Hydrothermal Preparation And Performance Study Of Three-dimensional Graphene

The special structure of graphene which has only one atomic layer makes it have numerous excellent properties of mechanics; thermology; electricity; etc. Making graphene as a macro body can combine the excellent properties of graphene as nanometer material and the properties of macro porous material; obtaining a novel material which has low apparent density; large specific surface area; unique mechanical and electrical properties. Thus 3D graphene has great application prospect in many fields such electrode materials; hydrogen storage materials; biological sensors; catalyst carriers; nano-electronic devices; single molecule detectors; etc.In this thesis; the self-assembly of 3D graphene was realized by the use of giant graphene oxide as raw material. Natural flake graphite with particle size of 30 mesh was employed to prepare giant graphene oxide. The particle size of prepared giant graphene oxide came up to 100μm; the thickness of the giant graphene oxide was about 2.7nm; which revealed that giant graphene oxide had three atomic layers. There were a lot of oxygen containing functional groups c onnecting on the surface of giant graphene oxide. These hydrophilic groups facilitated the process of self-assembly in subsequent hydrothermal reaction.Using giant graphene oxide to achieve self-assembly in the period of hydrothermal reaction; 3D graphene hydrogels was synthesized successfully by controlling the temperature; time of hydrothermal reaction. Using freeze-drying method to make the hydrogel dry; the macroscopic size of dry 3D graphene block; was restricted by the size of the reaction kettle; and the block shrank after freezedrying; to be a cylinder whose size was Φ20x20mm. On the microscopic; the three-dimensional porous structure of graphene was made of graphene sheets. Winding; overlapping; stacking of graphene sheets was observed. 3D graphene had many performances such as low apparent density(11.2 mg/cm3); high rate(98.6%); some ability of conductive; good insulation ability and hydrophobic oleophilic characteristics.The influence factors of the self-assembly process was studied. The concentration of giant graphene oxide would affect the three-dimensional structure of graphene in the period of hydrothermal reaction. When increasing the concentration of giant oxide; the reductive degree of 3D graphene was reduced; and its porous structure were more compact. With the addition of metal ions; the connection points of graphene oxide increased in the self-assembly process; making 3D graphene pore size smaller.