Preparation Of 3D Macroporous Graphene Composites By Hydrogen Bubble Dynamic Template Method And Their Electrochemical

Graphene has been widely studied for applications such as catalyst, energy, detection, electron device and energy storage due to its special two dimensional structure and outstanding physical chemical properties. However, hydrogen bonds and van der Waals force of graphene layers make it easy to stack, which limits its application scope. Therefore, it is important that the 2D nanoscale graphene can be self-assembled into order macrostructure, obtaining the regulated structure and morphology. Except for all kinds of excellent performance, we can gain access to more features and applications. This dissertation focuses on the synthesis and assembl of composite materials based on graphene. And it is also explored the assembly mechanism and applications of electrochemical properties in supercapacitors and electrochemical catalysis oxygen reduction. The main results are summarized as follows.(1) A general method for the fabrication of three-dimensional macroporous graphene electrode materials based on the electrochemically reduced deposition method, hydrogen bubble was used as the template for the preparation process on the different conductive substrates. The structure and morphology were controlled by the deposition time, potential and the concentration of surfactant. Combined with scanning electron microscope (SEM), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), electrochemical characterization methods, it is proved that the three dimensional graphene growth process, the degree of reduction, and the applications in the field of energy storage.(2) Based on the above experiments and the two-step electrochemical deposition method, pyrrole monomer is electrochemical polymerizated to fabricate graphene/polypyrrole composites. By changing the electrochemical deposition time, a series of different content ratio of graphene/polypyrrole composites were prepared and applied to the supercapacitors. Due to the benefit of the good conductivity of 3D MG and pseudocapacitance of PPy, the composites manifest outstanding area specific capacitance of 196 mF/cm2 at a 1 mA/cm2 and rapid charge-discharge capacity. In addition, the composite electrodes were successfully assembled into devices, which can make commercial red led luminous, offering the possibility for the practical life.(3) A series of nitrogen doped graphene materials are prepared by high temperature treatment of graphene/polypyrrole composites materials with changing the calcination temperature. The content and form of nitrogen was controlled by the temperature. Among them, nitrogen doped graphene of 800℃ followed four electron transfer process in the oxygen reduction catalyst reaction, with the maximum current density (5.56 mA/cm2) and the positive initial potential (-0.132 V vs Ag/AgCl).