A biomimetic Setaria viridis-inspired electrode with polyaniline nanowire arrays aligned on MoO3@polypyrrole core–shell nanobelts

Inspired by multi-scale structures mimicking Setaria viridis, herein, arrays of vertically aligned polyaniline (PANI) nanowires on MoO3/polypyrrole (PPy) core–shell nanobelts have been successfully synthesized via a two-step wet-chemistry strategy, including a simple in situ oxidative polymerization of pyrrole on MoO3 nanobelts, followed by an in situ oxidative polymerization of aniline on the MoO3/PPy core–shell nanobelts. By mimicking the hierarchically multi-scale topography of Setaria viridis for tailoring the nanostructures and functions of the electrode materials, in the resultant MoO3/PPy/PANI composites, the MoO3 nanobelt core acts as the “stalk” surrounded by conducting polymers, whereas the intermediate PPy functions as the buffer “grain” connecting the MoO3 and PANI nanowires, which provides good structural stability as well as an efficient electron transfer pathway. Moreover, the outermost PANI nanowire arrays act as the “bristles” allowing fast transport of ions and electrons between the electrodes. Due to their compositional and structural superiority, the as-obtained MoO3/PPy/PANI composites deliver excellent electrochemical energy storage performance including a high specific capacitance of 1315 F g−1 at 0.5 A g−1, a high energy density of 63 W h kg−1 and an excellent cycling stability (capacitance retention of 86% at 10 A g−1 after 20 000 cycles). The easy synthesis and excellent electrode performance of the MoO3/PPy/PANI composites make them attractive candidates as promising electrode materials for high-performance supercapacitors.