Preparation Of Porous Graphene By Combustion Method And The Effect Of Substrate Under Positive Hydrogen Atmosphere Treatment On The Growth Of Graphene

Graphene is a typical two-dimensional crystal.It has excellent mechanical,thermal,electrical and optical properties and may be widely used in high-performance composite materials,biomimetic materials,biomedicine,automotive energy and other fields in the future.At present,various forms of graphene are hotspots in industry and academia,including graphene aerogels,nanoporous graphene sheets and large-area single-layer graphene.The preparation of high quality graphene materials is the premise of its application,and it is also the main content of this paper.This paper mainly includes two aspects:first,the preparation of nanoporous graphene sheets by combustion method and its application in supercapacitors;secondly,the improvement of domestic commercial copper by positive pressure(above atmospheric pressure)annealing of copper foil.The quality of the large-area single-layer graphene grown on the foil was verified by preparing graphene-silicon solar cell.The first chapter is the introduction,which mainly introduces the basic concept of graphene and the preparation methods,research status and application prospects of various forms of graphene,and clarifies the research motive of this paper.The second chapter describes the preparation of nanoporous graphene sheets and their applications in supercapacitors.In the third chapter,the optimization of the crystal orientation of copper foil by positive pressure annealing is studied to improve the quality of graphene grown on domestic commercial copper foil,and the cost of mass production of graphene is reduced.The fourth chapter is the summary and outlook of the work of this paper.The specific contents of the second to third chapters are as follows:Chapter 2:Nanoporous graphene has the characteristics of low electrical resistivity,high specific surface area and high porosity.It is an excellent supercapacitor electrode material.This chapter focuses on the preparation of porous graphene.The graphene oxide aerogel was contacted with a heating table at a specific temperature(200?300 ?).The graphene oxide aerogel undergo a severe combustion reaction in a very short time,generating graphene sheets containing a large number of nanopores.The obtained graphene material has a specific surface area of up to 536 m2·g-1,and the number of graphene layers was less than 5,and the pore size distribution on the graphene ranged from 0.4 to 2 nm.The prepared 3D graphene aerogel was used as an electrode of a supercapacitor,and its specific capacitance was measured to be as high as 245 F·g-1.The electrode has good cycle stability(after 12,000 charge and discharge cycle tests,the specific capacitance retention rate is as high as 96.9%).Chapter 3:Laboratory chemical vapor deposition(CVD)preparation of large-area single-layer graphene is generally based on Alpha's high-purity copper foil.Under the same conditions,it is difficult to prepare high-quality large-area single-layer graphene with domestic commercial copper foil as a substrate.Substrate annealing is a common way to prepare large-area high-quality graphene.We found that positive pressure annealing of copper foil could significantly broaden the growth window of large-area single-layer graphene before graphene growth.Annealing pressure and time have a great influence on the growth of graphene,which we have studied in detail.The experimentally prepared large-area graphene monolayer rate is over 95%,the sheet resistance is about 500 ?/?,the carrier mobility is 2000-3000 cm2·V-1 ·s-1,and the light transmittance is 97.24%.The graphene-silicon solar cell thus produced has a photoelectric conversion efficiency of 4.99%to 5.62%.