Tobacco mosaic virus-templated hierarchical Ni/NiO with high electrochemical charge storage performances

Abstract

Three-dimesional hierarchical electrodes exhibiting multi-dimensional geometries provide exceptional advantages for advanced energy storage performance. In this work, we report the fabrication and characterization of biotemplated hierarchical-Ni/NiO electrodes enabled by thermal oxidation of electroless Ni-coated Tobacco mosaic viruses (TMVs) self-assembled on Au-coated Si micropillar arrays. Uniform NiO formation on the metallized TMV nanoscaffolds is characterized by XPS and STEM-EELS analysis and the electrochemical performance was characterized in 2M KOH solution. The hierarchical-Ni/NiO show a 3.3 and 32.6 times increase in areal capacity (81.4μAhcm−2) compared to solely nanostructured (24.3μAhcm−2) and planar electrodes (2.5μAhcm−2), respectively. The NiO electrodes show interesting capacity increase phenomenon during the initial activation cycles. Based on our experimental analysis, it is attributed to both an increase in active surface area/mesoporosity and NiO content during the initial charge/discharge cycles, and the increase has dependence on electrode geometry. The hierarhical-Ni/NiO electrode exhibit excellent cycle stability up to 1500 charge/discharge cycles at 2mAcm−2 with no capacity fading. Based on the results, the hierarchical-Ni/NiO is a promising candidate for advanced electrochemical energy storage devices.