Controlled Structure Regulation Of Graphene And Its Electronic Properties

Recently,graphene has attracted much attention due to its unique electrical,mechanical and chemical properties.Structural regulation is crucial to the practical application of graphene.Herein,we controlled regulate the graphene structure and study its application in the field of novel sensors.The main contents of the thesis are as follows:1. Chemical vapor deposition（CVD）prepared graphene on Copper foil was regulated by（NH₄）₂S₂O₈ etching to yield graphene-graphene scrolls（G/GS）hybrid films.The demo piezoresistive sensor made of the as-prepared G/GS hybrid films owned high sensitivity(3.5 k Pa^-1),fast response time（50/30 ms）,and good reproducibility during>1000loading-unloading cycles（resistance change rate less than 2.5%after 1000 cycles）.In addition,the sensitivity(3.5 k Pa^-1)of the lower stress region（0-0.5 k Pa）was higher than that reported in most literatures.In addition,we also tested the applications of the G/GS pressure sensor for human motion detection based on its response to periodic stress and bending force and demonstrated its great potential application in smart wearable devices.2. The structure of graphene oxide（GO）was adjusted by strong acid oxidation cutting method,and GO quantum dots（GOQDs）with a size of less than 10 nm and almost single layer were prepared.GOQDs not only has the inherent high conductivity and excellent mechanical properties of graphene,but also has a higher specific surface area at the nanoscale.Electrospinning can produce fibers with diameters of tens to hundreds of nanometers.The products have high porosity,uniform diameter distribution and diversified compositions.We break the structural limitations of ordinary GO sheets and combine infrared and XPS characterization methods and prove that the number of functional groups in GOQDs is-OH>-COOH.Therefore,it is envisaged to use electrospinning to crosslink GOQDs with small molecules or long chain molecules in order to obtain high elasticity,high porosity,high specific surface area and a large number of conductive channels GOQDs composite fiber film,building a high-performance piezoresistive sensor.