Two-dimensional sandwich structured carbon nanosheets: facile fabrication and superior capacitive performance

Abstract

A facile and cost-efficient strategy was developed to generate two-dimensional (2D) sandwich structured carbon nanosheets (SSCNs) by utilizing graphene oxide sheets (GO) as shape-directing agent and the in-situ formed resorcinol-formaldehyde polymer (RF) as the carbon source. The key point of this efficient synthesis is the self-catalytic effect of resorcinol, which is the cornerstone for the construction of SSCNs. The obtained 2D SSCNs possess a graphene-like morphology and a novel porous carbon/graphene/porous carbon sandwich structure, where porous carbon layer (∼16 nm thick) is coated on both sides of graphene sheets. Such a unique 2D structure endows the SSCNs with a high specific surface area of 1496 m2 g−1 and a hierarchical pore structure, which is expected to shorten paths for fast electrolyte ion diffusion and provide large exposed surface for capacitive energy storage. As designed, the SSCNs delivered specific capacitance as high as 313 F g−1 (at 0.2 A g−1) and retained 272 F g−1 at high current density of 20 A g−1. More importantly, the SSCNs showed no apparent capacity decay after 10 000 cycles at 1 A g−1. This work paves the way to develop 2D carbon nanosheets for high-performance energy storage devices.