Eco‐Friendly Synthesis of Zinc Oxide and Magnesium Oxide Nanoparticles: Comparative Insights into Characterization, Electrochemical, and Photocatalytic Properties

ABSTRACT In this study, zinc oxide nanoparticles (ZnONPs) and magnesium oxide nanoparticles (MgONPs) were successfully synthesized via green sol–gel method employing Curcuma longa extract as a stabilizing agent. The characteristics of the materials were examined using X‐ray diffraction, scanning electron microscopy, field‐emission scanning electron microscopy, energy‐dispersive X‐ray spectroscopy, ultraviolet–visible diffuse reflectance spectroscopy, cyclic voltammetry, and electrochemical impedance spectroscopy. On the other hand, the optical band gap energies were determined to be 3.20 eV for ZnONPs and 4.80 eV for MgONPs, which is based on the calculated conduction band and valence band positions, and a photocatalytic mechanism involving the generation of reactive oxygen species was also proposed. Specifically, the photocatalytic activity was evaluated through the degradation of a methylene blue solution under visible‐light irradiation. The results revealed that MgONPs exhibit a photocatalytic degradation efficiency toward methylene blue approximately 100%, which was significantly higher than that of ZnONPs (89%) under similar conditions. These findings highlight the superior photocatalytic capability of MgONPs and suggest their strong potential for environmentally friendly water treatment applications, particularly in the removal of organic pollutants using sustainable and green photocatalytic materials.