| Graphene,as the first two-dimensional nanomaterial,has received continuous attention and research since its discovery in 2004.Benefit from its superior performance in mechanics,electricity,thermals,optics,etc.,it has great application value in many fields such as materials science,micro/nano processing,electronic devices,energy,biomedicine and so on.It is considered as a revolutionary material in the future.However,due to the limitations of preparation techniques,the size of graphene is generally small,which limits its large-scale application in real life.The effective way to solve the current problems is to assemble the micro sized graphene sheets into macro materials,such as one-dimensional graphene fibers,two-dimensional graphene paper/films,and three-dimensional graphene assemblies.Through this strategy,the assembled macroscopic materials can obtain certain graphene characteristics,and the properties of the fabricated macroscopic materials are often closely related to the preparation methods.Among them,the electrostatic spray deposition technology has become a better method for material preparation due to its advantages of simple operation,high material utilization and mass production.In this paper,two macroscopic materials,graphene fabric and hollow graphene fiber prepared by electrostatic spray deposition technology are introduced.These two macroscopic materials not only inherit the excellent electrical conductivity of graphene,but also have laudable flexibility,which has broadened new methods and ideas for the preparation and application of graphene flexible materials.To this end,the following two works have been carried out:In the third chapter,a flexible graphene fabric composite material prepared by electrostatic spray deposition technology is introduced.After simply adding electrodes,the graphene strain sensors in two directions and pressure sensors with different layers can be made.Among them,the resistance change of the strain sensors is negatively correlated with the applied strain,which is contrary to the positive correlation characteristics of most sensors,making it maintain a high sensitivity even under a large range of strain.The sensing performance of both strain sensors and pressure sensors has been deeply studied and characterized.For the strain sensors,the maximum GF factor is up to 153.5,the stretching range is 0-40%,and it has preferable recoverability and reliability.For the pressure sensors,the maximum GF factor is up to 716.8 kPa-1,and the detection range is 0-14 kPa,with rapid response,high repeatability and stability.Finally,the two types of graphene sensors are fixed to different parts of human body respectively.After testing,it is found that the two types of sensors can detect the movement state and vital signs of the human body in real time,indicating that they have certain application value and development potential in wearable electronic devices and flexible sensors.The fourth chapter focuses on a flexible hollow graphene fiber prepared by electrostatic spray deposition technology.Compared with other preparation methods of hollow graphene fiber,this method is simple to operate and has a high template removal rate.The hollow graphene fiber produced by this way has a multi-channel structure,larger specific surface area,and can be used for loading functional materials.The reduction degree of graphene fiber has been characterized and analyzed by Raman test and XPS test,and the conductivity of graphene fibers with different reduction degree at different temperatures has been characterized and analyzed by PPMS.In the end,some applications have been developed.Because of its outstanding flexibility and conductivity,the LED has been light up successfully by using it as a flexible wire to access the circuit.Owing to its high specific area,the photoelectric test has been applied by loading the functional material titanium dioxide,showing remarkable photoelectric response characteristics. |
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