Synthesis of Carbon Nanosheets and Nitrogen-Doped Carbon Nanosheets from Perylene Derivatives for Supercapacitor Application

The development of an economical, eco-friendly, and easy method for the production of carbon nanosheets and heteroatom-doped carbon nanosheets has been a challenge for material scientists. In this study, we developed a method for the synthesis of carbon nanosheets (CNS) and nitrogen-doped carbon nanosheets (NCNS) of high quality from organic compounds. We exploited the electrostatic interaction among ionic crystals (NaCl in the present case) and polarized aromatic molecules (3,4,9,10-perylene tetracarboxylic dianhydride (PTCDA) and 3,4,9,10-perylene tetracarboxylic diimide (PTCDI) in this work) to obtain uniform coverage of the latter over the surface of the ionic crystal. This NaCl-PTCDA/PTCDI assembly, on pyrolysis at 700 °C followed by washing with water, yields high-quality CNS and NCNS depending on the aromatic precursor employed. The sheets obtained consist of minimum 2–3 layers (～2 nm) as observed from atomic force microscopy. The process demonstrated is highly scalable, economical, eco-friendly, nonhazardous, and relatively fast. Moreover, the NCNS derived from PTCDI is applied for energy storage application by fabricating an electrochemical capacitor that exhibits an area normalized capacitance of 23 μF cm–2 in 0.5 M H2SO4, which is the same as that reported for the single-layer nitrogen-doped graphene. Furthermore, an NCNS–carbon black composite is prepared and applied to a high-performance solid-state supercapacitor that exhibited a capacitance of 300 mF cm–2