The Research On Controllable Synthesis Of Graphene By Chemical Vapor Deposition Method And Its Applications

Chemical vapor deposition method is universally employed to synthesis high-quality and large-area graphene,during which there are many detailed issues that worthy of more attentions.Specifically,the number of graphene layer is highly linked with the reaction condition parameters including carbon sources,atmosphere,pressure,etc.Thus,whether graphene with varied layers can be directly obtained by controling these parameters,which is essencially different from graphene superimposed layer by layer? In addition,since graphene grown on the metal surface is an epitaxial growth procedure,can graphene with variable designed shapes be produced by rationally changing the type or morpholoy of the catalytic metal substrate?According to aforementioned concepts and understaning,here,graphenes of 1-7 layers were first synthesized,and the detailed influencesof exprimental paprameters on graphene growth were investigated.Moreover,A range of characterization technologies,such as scanning elecron microscopy(SEM),transmission electorn microscopy(TEM),Atomic Force Microscope(AFM)and so forth,were conducted to monitor the layer,morphology and crystal quality of graphene prepared under different experimental conditions,thus gaining a reletively clear insight into the effect of particular experimental parameters on the quality and layer of graphene.Based on the graphene with varied layers obtained,their applications in an inhomogeneous strain sensor and schottky junction solar cells were explored.It was found that the 2D band in graphene Raman specturm is a powerful tool for sensing the inhomogeneous metal phase transition.The shift number of 2D band can quantitatively display the degree of strain.It is also indicated that the graphene-silicon schottky junction solar cells fabricated with graphene of different layers exhibit different light response,among which four-layer graphene shows best performance.Considering that graphene grown on the metal surface is an epitaxial growth procedure,we broaden the size of the cataltytic metal substrate from two demension to three demension and a variety of three demensional metal substrates were introduced,with the hope of elucidating the influences of metal type and three demensional morphology on graphene growth.It is proved that due to high activity of nanoporous copper,the preparation temperature of graphene is lowered to 800? and reaction time is shorten to 30 seconds.Furthermore,an investigation of the surface enhanced Raman effect of the nanoporous graphene was performed by using R6 G as the probe molecule.The results indicates that nanoporous graphene has a great potential as SERS substrate that is better than nanoporous copper flake,and even superior to single layer graphene.Finally,nickel foams and copper foams were utilized as the catalytic substrates to prepare three-dimensional graphene foam.In order to further enrich nanostructures of graphene foam,two-step method was used to synthesize bamboo-like carbon nanofiber on graphene foam with diameters ranging from 50-600 nm.In another experiment,smaller pores were successfully fabricated on the surface of graphene foam,the pore size ranged from a few hundred nanometers to about 1 micron.These structure-modified graphene foams are expected to achieve broader applications.