Three-dimensional graphene-based macro- and mesoporous frameworks for high-performance electrochemical capacitive energy storage

Three-dimensional graphene-based frameworks (3D-GFs) with hierarchical macro- and meso-porous structures are presented. The interconnected macropores are derived from hydrothermally assembled 3D graphene aerogels (GAs), while the mesopores are generated by the silica networks uniformly grown on the surface of graphene. The resulting 3D-GFs exhibit narrow mesopore size distribution (2-3.5 nm), high surface area, and low mass density. These intriguing features render 3D-GFs a promising template for creating various 3D porous materials. Specifically, 3D GA-based mesoporous carbons (GA-MC) and metal oxide hybrids (GA-Co₃O₄, GA-RuO₂) can be successfully constructed via a nanocasting technology. Benefiting from the integration of meso- and macroporous structures, 3D GA-MC manifests outstanding specific capacitance (226 F g^-1), high rate capability, and excellent cycling stability (no capacitance loss after 5000 cycles) when it is applied in electrochemical capacitors.