The capacitance properties of nitrogen doped reduced graphene oxide obtained by using commercial protein powder as a nitrogen dopant

The restacking of graphene layers in chemically synthesized few-layered graphene can be reduced through approaches such as nitrogen doping, introduction of spacer materials in-between the graphene layers, and compositing with metal oxides. In the present study, graphene oxide (GO) is synthesized by a modified Hummers' method and reduced hydrothermally using different amounts of commercial protein powder, protineX. Also, GO is reduced hydrothermally in the absence of protineX for the purpose of comparison. ProtineX not only serves as a nitrogen dopant, but also as a precursor for the carbonaceous spacer. The effect of the presence of protineX during hydrothermal reduction of GO on the purity, amount of nitrogen doped, and the capacitance properties of RGO is systematically studied via various physico-chemical and electrochemical methods. On increasing the concentration of protineX during hydrothermal reduction of GO, the percentage of nitrogen doped in RGO and the surface area are found to increase. The specific capacitance of RGO is found to increase gradually from 115 F g(-1) to 235 F g(-1) at a current density of 1 A g(-1) on increasing the concentration of protineX from 0 to 20 wt% during the hydrothermal reduction of GO. On increasing the concentration of protineX further, the specific capacitance value of RGO is found to decrease.