Nanoporous graphitic carbon materials: largely elevating the capacitive performance by simple incorporation of redox additive

We demonstrate a synchronous carbonization and graphitization process for producing nanoporous graphitic carbon materials, using ammonium iron (III) citrate as sole starting material. The temperature has a crucial role in the determination of carbon structure, graphitization as well as porosity. The carbon sample obtained at 800 °C has delivered the largest capacitance, whereas the one at 1000 °C is the lowest, primarily due to its smallest porosity incurred by the structure collapse. More importantly, 4-(4-nitrophenylazo) resorcinol serving as redox additive has been incorporated into KOH electrolyte. As a result, when designating the redox additive concentration as 3, 6, and 9 mmol L−1, the corresponding capacitances can reach up to 59.2, 105.8, and 141.0 F g−1, which are almost the 1.78, 3.17, and 4.23 times than the one without redox additive. Thereby, the present 4-(4-nitrophenylazo) resorcinol can serve as simple but effective redox additive for remarkably improving the capacitive performance.