Hierarchical Co 3 O 4 @PPy core-shell composite nanowires for supercapacitors with enhanced electrochemical performance

Abstract Hierarchical Co 3 O 4 @ polypyrrole (PPy) core-shell composite nanowires (NWs) were successfully fabricated by a template-free hydrothermal route combined with in-situ chemical polymerization. Based on the composition and morphology characterization, it is found that the well-aligned Co 3 O 4 nanowires were uniformly coated with a thin layer of amorphous PPy. When directly used as an electrode material for supercapacitors, the Co 3 O 4 @PPy nanowire arrays exhibited high specific capacitance of 2122 F g −1 (3.18 Fcm −2 ) at 5 mA cm −2 , which is much higher than that of the pristine Co 3 O 4 nanowire arrays and improved cycling stability with 77.8% capacitance retention over 5000 cycles at 25 mA cm −2 . The highly electronic conductive and electroactive PPy layer could significantly reduce charge transfer resistance and increase active sites. This synergistic strategy of the arrays structure and the PPy buffer layer can provide simple, efficient and versatile blue-prints for fabrication of Co 3 O 4 -based nanocomposites for extending its application for electrochemical energy storage.