Construction of polypyrrole-wrapped hierarchical CoMoO4 nanotubes as a high-performance electrode for supercapacitors

Abstract For the creation of advanced electrochemical energy storage devices, a large challenge still remains in the designing and engineering of active electrodes with tailored nanoarchitectures and components that provide optimized electrochemical performances. In this study, CoMoO4@polypyrrole nano-heterostructures (NHs) are constructed by wrapping a polypyrrole (PPy) shell around the surface of CoMoO4 nanotubes (NTs) using a self-templated reaction and a subsequent in situ gas-phase polymerization reaction. CoMoO4 NTs possess a large amount of electroactive sites, short ion diffusion pathways, and provide sufficient buffering space. The PPy shell, on the other hand, is conductive, thereby allowing for efficient electron transport and fast charge transfer kinetics. By using their respective advantageous qualities for energy storage, along with the synergistic effect between the CoMoO4 NTs and PPy shell, the CoMoO4@PPy NHs electrode demonstrated improved specific capacitances of 1203 F g−1 at 2 A g−1 and 974 F g−1 at 20 A g−1, as well as 96% capacitance retention after 5000 cycles at 10 A g−1. Furthermore, asymmetric supercapacitor (ASC) fabricated using the CoMoO4@PPy//N-doped carbon NTs (N-CNTs) provided an energy density of 40.3 Wh kg−1 at a power density of 749 W kg−1. These results suggest the considerable potential of CoMoO4@PPy NHs for use in high-performance energy-storage devices.