Preparation And Characterization Of Three Dimentional Porous Graphene

As an important member of carbon materials,graphene,is of unique two-dimensional honeycomb crystal structure closely packed by a single layer of carbon atoms.Extraordinary large specific surface area,excellent electrical conductivity and good mechanical properties are attributed to its unique structure.However,there exists strong Van der Waals force between the 2D graphene layers.The defects of reunion and accumulation have hindered its application in many fields,such as electrode materials,sensing materials and so on.Therefore,to assembly 2D graphene into 3D porous structure will be a good way to solve the problems in many applications.In this thesis,the redox of the natural graphite powder were investigated,and building 3D porous structure was studied.3D porous graphene was fabricated by hydrothermal cross-linking method and template method,respectively.X-ray diffraction?XRD?,scanning electron microscopy?SEM?,fourier transform infrared spectrometry?FT-IR?,thermal gravity analysis?TG?and BET methods were used to characterize the materials.Based on the modified Hummers' method,the graphene oxide GO1 and GO2 were prepared by controlling the reaction time during middle and high temperature stages,respectively.GO2 prepared at high temperature was of higher degree of crystallinity,exfoliation and corrugation phenomena.rGO-hydrothermal,rGO-hydrazine hydrate and rGO-glucose were prepared by hydrothermal,hydrazine hydrate and glucose reduction of GO2,respectively.Hydrothermal reduction was at 180 ? for 12h.Hydrazine hydrate reduction was at95 ? for 12h.And glucose reduction was at 95 ? for 12h.The oxygen-containing functional groups of the three rGO were mainly eliminated,a metallic luster appeared on the surface of the sheets and the thermal stability was obviously improved.The reduction effect of glucose is the best among them.Porous 3D rGO-hydrothermal and 3D rGO-CaCO₃ were built by hydrothermalcross-linking method and template method with GO2 as precursor,respectively.Hydrothermal cross-linking is at 180 ? for 12h.The template method used calcium carbonate?CaCO₃?as the template and glucose as the reducing agent,and the template was etched by hydrochloric acid solution.Both of hydrothermal method and template method could successfully assemble the 2D graphene into 3D porous structure.The pore size is mainly in mesoporous range,the specific surface area and the pore volume are obviously superior to rGO with lamellar structure.The specific surface area and the pore volume of porous 3D rGO-hydrothermal is better than that of porous 3D rGO-CaCO₃,the pore size is in a narrow range and more uniform.