Electrochemical Synthesis Of ZIF-8 Materials And Capacitive Properties

In recent years,metal-organic framework materials?MOFs?have become a hotspot of materials due to their many characteristics such as multi-porosity,high specific surface area,and functional structure.Among them,bimetallic MOFs have given traditional MOFs materials unique and rich properties due to the introduction of new metal ions,which is the future development trend of MOFs materials.At present,the traditional synthesis methods of bimetallic MOFs have the disadvantages of complicated operation and high energy consumption.However,the electrochemical method can quickly synthesize products under normal temperature and pressure,which has the advantages of clean and efficient,so it has become our preferred synthesis method.In this paper,ZIF-8 was first synthesized by electrochemical method,and then metal ion Co²⁺was introduced to modify it to synthesize bimetallic Zn/Co-ZIF-8.By changing the reaction solvent ratio,the voltage and The reaction time and the amount of metal cobalt salt were added to explore the optimal synthesis conditions of the two materials,and the capacitance properties of the two materials were tested and compared under the optimal conditions.Put forward the method of regulating ZIF-8 material.The main content of the paper is as follows:According to XRD,SEM,FTIR,nitrogen adsorption,EDS and other characterization results,the ZIF-8 synthesized under the conditions of a volume ratio of DMF to ethanol of 1:4,an applied voltage of 5 V,and a reaction time of 2 h was crystalline.The octahedral structure with high degree and good morphology has a BET specific surface area of 1235.48 m²/g.Under the condition that the volume ratio of DMF to ethanol is 1:4,the applied voltage is 5 V,the reaction time is 2 h,and the addition amount of cobalt salt is 0.08 g,the crystallinity is better,and the layered cubic structure of Zn is uniform Zn/Co-ZIF-8 material with a specific surface area of 1114.05 m²/g.EDS detected that the sample contained two metal elements,zinc and cobalt,and confirmed that the two metal ions successfully participated in the coordination.The above materials are used as electrode active preparation electrodes,and its capacitance performance is explored through cyclic voltammetry?CV?,constant current charge and discharge?GCD?,and alternating current impedance?EIS?.The results show that there are a pair of redox peaks in the CV curve of the ZIF-8electrode material at different scanning speeds,which show obvious pseudo-capacitance characteristics.At a current density of 1 A/g,the specific capacitance of the ZIF-8 electrode material is 77 F/g.When the current density is changed,the rate performance is average.After 2000 cycles,the specific capacitance can maintain 88%of the initial value.The CV curves of the Zn/Co-ZIF-8 electrode material at different scanning speeds also have a pair of redox peaks.At a current density of 1 A/g,the specific capacitance of the Zn/Co-ZIF-8 electrode material reaches 189 F/g.When the current density is changed,the rate characteristics are good.After 2000 cycles,the specific capacitance value can still maintain 90.5%of the initial value.After EIS test,the electrode resistance of Zn/Co-ZIF-8 material is lower than that of ZIF-8 material.The results show that the introduction of additional metals effectively improves the performance of the material.After carbonization,C-Zn/Co-ZIF-8 material has significantly improved capacitance performance compared to before carbonization.The constant current charge and discharge test shows that the C-Zn/Co-ZIF-8 material has a capacitance of 243 F/g when the current density is 1 A/g,and has higher conductivity.