Study On The Preparation Of Graphene Oxides By Different Natural Graphite And Their Adsorptive And Electrochemical Performances

Natural graphite has become one of the main raw materials for the large-scale preparation of graphene oxide and its related products,due to the abundant reserve and high stability.Therefore,in this paper,with four different types of natural graphite as the raw material,and based on the research of characteristic features,graphene oxides were synthesized through chemical oxidation.And the influence of degree of oxidation on the structures of oxidative products were investigated,as well as the adsorption and electrochemistry performance,which is of great significance to provide theoretical basis for the selection of the raw material,expanding the application fields of different types of graphite.Here are the main contents and results as below:(1)The measurements on natural graphite including vein graphite(VG),large flake graphite(LG),fine flake graphite(FG)and aphanitic graphite(AG)were carried out,and the four types of graphite possessed different graphitization degrees,structure defects and crystalline degrees,representing for the typical samples of different types of natural graphite.The results showed that the degree of crystalline decreased gradually from VG to AG,as well as the graphitization degrees.But the contents of 3R-graphite and oxygen atoms increased in this order.In addition,the cell volumes rose with the increasement of oxygen,leading in more structure defect.(2)With the four types of graphite as raw material,graphene oxides were synthesized through hydrous oxidation and ultrasonic exfoliation to investigate the the structural changes of oxidative products with various oxidation degrees.The results demonstrated that graphite with a low graphitization degree was easier to be oxidized to contain more abundant oxygen-containing functional groups on the surface,which could lead to better dispersion in the water and better exfoliation to form oxidative products with high structure defects.(3)Study on the adsorption performance of cationic blue on graphene oxides was conducted.The findings demonstrated that the adsorption was both an endothermic and spontaneous process.Due to the fact that aphanitic graphite(AG)with a low graphitization degree,GO-AG exposed more oxygen-containing functional groups on the surface to superior affinity to cationic blue,with better adsorption performance of 4248.79 mg/g in maximum adsorption capacity.(4)The results of electrochemical measurements on graphene oxides and reduced products demonstrated that the electrical double-layer capacitive characteristics of graphene oxides were poor,those of reduced products to remove functional groups were better.Due to the removal of oxygen-containing functional groups,low structure defect,as well as high restore degree and average size of the adjacent carbon atoms of sp~2 region,the specific capacitance of reduced graphene oxide prepared by large flake graphite(rGO-LG)was the highest,showing superior electrical double-layer capacitive characteristics.