Fused heteroaromatic benzothiazoles functionalized nitrogen-doped graphene by non-covalent bonds for high-performance supercapacitors

Benzothiazole (Bz) molecules with excellent electrochemical stability and activity are favor of enhancing the capacitance performance of N-doped graphene (NG) by non-covalent functionalization. Herein, Bz molecules with different substituent groups (-ketone, -methoxy, -ketone and-methoxy) are used to functionalize NG nanosheets by a hydrothermal method and freeze-drying procedure. The surface chemistry and structure of as-prepared functionalized NG nanosheets are investigated through UV − vis, FTIR, SEM, AFM, XPS, TGA, XRD, Raman and BET. The electrochemical results of four functionalized NG nanosheets show that the substituent groups on Bz molecules have a great influence on their capacitive properties, among which the NG modified by the 6-methoxy benzothiazol-2-ketone (1-MhzNG) demonstrates the highest specific capacitance (420 F g −1 at 1 A g −1 ) and excellent cycle stability of 95.7 % after 10,000 cycles. In addition, the assembled supercapacitor based on the 1-MhzNG electrode delivers the highest energy density of 22.5 Wh kg −1 at 809 W kg −1 . Our work provides a new idea to modify graphene with novel organic small molecules for high-performance SCs.