Research On The Preparation And Application Of Graphene-based Materials

The international demand for energy is increasing rapidly due to the decrease of energy caused by traditional fossil fuels and the aggravation of environmental pollution.Solving pollution problems by implementing cutting-edge technology research on environmentally friendly energy has become a topic of great concern.The need to design efficient and environmentally friendly batteries and fuel cells has become a hot topic in research.As a typical electrochemical energy storage device,the battery has been widely used in daily work.It is the main power source for mobile phones,notebook computers,digital cameras and other equipment,and has a higher energy storage capacity than traditional rechargeable batteries.As an electrochemical transfer device,fuel cell has been used as the energy source of automobile because of its advantages of green,clean,pollution-free and high conversion efficiency.As a typical graphite carbon,graphene has made rapid progress in its potential applications in the fields of catalysis and energy storage due to its unique and excellent physical and chemical properties due to its special structure.In this thesis,based on the current social demand and trend,graphene-based composites were synthesized and applied by the microwave method in the cathode reaction of potassium ion batteries and fuel cells to optimize the performance of the materials in the application.The main research contents are as follows:1.A novel microwave-assisted rapid synthesis method of graphene in hollow nanospheres was proposed,which uses cheap organic small-molecule materials as reactants to convert to graphene in a short time.The prepared hollow graphene nanospheres have shown high capacity and good stability in electrochemical tests of potassium ion batteries.The synthesis method is fast,simple and inexpensive,providing a new method for the preparation of graphene.2.A method for preparing hollow graphene spheres supported palladium was proposed and used as an electrocatalyst for oxygen reduction.Due to the high cost and easy poisoning performance of Pt-based catalysts,the search for catalysts with high activity and stability has become the development direction of fuel cells.The design of hollow graphene spheres improves the problem of poor electrical conductivity of conventional two-dimensional graphene sheets due to easy accumulation.With the introduction of palladium,the activity of oxygen reduction reaction was improved to the activity level of commercial Pt/C while the cost was reduced.Meanwhile,it improves the disadvantages of Pt / C being easily poisoned and poor in durability,and the high stability was maintained even after a long time reaction.This method extends new research ideas in the field of electrochemical energy.3.A method for preparing manganese-nitrogen-doped graphene was proposed and applied to electrocatalytic oxygen reduction reaction.Manganese-supported graphene was synthesized in situ by microwave-assisted method,and manganese-nitrogen-doped graphene composite was formed by post-nitrogen doping.The addition of manganese in this material improves the graphitization degree of the carbon-based material and slows down its oxidative corrosion in the reaction.At the same time,through the synergistic effect of the manganese oxide at the active site and the Mn-N-C structure,the catalytic performance of the reaction is optimized,so that the material had excellent catalytic activity,methanol resistance and durability.