Co3O4 nanowires@MnO2 nanolayer or nanoflakes core–shell arrays for high-performance supercapacitors: The influence of morphology on performance

• MnO2 nanolayer is coated on Co3O4 nanowire arrays forming a core–shell nanocable structure via chemical bath deposition.
• The electrochemical performances of the MnO2 with two different morphologies are compared and investigated.
• Both the Co3O4 nanowires@MnO2 nanolayer and nanoflakes core–shell arrays possess high specific capacitance.

The Co3O4 nanowires@MnO2 nanolayer or nanoflakes core–shell arrays (Co3O4@MnO2 nanolayer or nanoflakes NWAs) supported on carbon fiber paper have been fabricated via a facile and green method and further investigated on the performance as the electrodes for supercapacitors. Our experimental results evidently indicate that both the Co3O4@MnO2 nanoflakes and nanolayer NWAs are capable of delivering specific capacitances as high as 1209.4 and 1215.6 F g−1 (based on the MnO2) at the current density of 1 A g−1. Due to the delicately designed hierarchical nanostructure that distributing the nanoscaled MnO2 on the nanowires with better electric conductivity, the active materials take advantage of the high effective surface area, facile electrolyte diffusion and fast electron transfer. The phenomenon that the Co3O4@MnO2 nanolayer NWAs with smaller specific surface area become superior in electrochemical performance to the Co3O4@MnO2 nanoflakes NWAs has been carefully investigated. The smaller charge transfer and electrolyte diffusion resistances are mainly demonstrated to be responsible. The analyses presented here could contribute to developing the optimal nanostructure of electrode materials for high-performance supercapacitors.