Enhanced Photocatalytic Decomposition Efficacy of Novel MgO NPs: Impact of Annealing Temperatures

The magnesium oxide (MgO) nanoparticles (NPs) were prepared using the sol–gel method and the prepared nanoparticles were annealed at different temperatures (500, 600, and 700 °C). The prepared nanoparticles were characterized using X-ray diffraction (XRD) for the structural analysis (Rietveld refinement), SEM for surface morphological analysis, and the energy dispersive X-ray analysis for elemental compositional analysis. The detailed structural analyses proved the expansion of the unit cell by increasing the annealing temperature. The detailed electronic bonding behavior and the expansion of the unit cell of the prepared nanoparticles were analyzed and reported using the maximum entropy method (MEM). The light absorption behavior of the MgO was probed using UV–Vis-NIR spectroscopic analysis. The photocatalytic decomposition capabilities of the synthesized MgO nanoparticles were studied against a model pollutant such as methylene blue dye. The maximum photocatalytic efficiency of 92% in 150 min was observed for MgO nanoparticles annealed at 700 °C.