Low Temperature Synthesis And Application Of Graphene Based On Solid Carbon Source

Graphene has attracted numerous interests owing to its outstanding electrical properties,excellent thermodynamic stability and mechanical stiffness.Nowadays,with the rapid development of nanocomposites,energy storage devices and intelligent sensing devices,the synthesis and application of graphene have been greatly promoted.Reducing graphene oxide to graphene is a low-cost and simple synthesis method,which is promising to be one of the routes for industrial graphene preparation.At the same time,the rearrangement of amorphous carbon extracted from solid carbon sources provides another pathway.In this thesis,the low temperature synthesis of graphene based on solid carbon source was studied.Amorphous carbon deposited by magnetron sputtering as carbon source,and graphene oxide?GO?was used to synthesize graphene by atom rearrangement and plasma-induced GO reduction,respectively.The optimal preparation process of graphene was discussed,its internal mechanism was analyzed and the application of stress sensor based on reduced graphene oxide?RGO?was also discussed.Firstly,the plasma-assisted magnetron sputtering was used to deposit amorphous carbon as the carbon source of graphene growth and the influence of annealing temperature and introduction of Ni catalytic metal on the growth and quality of graphene was mainly investigated.It was found that metal catalyst Ni played a crucial role in the preparation of graphene with amorphous carbon through comparative experiments.The annealing temperature profoundly influenced the phase of carbon.At an optimal annealing temperature of 550?C,I_D/I_G is 0.5,showing a lower defect at this annealing temperature.Besides,graphene will inversely dissolve into metal when temperature is too high?>600?C?.At the annealing temperature 600?C,the three characteristics of graphene peak D,G,2D peak does not exist.The process of preparing graphene from amorphous carbon is also accompanied by the change of carbon phase,from amorphous carbon to graphitic phase.And the internal mechanism is the effect of metal induced crystallization.Plasma-assisted sputtering of amorphous carbon produced less structure defects.Plasma is beneficial to the preparation of high-quality graphene by magnetron sputtered amorphous carbon.Plasma also plays an important role in the synthesis of graphene from GO as a cheap carbon source.In this thesis,the effects of different plasma reducing atmosphere on the reduction effect of GO were analyzed,and external bias voltage was introduced to regulate the internal electric field of the plasma innovatively.Experimental results showed that the reduction effect of N₂-H₂ plasma was better than that of sole H₂ plasma.Moreover,when-35V bias was applied,there is a higher reduction level of GO than that of H₂ plasma.In addition,the bias can accelerate the ions in the plasma,so that the ions in the plasma,especially those close to the graphene oxide surface,have higher kinetic energy,which in turn can tune the nitrogen doping of graphene to a certain extent.The optical emission spectroscopy?OES?technique was used to diagnose the plasma and to analyze the mechanism by which graphene oxide was reduced.Reduced graphene oxide based flexible stress sensors were successfully fabricated by in-situ reduction of GO on PDMS substrates using plasma technology.The sensitivity of the sensor is as high as 24.Finally,the sensor is applied to different position of human skin surface for motion monitoring,and displays an excellent performance and an enormous prospect.