▎ 摘　　要

In this paper, a new class of sandwich-like ternary hierarchical nanosheets is fabricated by a facile, reproducible, and scalable two-step strategy. Conducting polymer polyaniline (PANI) is coated on reduced graphene oxide (RGO) to form PANI/RGO hybrid nanosheets. Then, nanoflaky manganese dioxide (MnO2) in situ grows on PANI/RGO hybrid nanosheets to obtain ternary hierarchical nanosheets MnO2/PANI/RGO by simply mixing PANI/RGO and KMnO4 under mild condition. The electrochemical behavior shows that MnO2/PANI/RGO electrode material is a typical pseudo-capacitance. In comparison with RGO, PANI, and PANI/RGO hybrid nanosheets, MnO2/PANI/RGO composites display the highest specific capacitance of 1090.2 F g(-1) at 0.5 A g(-1) in three-electrode configuration. They maintain 82.3% initial capacitance after 5000 consecutive cycles at 0.5 A g(-1). The excellent electrochemical performance is attributed to nanometer-sized flaky MnO2 in situ growth on the surface of PANI/RGO, which can enhance electrode/electrolyte interface areas, provide high electroactive regions and short diffusion lengths, and protect the structure of composites effectively. Thus, the sandwich-like ternary hierarchical nanosheets of MnO2/PANI/RGO are excellent electrode material in supercapacitor with high specific capacitance and the long-term cycle stability, which is helpful in developing new kinds of portable energy storage devices. (C) 2016 Elsevier B.V. All rights reserved.