Tailoring ZnO Nanoparticles with Mg Doping: Structural, Optical BandGap and Morphological Insights for Industrial Dye Degradation Applications

Magnesium-doped zinc oxide (Mg:ZnO) nanoparticles were synthesized via a chemical co-precipitation technique to systematically investigate the effects of Mg incorporation on the structural, optical, and morphological properties of ZnO. The doping levels of Mg were varied (0.1 and 0.3 wt.%) to elucidate compositional influence on the host lattice. X-ray diffraction (XRD) analysis confirmed that all synthesized nanoparticles crystallize in the hexagonal wurtzite phase with no secondary phases detected, indicating the successful substitution of Mg²⁺ ions into the Zn²⁺ sites of the ZnO lattice. A notable shift in peak positions and changes in lattice parameters were observed with increasing Mg content, attributed to lattice contraction due to the smaller ionic radius of Mg²⁺. Morphological assessment via scanning electron microscopy (SEM) revealed nanoscale particles exhibiting morphology evolution with Mg concentration, transitioning from nest-like to flower-like and cauliflower-like nanostructures. Elemental composition confirmed by energy-dispersive X-ray spectroscopy (EDX) validated the presence and uniform distribution of Mg in the ZnO matrix. UV–Vis–NIR spectroscopic analysis demonstrated a distinct blue shift in the absorption edge with increased Mg doping, accompanied by a bandgap widening from 3.16 eV (pure ZnO) to 3.62 eV (0.3 wt.% Mg:ZnO), attributed to the Burstein–Moss effect. These findings substantiate that Mg doping effectively tailors the band structure, defect states, and morphological features of ZnO nanoparticles, enhancing their potential for industrial pollutant dye degradation applications.