Studies on photoluminescence, electrochemical sensors, and photocatalysis using Ho³⁺-doped MgAl₂O₄ nanophosphors

Ho³⁺-doped MgAl₂O₄ nanophosphors (1–11 mol%) were synthesized via solution combustion method and oxalyldihydrazide used as fuel. The findings revealed a range of band gap energies between 4.86 and 5.42 eV. Ho³⁺ ions in the host undergo f-f transitions that are triggered at 406 nm, and as a result, exhibit discrete photoluminescence emission peaks between 406 and 605 nm. Enhanced MgAl₂O₄ has chromaticity diagram (CIE) coordinates from orange–red to yellow region and 97% color purity. Photocatalytic properties of NPs under UV light led to the discovery that a rapid orange–red dye is activated at 493 nm. Fast orange–red dye removal using the new photocatalysts and MgAl₂O₄:Ho³⁺ nanophosphors has been demonstrated. The investigation showed that 89.02% of the dye lost its color after being exposed to radiation for 120 min. The cyclic voltametric method can detect lead pollution using the modified MgAl₂O₄:Ho³⁺ carbon paste electrode. Based on their electrochemical performance, we conclude that MgAl₂O₄:Ho³⁺ nanophosphors are effective lead detecting electrode materials.