The Controlling Preparation Of Porous Graphene

Porous graphene is a new kind of graphene derivative material which is obtained by pore-cutting treatment on graphene.Its unique porous structure makes it have a good application prospect in the fields of energy storage,filtration membrane and separation membrane.The size and density of pores are very important to the properties of porous graphene,which can affect the properties of porous graphene.In this thesis,different transition metal salts,noble metal salts and non-metal salts were selected to etch graphene.By controlling the kinds of salt,the structure of graphene oxide and etching conditions,a series of porous graphene materials with different pore structures were obtained.The conclusions are as follows: The graphene graphene is a new graphene-derived material obtained by engraving on graphene.Due to its unique porous structure,the graphene graphene provides a transport channel for the diffusion of ions and electrons,which can pass through these holes during lithium ion migration without bypassing the graphene sheet edge.Therefore,the graphene has a good application prospect in energy storage,filtration membrane and separation membrane.Porosity(pore size and density)is the most important structure in the graphene graphene,which affects many properties of graphene.Therefore,it is particularly important to control the microscopic pore structure of the graphene.In this paper,different transition metal salts,noble metal salts and non-metal salts were selected to analyze the etching of graphene.The structure of the graphitized graphene was controlled by controlling the addition type of salt,the structure of graphene oxide and the etching conditions.Controlled,a series of notched graphene materials with different pore structures were obtained.The conclusions obtained are as follows:1.The effects of transition metal,precious metal and non-metal salts on graphene etching structure were compared.The results showed that the types of etchants could affect the pore structure.For transition metals,Fe,Co,Ni salts can etch on graphene and form pores,while Cu,Zn,Mn salts have relatively poor etching effect.When Fe salt is selected as etchant,graphene is etched violently,even broken.Under the same conditions,Ni salt was chosen as etchant to produce a large number of pores with uniform size,and the diameter of pores was not more than 250 nm.Noble metal salts were also selected to etch graphene.The results show that the etching effect of noble metal salts is also directly related to their catalytic activity.However,non-metallic salts have no etching effect on graphene.At the same time,the effect of different anions on the etching effect of the same salt was also studied.The results show that the etching effect of the same salt is better than that of different anions.Nitrate etching effect is strong,acetate etching effect is second,and chlorine etching effect is worst.2.It was found that the structure of graphene oxide(including oxidation degree)also had some influence on the structure of porous graphene,and only the oxidation degree of graphene oxide was changed while other experimental conditions remained unchanged.The results show that the pore density of graphene with high degree of oxidation is higher than that of graphene with low degree of oxidation,and the pore diameter is smaller than that of graphene with low degree of oxidation.The influence of external factors(including etching temperature,pH value,heating rate and so on)on the structure of porous graphene was also studied.The results show that the etching effect is best when the pH value is 4,the etching temperature is high(800 °C);the etching effect is best when the heating rate is 5°C / min;Moreover,the effect of pH value on the degree of oxidation of graphene oxide and the specific unity of the effect on the etching effect,the more acidic groups on graphene oxide or the addition of acidic active sites in graphene oxide solution can improve the etching effect.At the same time,we also tested the performance of lithium-ion batteries with different pore structures,and found that the pore structure can affect the performance of lithium-ion batteries.3.Based on the previous etching results,we deduce the etching mechanism of graphene.It is considered that different metal salts affect the pore-forming process in the reaction system due to their metal activity,so we can adjust the pore density and size by changing the etchant,controlling the acidity of graphene oxide,pH value and other factors...