High‐Density Co and N Dual‐Doping in Self‐Supporting 3D Graphene Aerogel for Synergistically Enhanced Supercapacitor Performance

Graphene aerogel (GA) is characterized by its 3D interconnected conductive network, ultra-high specific surface area, and exceptional chemical stability, and has emerged as the preferred skeleton material for supercapacitors. However, the double-layer mechanism that exclusively relies on physical ion adsorption presents challenges in further enhancing its specific capacitance. Fortunately, cobalt (Co) exhibits multiple valence states and possesses a high theoretical specific capacitance. This characteristic not only enhances the capacity for ion adsorption on its surface but also introduces redox-active sites, thereby significantly contributing to the achievement of high pseudocapacitance. In this study, we successfully synthesized Co/nitrogen (N) co-doped graphene aerogel (Co-NGA) by a one-step hydrothermal co-doping strategy. By leveraging the coordination capability of N atoms within the graphene lattice, the atomic-level dispersion and stable anchoring of Co atoms were achieved. The synergistic effect resulting from the combination of a porous structure and Co/N co-doping endows this aerogel with outstanding electrochemical performance in supercapacitor applications. At a current density of 1 A/g, the specific capacitance of 5.6%Co-NGA achieves an impressive value of 2092 F/g, significantly surpassing that of NGA (390 F/g) and GA (239 F/g). Furthermore, an asymmetric supercapacitor assembled using 5.6%Co-NGA and activated carbon (AC) demonstrates great energy storage capabilities. This work presents a promising strategy for designing high-performance capacitor electrode materials and highlights the promising application prospects within the realm of supercapacitors.