In recent years, special attention of energy researchers has been paid to application of polymer–carbon dots composite in energy storage systems. In this work, for the first time, we introduced a combination of polyaniline, carbon dots, polypyrrole and graphene as high performance supercapacitor. Synergistic effect of conductive polymers combined with specific properties of graphene and carbon dots improved the electrochemical performance of supercapacitor. Carbon dots was prepared from carrot juice hydrothermally as a biomass carbon source and polyaniline–carbon dots was synthesized via in-situ polymerization. Electrochemical performance of polyaniline with different carbon dots content was investigated and nanocomposite of polyaniline with 10 wt% carbon dots was selected to mix with polypyrrole–graphene to obtain a high potential window supercapacitor. The as-prepared composite was characterized by several spectroscopic and microscopic techniques. The electrochemical properties of this electrode were studied by cyclic voltammetry, galvanostatic charge/discharge, and electrochemical impedance spectroscopy techniques. A polyaniline–carbon dots (10%)/polypyrrole–graphene has showed the maximum specific capacitance of 396 F g− 1. Value of specific capacity remained at 62% under the current density of 5 A g− 1.

    Abstract
    1 Introduction
    2 Experimental
        2.1 Material
        2.2 Preparation of carrot derived carbon dots (CDs)
        2.3 Preparation of polyaniline–carrot derived carbon dots (PC)
        2.4 Preparation of polypyrrole–graphene (PG)
        2.5 Preparation of polyaniline–carrot derived carbon dotspolypyrrole–graphene (PCPG)
        2.6 Electrochemical measurements
    3 Results and discussion
        3.1 Electrochemical evaluations
    4 Conclusions
    Acknowledgements 
    References

• Ghasem Oskueyan(Polymer Chemistry Laboratory, Department of Organic Chemistry, Faculty of Chemistry, University of Mazandaran, Faculty of Chemistry and Chemical Engineering, Malek-Ashtar University of Technology)
• Moslem Mansour Lakouraj(Polymer Chemistry Laboratory, Department of Organic Chemistry, Faculty of Chemistry, University of Mazandaran)
• Mojtaba Mahyari(Faculty of Chemistry and Chemical Engineering, Malek-Ashtar University of Technology)