Biotemplated hierarchical nickel oxide supercapacitor electrodes

This paper presents fabrication and characterization of Tobacco mosaic virus (TMV)-templated hierarchical nickel oxide (NiO) supercapacitor electrodes. The hierarchical NiO electrode was created by integrating silicon (Si) micropillars with thermally oxidized nickel (Ni)-coated TMVs. SEM images taken after the high temperature oxidation process verified the robustness of the bio-nanotemplates, while the formation of Ni(core)/NiO(shell) structure around the rod-like virus was confirmed by scanning transmission electron microscopy (STEM). Electrochemical characterization showed that the capacitance for TMV structured Ni/NiO electrodes continuously increases for the first 500 cycles, with significantly higher, non-linear increase for the hierarchical versus TMV-only (nanostructured) electrodes. Further electrochemical and SEM analysis support the hypothesis that the capacity increase is due to the increase in electroactive sites of the nanostructured NiO throughout the initial charge/discharge cycles.