In the present work, we used charge-bearing nanosheets as building blocks to construct a binary composite composed of NiCo₂O₄ and reduced graphene oxide (RGO). Co–Ni hydroxides intercalated by p-aminobenzoate (PABA) ion and graphite oxide (GO) were exfoliated into positively charged hydroxide nanosheets and negatively charged graphene oxide nanosheets in water, respectively, and then these oppositely charged nanosheets were assembled to form heterostructured nanohybrids through electrostatic interactions. The subsequent thermal treatment led to the transformation of the hydroxide nanosheets into spinel NiCo₂O₄ and also to the reduction of graphene oxide. The as-obtained NiCo₂O₄–RGO composite exhibits an initial specific capacitance of 835 F g⁻¹ at a specific current of 1 A g⁻¹ and 615 F g⁻¹ at 20 A g⁻¹. More interestingly, the specific capacitance of the composite increases with cycling numbers, reaches 1050 F g⁻¹ at 450 cycles and remains at 908 F g⁻¹ (higher than the initial value) after 4000 cycles. The high specific capacitance, remarkable rate capability and excellent cycling ability of the composites mean that they show promise for application in supercapacitors. Comparison with the capacitive behavior of pure NiCo₂O₄ and NiCo₂O₄ mechanically mixed with RGO displays the importance of the self-assembly of the nanosheets in making a wide range of graphene-based composite materials for applications in electrochemical energy storage.

Three-dimensional (3D) lamellar SnO ₂ is grown on a carbon cloth (CC) substrate (denoted as 3D lamellar SnO ₂ /CC) through hydrothermal reactions and subsequent thermal treatments.

Redox-active covalent organic frameworks (COFs) are an emerging class of energy storage materials due to their notably abundant active sites, well-defined channels and highly surface areas. However, their poor electrical conductivity and low electrochemical accessibility to the active sites have severely restricted their practical applications. Here, we demonstrate the fabrication of an anthraquinone-based COFs/graphene composite aerogel (DAAQ-COFs/GA) electrode through electrostatic self-assembly between negatively charged graphene oxide (GO) nanosheets and modified positively charged nanoflower DAAQ-COFs. The obtained freestanding electrode with a 3D crosslinking conductive network efficiently addresses the limitations of sluggish electron transfer and low utilization of the active sites within the organic framework. Owing to the hierarchical porous structure and the rapidly faradaic reactions of redox sites, the electrode exhibits a high specific capacitance of 378 F g⁻¹ at 1 A g⁻¹ and fast kinetics with about 93.4% capacitive contribution at 3 mV s⁻¹. Furthermore, the binder-free DAAQ-COFs/GA and pure graphene aerogel (GA) electrode are assembled into an asymmetric supercapacitor (ASC), showing an energy density up to 30.5 W h kg⁻¹ at a power density of 700 W kg⁻¹. This work demonstrates the great potential of developing high-performance COF-based energy storage devices.