The Preparation Of Graphene Microbeads And The Study Of Its Electrochemical Performance

In recent years,three-dimensional stacking structures of graphene,such as fibers,foams,frameworks,and spherical objects and so on,have aroused extensive attention.Among those structures,spherical objects are interesting and challenging.Up to now,the spherical objects of graphene have been fabricated by methods involving aerosol spray pyrolysis,carbon source,hydrothermal process,chemical vapor deposition,template assisted method,microfluidic technology and emulsion process and so forth.In this paper,we used a simple emulsion device and a homemade droplet-based microfludic equipment to fabricate graphene beads,and chose graphene oxide(GO)as the raw material and dimethyl silicone oil as the oil phrase.To keep the spherical shape stable,polyvinylpyrrolidone(PVP)served as the binder of GO sheets.Meanwhile,we have research the electrochemical properties of the graphene beads.The detail works were summarized as the follows:1.Graphene beads were fabricated via a simple emulsion process by using PVP as the binder of GO sheets to keep spherical shape stable.The stirring rate played an important role in the diameters of graphene beads and internal morphologies.Through the three-step preoxidition and calcinations process,the graphene beads with wrinkled structure were obtained.2.A modified microfluidic device was designed to fabricate three-dimensional solid or hollow graphene beads.PVP was used as the binder of GO sheets and an efficient means of increasing the capacitance and stability due to the pseudofaradaic effect.In the droplet microfluidic process,the concentration of dispersed phase,the size of droplets and the methods of solidification play an important role in constructing the morphologies and structures of GO sheets.3.The porous graphene and porous carbon microbeads were also prepared by adding colloidal silica particles in the dispersed phase of GO and PVP,respectively.