Sol–gel synthesized MgO nanoparticles: Versatile applications in photocatalytic dye degradation, heavy metal removal, CO 2 conversion, hydrogen production, and photoelectrochemical performance

Abstract This study investigates the synthesis and applications of magnesium oxide nanoparticles (MgO NPs) using the sol–gel method. X‐ray diffraction (XRD) confirmed a cubic crystalline structure with an average crystallite size of 22.53 ± 3.42 nm. Scanning electron microscopy (SEM) showed spherical nanoparticles with sizes ranging from 40 to 60 nm, with a mean diameter of 56.52 nm. Optical analysis showed a direct bandgap of 3.12 eV and a UV absorption peak at 308 nm. Fluorescence spectra revealed emission peaks at 408, 445, and 478 nm, attributed to oxygen vacancies. The MgO NPs demonstrated excellent photocatalytic activity, degrading 99.82% of Malachite Green dye in 120 min under sunlight (k = 0.02763 min −1 ). They also removed 98.75% of cadmium ions in 120 min (k = 0.01695 min −1 ) and exhibited stable adsorption for copper and lead over five cycles. In CO 2 conversion, the NPs produced 63 μmol/g methane and 58 μmol/g hydrogen in 4 h, with a hydrogen production rate of 1034 μmol·g −1 ·h −1 . Photoelectrochemical tests showed stable photocurrent response. These findings highlight MgO NPs' potential for wastewater treatment, heavy metal removal, CO 2 conversion, and hydrogen production, demonstrating their high effectiveness for environmental and energy applications.

• magnesium oxide nanoparticles
• sol-gel synthesis
• photocatalytic dye degradation
• malachite green
• heavy metal removal
• cadmium adsorption
• CO2 conversion
• methane production
• hydrogen production
• photoelectrochemical performance
• oxygen vacancies
• wastewater treatment
• solar photocatalysis

• 12 — Consommation et production responsables
• 6 — Eau propre et assainissement

• Advanced Photocatalysis Techniques
• Magnesium Oxide Properties and Applications
• Chemical and Physical Properties of Materials
• magnesium oxide nanoparticles
• sol-gel synthesis
• photocatalytic dye degradation
• malachite green
• heavy metal removal
• cadmium adsorption
• CO2 conversion
• methane production
• Renewable Energy, Sustainability and the Environment
• Materials Chemistry
• Energy
• Materials Science