A scalable dual activation strategy to construct heteroatom-doped graphene-reinforced porous carbon with tunable pores for supercapacitors

The development of scalable synthesis methods for heteroatom-doped carbon with tailored pore structures remains a significant challenge. In this study, we present a dual-activation strategy employing KOH and K₃PO₄ to fabricate heteroatom-doped graphene-reinforced porous carbon with tunable pores (1–4 nm) through electrostatic self-assembly of chitosan and graphene oxide. The optimized material demonstrates a large specific surface area (2672.39 m² g⁻¹) with dominant (1–4 nm) pores (V_{(1-4) nm} = 1.23 cm³ g⁻¹, V_{(1-4) nm}/V_t = 77.36 %) and favorable heteroatom configurations. Electrochemical tests in a three-electrode system demonstrated exceptional performance, including a specific capacitance of 371 F g⁻¹ at 0.5 A g⁻¹, excellent rate capability (266 F g⁻¹ at 100 A g⁻¹), and remarkable cycling stability (98.2 % retention after 50,000 cycles) in 6 M KOH. Symmetric supercapacitors deliver an energy density of 38.9 Wh kg⁻¹ in 1 M TEABF₄/AN electrolyte while maintaining 98.5 % capacity retention over 20,000 cycles in 6 M KOH. This study provides novel insights for designing carbon materials with synergistic pore structure and heteroatom engineering for advanced energy storage.