MgO nanostructures: Synthesis, characterization and tentative mechanisms of nanoparticles formation

Abstract

Magnesium oxide nanostructures (MgO-NSs) were synthesized using various solvents to obtain nanoparticles (MgO-NPs) and using a surfactant (CTAB) for the mesoporous-assembled structure. The MgO-NSs were characterized using infra-red and diffuse reflectance UV–Vis spectroscopies, X-ray diffraction (XRD) and electron microscopy. The MgO-NPs obtained were found to have different morphologies and all were nano-sized (<100 nm). Energy gap values for the MgO-NSs also differed, with values for the NPs of 6.25 eV (water), 6.5 eV (ethanol), 6.53 eV (acetic acid) and 5.85 eV (ethylene glycol), with the mesoporous sample registering 6.24 eV. The latter presented a mid-gap value of ∼ 5.5 eV that could be associated to energetic states located inside the band gap generated by surface O2− ions, with differing coordinations, and/or by defects in the surface. The diffuse reflectance spectra reiterated these results. Considering the nature of the synthesis process, some basic aspects of the mechanism of formation of the MgO-NPs were indicated.