Study On The Preparation Of Graphene By Ultrasonic Peeling-chemical Reduction Method

The graphene material has wide application prospect in many fields because of its unique excellent mechanical,optical,thermal and electrical properties,et al..Among the many methods of preparing graphene,the chemical reduction method is inexpensive and simple to operate,and has the most potential for large-scale production.However,there are too many steps in this method,the cleaning process is repeated and cleaning difficult to lead to the preparation of cumbersome and cumbersome issues.Therefore,simplifying the process of reducing the preparation time is an important way to improve the preparation efficiency of graphene.In this paper,the three processes of traditional chemical oxidation reduction method were reduced to two processes by ultrasonic stripping-chemical reduction method,which shortened the preparation time and improved the efficiency.Tea polyphenols were used as reducing agent to make the reaction process and reaction products more green.Using N,N-dimethylacetamide(DMAc)and water mixture as reaction solvent and dispersant.In order to ensure the quality of graphene as much as possible is excellent,this paper explores the graphite powder,the content of tea polyphenols,ultrasonic time,ultrasonic power and VDDMAc<VH2O influence on the properties of graphene.And the properties of graphene were analyzed by X-ray photoelectron spectroscopy,Raman spectroscopy and infrared spectroscopy,et al.The experimental results and conclusions are as follows:(1)The traditional method of chemical oxidation reduction method containing oxidation,stripping,reduction of three stages.In this method,the physical ultrasonic is used to overcome the van der Waals oxidized graphite and the graphene sheet.At the same time,tea polyphenols reduced oxygen containing groups of graphite oxide and graphene oxide.The physical and chemical reactions can be carried out without conflict at the same time,so that the stripping phase and the reduction phase in the traditional chemical oxidation reduction process are simultaneously carried out.The reaction time is shortened and the production efficiency is improved,which provides a new method for the industrialized production of graphene.(2)Graphite powder,ultrasonic power,ultrasound time,the value of VDMAc/VH2O and the dosage of reducing agent are the factors that affect the properties of graphene products.Graphite powder particles smaller,its surface area is greater,more susceptible to oxidation,so that the degree of oxidation of the precursor of graphite oxide high is difficult to be completely.Thus,the reduction degree of graphene obtained lower,defect value is larger.With the increase of ultrasonic treatment time and the increase of ultrasonic power,the reduction degree of graphene can be improved,and the reduction is almost completed under certain conditions.With the increase of the amount of tea polyphenols,the reduction of graphene products increased first and then stabilized,while the thermal stability of graphene products increased slightly after rapid enhancement.And the amount of tea polyphenols required to achieve the strongest degree of reduction and the strongest thermal stability is the same.Since the reduction reaction is basically completed at this dose,the thermal stability of the product is also strongest,but with the increasing quality of tea polyphenols,the residual polyphenols adsorbed on the graphene products lead to the thermal stability of the product reduce.The dispersion of the graphene in the reaction solution increases first and then stabilizes with the increase of the VDMAc/VH2O value,and the dispersion of graphene in the reaction solution is the key to determine the degree of product reduction.In the reaction process,graphite oxide,graphene oxide and graphene were also present in the reaction solution.The higher the dispersity,the more difficult the graphene to agglomerate with graphite oxide and graphene oxide.Therefore,it will not hinder the contact between tea polyphenols and oxygen-containing functional groups,and the reaction is more thorough.(3)According to the phenomena of the oxygen containing functional group OH in all the graphene products prepared under the different reaction conditions,the reduction mechanism of C=O was proposed.That is,the graphite oxide containing C=O of benzoquinone structure and tea polyphenol components of epigallocatechin gallate(EGCG)reducing reaction,generate chemical properties of OH containing stable substances on phenol structure.