Modulating the supercapacitance of N-doped reduced graphene oxide synthesized using water-soluble inorganic precursors

Controlling nitrogen functionalities in graphene are crucial for high-performance supercapacitors. In this study, we report the scalable synthesis of nitrogen-doped reduced graphene oxide (N-rGO) via a hydrothermal process using readily available inorganic precursors in an aqueous phase, enabling controlled manipulation of nitrogen functionalities. The optimized N-rGO (GO:aqueous NH 3 = 1:6) exhibits a areal capacitance of 0.4 F cm −2 at a scan rate of 5 mV s −1 . In a symmetric two-electrode system, N-rGO delivers a high specific capacitance of 532 F g −1 , along with an energy density of 41 Wh kg −1 and a power density of 375 W kg −1 at 0.5 A g −1 , with a capacitance retention of ∼78% after 10,000 cycles at 1.96 V. These performance metrics are attributed to an optimal defect concentration combined with a high proportion of amino and pyrrolic nitrogen functionalities. Quantum capacitance calculations reveal an enhanced electronic density of states near the Fermi level, thereby improving charge storage performance.