Preparation And Electrochemical Application Study On Conductive Metal-Organic Framework (MOF) Materials

Metal organic framework(MOF)is a kind of crystalline porous materials,which is composed of metal ions/clusters and organic ligands via coordination,possessing high specific surface areas,tailable surface chemistry,and structrue diversity et al.Benefiting from the unique structural functionalities,MOF materials have also exhibited great research values in the field of electrochemistry.Especially,a series of MOF materials consisting of pheny/triphenyl organic ligands displays excellent electrical conductivity,which has abundant of potential advantages in electrochemical applications.On these foundations,we systematically and deeply studied the metal element composition and composite construction based on conductive MOF materials via different integration strategies,and further explored their performances of electrocatalysis,electrochemical sensors and supercapacitors.The main contents of this thesis include:(1)We prepared the bimetallic composites of Fe1Cox-HHTP(HHTP=2,3,6,7,10,11-hexahydroxytribenzene)by "one-pot method" strategy.The contents of different metal elements in the composites can be tuned via altering the introduced ratio of Fe and Co,thus improving the electrochemical active surface and charge transfer ability,which contributes to optimize the oxygen evolution reaction(OER)performance.Further investigations showed that the composites were gradually transformed into oxyhydroxides upon the OER process.(2)We prepared a series of single,binary and ternary M-Catecholate(M-CAT)materials through solvothermal synthesis and cation exchange method.These two preparation strategies can not only adjust the molar ratio of metal elements in CAT materials but also greatly increase the Fe content in the composites,and thus enhancing the OER electrocatalytic acitivity.Based on the work in Chapter 2,M-CAT materials can be considered as a type of OER "precatalysts",which could be converted to the highly active oxyhydroxides under electrochemical conditions.Among them,FeCo0.6Ni0.4-CAT shows a lower overpotential(277 mV)and an excellent electrochemical durability.(3)We prepared the GO/YbHHTP composites via in-situ growth of YbHHTP MOFs on the graphene oxide(GO)surface using hydrothermal synthesis.This preparation strategy allows the YbHHTP nanorods homogeneously distributing on the GO surface,which not only realizes the electronic interactions between GO and MOF but also inherits the well conductivity of YbHHTP and the high diffusion ability of GO to detected molecules.As the electrochemical sensors,GO/YbHHTP modified electrodes show high sensitivity,well anti-intererence,great reproducibility,excellent stability and huge potential in practical applications.(4)We prepared the CFP/HoHHTP by in-situ growth of HoHHTP nanowires on the carbon fiber paper(CFP)using hydrothermal synthesis method.The controllable growth of HoHHTP nanowires on CFP was realized via optimizing the ratio and concentration of metal ions and organic ligands,the concentration of initiator,reaction temperature and time.The charge storage mechanism of CFP/HoHHTP was verified to be electric double layer capacitance and surface pseudocapacitance by electrochemical test.Additionally,we also systematically evaluated the capacitance of CPF/HoHHTP.