility. |
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