Synthesis of sandwich-like graphene@mesoporous nitrogen-doped carbon nanosheets for application in high-performance supercapacitors

Nanostructured mesoporous carbon materials have been an attractive material for electrochemical energy storage in the recent decades. However, the controllable synthesis of two-dimensional mesoporous carbon with tunable thickness and desired pore structure is highly challenging. Here, a series of graphene@mesoporous nitrogen-doped carbon (denoted as G@mesoNC) core-shell structured nanosheets with tunable thicknesses have been fabricated via a sample hydrothermal method by using cellulose as the green and cheap carbon precursor. The resultant G@mesoNC nanosheets exhibit a distinct sandwich-like structure with tunable thicknesses (from 10 to 30 nm), a large surface area (562 m² g^-1), a narrow pore size distribution (2.3 nm) and a high nitrogen content (7.95%). Significantly, when being used as the electrode for supercapaciors, the resultant G@mesoNC nanosheets showcase a high specific capacitance of 264 F g^-1. Most importantly, there is no substantial capacitance decay after 2500 cycles, indicating the perfect cyclic stability of G@mesoNC nanosheets. Our method paves a new way for synthesizing carbon electrodes for energy storage.