Exploiting the chemistry of redox active compounds to enhance the capacitance of reduced graphene oxide

•Addition of redox additives is a facile strategy to improve the capacitance of RGO.•Reversible redox reaction of quinone enhances the capacitance in H2SO4-Q electrolyte.•Shuttling of iodide and triiodide ions enhances the capacitance in H2SO4-KI.•In H2SO4-NaI electrolyte, formation of iodine also enhances the capacitance.•Slow kinetics of redox reactions slightly compromises the rate performance.