Optimize reduction methods of graphene oxides for enhanced electrochemical properties
Graphene and related materials have attracted great interest due to the excellent properties as electrical conductor. Thus various methods have been reported to produce high quality graphene and the most widely used method is the oxidation of graphite to graphene oxide followed by reduction. The objective of this thesis research is to optimize the graphene oxide synthesis and reduction process, finally obtain graphene materials with enhanced electrochemical properties. The initial graphene oxide reported in this thesis were produced followed modified Hummers Method and were used as precursor of graphene materials synthesis. In the following optimization process, we tried different reaction conditions and made a few changes to the origin recipe of graphene oxide to improve its properties as insulator. Afterward, a combination of four most common reduction methods was proposed to conclude the most effective two-step reduction procedure and then optimized with better controlled conditions. To evaluate the electrochemical performance, final produced graphene materials were tested by Cyclic voltammetry, Ultraviolet and Visible Spectroscopy, X-ray diffraction, Raman spectrum and Scanning Electron Microscopy analysis. GO reduced by sodium borohydride followed by hydrazine treatment showed higher electrochemical properties than the other procedures in both alkaline (162 F/g) and acid (164 F/g) electrolytes. Furthermore, a clear view of structure change can be observed during both oxidation and reduction, which conform the successful of optimized reaction procedure.