Bioengineered Nickel Oxide Nanofabrication for Energy Storage Systems, Degradation of Refractory Water Toxicity, and Antibacterial Study

Abstract Nickel oxide (NiO) nanoparticles were synthesized using a green method involving Pterolobium hexapetalum flower extract as the reducing agent. Synthesized nickel oxide nanoparticles (NiO NPs) were thoroughly characterized using X‐ray diffraction, UV–vis spectroscopy, Fourier‐transform infrared spectroscopy, transmission electron microscopy (TEM), scanning electron microscopy (SEM), and Brunauer–Emmett–Teller (BET) surface area analysis. The XRD analysis confirmed the pure formation of NiO NPs. TEM and SEM images revealed the size, shape, and surface morphology of the nanoparticles. BET analysis indicated a high surface area, making these nanoparticles suitable for various applications. The NiO NPs were further investigated for their potential in supercapacitor applications, demonstrating excellent electrochemical performance. NiO@rGO electrode with graphene proportion showed a maximum specific capacity of 1266 Fg −1 at 1 Ag −1 . Moreover, following the 3000‐cycle assessment, the specific retention of 98.2% confirmed that the electrode had high cyclic stability. Additionally, their effectiveness in dye degradation was evaluated, showing promising results in removing organic dyes from wastewater. The antibacterial activity of the NiO nanoparticles was also assessed, indicating significant inhibition against various bacterial strains. These multifaceted studies suggest that NiO NPs synthesized from plant extract hold great promise for applications in energy storage, environmental remediation, and antimicrobial treatments.