Application Of Electrochemical Deposition Of Manganese Dioxide On Modified Carbon Materials In Supercapacitors And Water Treatment

With the continuous development of society,the problems of energy shortage and environmental pollution are becoming increasingly conspicuous.It is urgent to develop efficient,pollution-free and abundant renewable energy and accelerate the construction of a new environmental governance system,which is also a necessary strategic goal for the long-term sustainable development of human society.As a clean,efficient,and easy to operate and control method,the electrochemical method is widely used in the field of energy storage and water treatment.In this field,electrode materials are essential core components for both electrochemical energy storage and electrochemical water treatment technology,so it is particularly important to research and develop electrode materials with high efficiency and good stability.This work selected carbon materials as the initial materials and modified the selected carbon materials by different methods to improve hydrophilicity,enhance electrochemical activity and increase specific surface area of them.Subsequently,the application of electrochemical deposition of manganese dioxide on modified carbon materials in supercapacitors and water treatment was studied.The following sections detail the main findings and outcomes of this work:(1)Removal of manganese ions from wastewater by modified graphite paper and the study on electrochemical properties of its composites with manganese dioxideModified graphite paper(MGP)with rich active sites treated by the anion intercalation method was used as a working electrode for the electrochemical removal of manganese ions(Mn2+)in manganese-containing water,and the effects of different factors on Mn2+ removal were explored first.Then,the electrochemical performance of the deposited MGP/MnO2 composite was tested as the supercapacitor electrode.The experimental results show that it not only achieves the goal of removing excess Mn2+ in water efficiently but also has good electrochemical performance.(2)Preparation and electrochemical properties study of modified graphite felt/manganese dioxide compositesModified graphite felt(MGF)with good hydrophilicity and rich active sites was prepared by electrochemical/chemical composite modification,and the MGF/MnO2 composite electrode was fabricated by the electrochemical deposition of MnO2 on the MGF.The OH-H-H2O2GF/MnO2 composite obtained under the optimum parameters shows a specific capacitance of 225.2 F/g at the current density of 0.5 A/g,which is 282%of the original GF/MnO2 composite.After repeated,continuous charging and discharging cycles with different current densities,the specific capacitance retention rate is 86.9%,showing a good cycle rate performance.(3)Preparation and electrochemical properties study of high temperature chemical etching porous graphite felt/manganese dioxide compositesPorous graphite felt(PGF)with a high specific surface area was fabricated by high temperature chemical etching,and the effects of different temperatures and treatment time on the surface morphology and specific surface area of porous materials were investigated.The experimental results show that PGF(700-4)calcined at 700℃ for 4 h has a high specific surface area of 29.279 m2/g,which is 9.3 times of the original GF.PGF(700-4)/MnO2 prepared by using PGF(700-4)as substrate material has excellent electrochemical performance,and it has a high specific capacitance of 402.8 F/g at a current density of 0.5 A/g.The cycle rate performance test shows that its specific capacitance retention rate can reach 89.0%when it returns to the initial current density after multiple charges and discharges under different current densities.After 5000 charge-discharge cycles at a current density of 2 A/g,its specific capacitance is 102%of the initial specific capacitance,showing excellent cycle stability and great application potential.