Flexible Fe-Doped NiO/Ni-Foam Substrate Nano-System Based Electrode with Tunable Opto-Electrochemical Attributes for Supercapacitor Applications

This work underlines the modification and effect of iron doping on different characteristics of NiO nanoparticles. The facile hydrothermal method was followed to form pristine and iron doped (4% and 8%) NiO sample. The X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), transmission electron microscopy (TEM), UV–Vis spectroscopy and Raman spectroscopy techniques were employed for the identification of phase, morphology, microstructural details and optical property of the as synthesized Fe doped NiO samples. XRD measurements of the as synthesized Fe doped NiO samples revealed the polycrystalline nature with the crystallite size varying from 11 nm–20 nm showing hexagonal structure. Surface morphology investigation carried out by using SEM showed the varied morphology of as synthesized samples. UV–vis investigation revealed a red shift with increasing iron doping content, which corresponds to a decrease in optical bandgap values from 3.4 eV for pure NiO to 2.2 eV for 8% Fe doped NiO sample thus giving a wide tuneable absorption bandgap. The study of cyclovoltammetry and PEIS demonstrates the novelty of this work showing exceptionally high electrochemical performance in a three-electrode system with highest specific capacitance of 977 F g −1 at scan rate of 20 mV sec −1 for 8% doped sample.Vibrating sample magnetometry (VSM) measurement shows good ferromagnetic behaviour with high coercivity for iron doped NiO sample making it a useful MRI agent. The results demonstrate as synthesised iron doped NiO nanoparticles as viable material for supercapacitor applications.