Improved electrochemical performance of the iron-doped NiO nanoparticles at varying calcination temperatures and examination of their supercapacitor applications

The scientific community is interested in increasing oxide electrochemical characteristics for supercapacitor applications. The present research explores the development of supercapacitor electrodes using Fe-doped NiO nanoparticles synthesised via chemical co-precipitation method with varied calcination temperatures (350, 550, and 750 °C). The key innovation of the work lies in the systematic investigation of the effects of calcination temperature on the electrochemical properties and structural characteristics of the Fe-doped NiO nanoparticles. X-ray diffraction (XRD) analysis revealed a trend of increasing crystallite size with rising temperatures, and optical studies indicated a decreasing trend in the energy band gap from 3.67 eV to 3.23 eV. Fourier transform infrared (FTIR) spectroscopy confirmed the metal-oxygen bond in the molecules. Scanning electron microscopy (SEM) and High-Resolution Transmission Electron Microscopy (HR-TEM) analysis showed the mesoporous spherical morphology of the nanoparticles. Energy-dispersive X-ray spectroscopy (EDX) ensured the samples' elemental composition purity. Brunauer–Emmett–Teller (BET) shows a specific surface area of around 180.8 m²/g was obtained for Fe-doped NiO nanoparticles at 350 °C. Electrochemical tests demonstrated that the Fe-doped NiO electrodes, especially calcined at 350 °C, exhibit superior specific capacitance values (635 F/g) and impressive cycle stability with 93.29 % capacitance retention after 5000 cycles. The present demonstrates the potential of optimizing calcination temperatures to enhance the electrochemical performance and stability of Fe-doped NiO supercapacitor electrodes, marking a significant advancement in supercapacitor technology.