This investigation reported a one-step green synthesis of nickel oxide nanoparticles (NiO NPs) using aloe vera leaves extract solution for their application in a supercapacitor. This method used aloe vera leaves as a reducing agent, which is very simple and cost-effective. The synthesized NPs were thoroughly characterized using various techniques. The X-ray diffraction analysis unequivocally confirmed the crystalline nature; field emission scanning electron microscopy and transmission electron microscopy images showed different shapes and forms of an agglomerated cluster of synthesized NPs. The absorption spectra were recorded from UV visible spectroscopy, while Fourier transform infrared spectroscopy provided insights into the functional groups present. Electrochemical assessments were carried out via cyclic voltammetry, galvanostatic charging-discharging and electrochemical impedance spectroscopy. These experiments were performed using a 2 M KOH electrolyte within a 1.0 V potential window. Impressively, the single electrode displayed a remarkable specific capacitance of 462 F g⁻¹ at a scan rate of 1 mV s⁻¹ and 336 F g⁻¹ at a current density of 0.76 A g⁻¹. Further, a symmetric two-electrode device (NiO||NiO) has been successfully fabricated by employing a separator between the electrodes. The device exhibited an exceptional specific capacitance of approximately 239 F g⁻¹, along with an energy density of 47.8 Wh kg⁻¹ and a power density of 545 W kg⁻¹ at 1 A g⁻¹ current density within a 1.2 V potential window. The fabricated device also shows a retention capacity of 89% at 10 A g⁻¹ after 2000 cycles with 114% of columbic efficiency. The present study underscores the effectiveness of the green synthesis approach in producing NiO NPs and establishes their potential as highly promising candidates for supercapacitor applications, showcasing both excellent electrochemical performance in a three-electrode system and remarkable stability in a practical two-electrode device. The results collectively highlight the efficacy of the green approach in producing NiO NPs, establishing its potential as a highly promising candidate for supercapacitor application.

MnO₂ is the most favorable material in power storage due to its technological significance and potential applications in pseudocapacitance (due to various oxidative states allowing efficient charge transfer to meet energy demands), where its properties are considerably influenced by its structure and surface morphology. In the present study, a facile hydrothermal route was used to produce different phases of MnO₂ (α, β, and γ) with different morphologies. The electrochemical performance of the synthesized phases was studied in aqueous sodium sulfate as an electrolyte. X-ray diffraction, UV–Vis spectroscopy, and Fourier-transform infrared spectroscopy were used to characterize the synthesized material. The surface morphology and topography were examined using field-emission scanning electron microscopy. The direct band gap of α-, β-, and γ-MnO₂ was found to be 1.86 eV, 1.08 eV, and 1.68 eV, lying in the semiconducting range, further enhancing the electrochemical performance. It was found that α-MnO₂ had a maximum specific capacitance of 138 F/g at 1 A/g, and the symmetric device fabricated using α-MnO₂ had a specific capacitance of 86 F/g at 1 A/g.

Multifunctional magnetic composite nanoparticles (NPs) with antibiotics have demonstrated symbiotic effects because of their promising antimicrobial properties. The antimicrobial agent reduces side effects and dosage, and increases drug delivery efficiency. In this study, SiO₂ coated over Fe₃O₄ magnetic nanoparticles (MNPs) were prepared by a solvothermal method. The MNPs were characterized by using X-ray diffraction (XRD), transmission electron microscopy (TEM), ultraviolet-visible spectroscopy (UV-vis), and Fourier transform infrared spectroscopy (FTIR). The antimicrobial tests were carried out using the disk diffusion method. The electrochemical sensing was investigated by cyclic voltammetry with varying As(III) concentrations from 1–10 ppb. The microstructural results showed the formation of spherical-shaped Fe₃O₄@SiO₂ MNPs with 15–30 nm diameters. UV-vis results showed that Fe₃O₄ NPs promote visible light absorption of Fe₃O₄@SiO₂ MNPs because of well-structured and unvarying shell thickness which is beneficial for the absorption of organic dyes. With an increase in the concentration of As(III), there was a shift in potential and an increase in oxidation peak current, showing the electrocatalytic capacity of the modified electrode. The SiO₂ deposited on Fe₃O₄ displayed an admirable microbial operation. These Fe₃O₄@SiO₂ MNPs are easily absorbed by cells and have the potential to influence bacterial cells both within and outside of the cell membrane, making them an intriguing candidate for use in a variety of biological applications in the future.