Hierarchical Co3O4@PPy@MnO2 core–shell–shell nanowire arrays for enhanced electrochemical energy storage

Abstract Combining hydrothermal synthesis, electrodeposition with soaking process, we synthesized coaxial nanowire arrays consisting of Co 3 O 4 nanowire as the core, polypyrrole (PPy) as the inner shell and MnO 2 outer layer as the exodermis. The key to fabricate one-dimensional hierarchical architecture, Co 3 O 4 @PPy@MnO 2 “core–shell–shell” nanowires, was to introduce a PPy intermediate layer on the surface of Co 3 O 4 nanowire, which could enhance the conductivity of nanowire arrays and act as a reactive template to induce a coating of amorphous MnO 2 . The device based on the ternary composite Co 3 O 4 @PPy@MnO 2 nanowire arrays exhibited prominent electrochemical performance with a high energy density of 34.3 Wh kg −1 at a power density of 80.0 W kg −1 and a remarkable long-term cycling stability. In addition, the performance of as-assembled asymmetrical supercapacitor was demonstrated using a DC motor. The results imply that ternary composite based electrode materials have enormous potential for energy storage devices and systems.