A confinement strategy to prepare N-doped reduced graphene oxide foams with desired monolithic structures for supercapacitors

Abstract

It is a challenge to achieve pure graphene foams with a desired monolithic structure in order to take advantage of the excellent properties of graphene-based macroscopic assemblies. Here, we introduced a confinement fabrication strategy to prepare nitrogen doped reduced graphene oxide foams (NrGFs) through a one-step hydrothermal process. The melamine foam (MF) skeleton was removed during the hydrothermal reaction, and the NrGF retained its desired monolithic structure by the confinement of solution ionic strength. Due to the “roof-tile-like” microscopic morphology with high N-doping (9.88 at%), the free-standing graphene foam electrode exhibited excellent capacitive performance. The resulting NrGF-based symmetric supercapacitor displayed a remarkably enhanced specific capacitance of 260 F g⁻¹ at 0.1 A g⁻¹ and 173 F g⁻¹ at 20 A g⁻¹ in an aqueous electrolyte. Moreover, the facility of fabrication makes it a promising material in many contexts for large scale production, such as energy storage, environmental remediation and strain sensors. Furthermore, this synthesis strategy can be expanded to prepare other pure macroporous foams or composites by using different building blocks (such as CNTs and MXene).