Enhanced Luminescence and Photocatalytic Activity of the Monovalent Sodium (Na + ) Co-Doped MgAl 2 O 4 : Eu 3+ Nanostructures

In the present work, monovalent sodium (Na⁺) co-doped MgAl₂O₄: Eu³⁺ photocatalyst was prepared bya combustion method followed by annealing at 1000 °. The doping of trivalent Eu³⁺ ions into a host MgAl₂O₄ with divalent cations leads to luminescence quenching and hence needs charge compensation to control the quenching, which was systematically studied by powder X-ray diffraction (PXRD), diffuse reflectance spectroscopy (DRS), photoluminescence (PL) and X-ray photoelectron spectroscopy (XPS) etc. The PL spectra of doped and co-doped samples exhibit sharp peaks around 580, 592, 611, 628 and 692 nm associated to the ⁵D₀ → ⁷ F_j (j = 1–4) transitions of the Eu³⁺ ions, respectively. The interplay of Na⁺ and Eu³⁺ ions in the host MgAl₂O₄ lattice appears to be an effective charge compensation mechanism that achieve better crystal quality and enhanced red luminescence of such co-doped particles. In addition, we studied the photocatalytic activity of all the prepared photocatalysts. Specifically, Na⁺ co-doped MgAl₂O₄: Eu³⁺ photocatalyst revealed the enhanced photocatalytic activity with photodegradation efficiency 82% under visible light irradiation.