Constructing graphene-based heterostructures with large interfacial area is an efficient approach to enhance the electrochemical performance of supercapacitors but remains great challenges in their synthesis. Herein, a novel ultra-small amorphous Fe₂O₃ nanodots/graphene heterostructure (a-Fe₂O₃ NDs/RGO) aerogel was facilely synthesized via excessive metal-ion-induced self-assembly and subsequent calcination route using Prussian blue/graphene oxide (PB/GO) composite aerogel as precursors. The deliberately designed a-Fe₂O₃ NDs/RGO heterostructure offers a highly interconnected porous conductive network, large heterostructure interfacial area, and plenty of accessible active sites, greatly facilitating the electron transfer, electrolyte diffusion, and pseudocapacitive reactions. The obtained a-Fe₂O₃ NDs/RGO aerogel could be used as flexible free-standing electrodes after mechanical compression, which exhibited a significantly enhanced specific capacitance of 347.4 F·g⁻¹ at 1 A·g⁻¹, extraordinary rate capability of 184 F·g⁻¹ at 10 A·g⁻¹, and decent cycling stability. With the as-prepared a-Fe₂O₃ NDs/RGO as negative electrodes and the Co₃O₄ NDs/RGO as positive electrodes, an all-solid-state asymmetric supercapacitor (a-Fe₂O₃ NDs/RGO//Co₃O₄ NDs/RGO asymmetric supercapacitor (ASC)) was assembled, which delivered a high specific capacitance of 69.1 F·g⁻¹ at 1 A·g⁻¹ and an impressive energy density of 21.6 W·h·kg⁻¹ at 750 W·kg⁻¹, as well as good cycling stability with a capacity retention of 94.3% after 5,000 cycles. This work provides a promising avenue to design high-performance graphene-based composite electrodes and profound inspiration for developing advanced flexible energy-storage devices.

As a promising graphene analogue, two-dimensional (2D) polymer nanosheets with unique 2D features, diversified topological structures and as well as tunable electronic properties, have received extensive attention in recent years. Here in this review, we summarized the recent research progress in the preparation methods of 2D polymer nanosheets, mainly including interfacial polymerization and solution polymerization. We also discussed the recent research advancements of 2D polymer nanosheets in the fields of energy storage and conversion applications, such as batteries, supercapacitors, electrocatalysis and photocatalysis. Finally, on the basis of their current development, we put forward the existing challenges and some personal perspectives.