Synthesis and characterization of graphene oxide from locally mined graphite flakes and its supercapacitor applications

Abstract

Graphite is a mineral mined from different parts of the world which including Africa. It can be used or converted into different carbon materials such as exfoliated graphite, graphene, Graphene Oxide (GO), graphene nano platelets, carbon nano tubes, carbon onions among others by chemical or mechanical methods. The locally mined graphite flakes was converted to GO using chemical methods known as Hummer’s oxidation method (HM). This method was also compared with other modified Hummer’s methods by altering the conditions and the materials used. In the modified Hummer’s method 1 (MHM1) a ratio of 9:1 of H2SO4/H3PO4 was used. While the modified Hummer’s method 2 (MHM2) a reflux process was employed. The synthesized GO materials were characterized by different techniques such as UV–Vis spectroscopy, FTIR, SEM-EDX, XRD and electrochemical analysis. The morphology, functional groups, different bonds, elemental composition, crystallographic structure and energy storage applicability of the GO were examined. The techniques confirmed formation of functional groups like C–O, Cdouble bondO and the C/O ratio in the materials. The electrochemical characterization performance of materials produced the highest specific capacitance of 211.2 ​F/g with a current density of 0.5 ​A/g and the specific energy of 7.33 ​Wh/kg.