Role of composition in photocatalytic efficiency of Cu2+ and Al3+ Co-doped Ni–Zn ferrites nanoparticles

Ni_0.5Zn_0.5-xCu_xAl_yFe_2-yO₄ nanoparticles x = y= (0.0, 0.1, 0.2 and 0.3) wt.% were formed by implementing self-propagating auto-combustion technic. The structure, morphology, magnetic, optical, and photocatalytic properties of the developed nanocomposite were evaluated. XRD samples' examination confirmed cubic spinel phase presence. Also, the structure's crystallite sizes were diminished from 35.11 to 29.25 nm as Cu²⁺ and Al³⁺ ions concentrations were increased. FTIR spectra revealed characteristic metal–oxygen stretching bands near 565–568 cm⁻¹, while FE-SEM and HR-TEM analyses showed nanocrystalline, cubic morphologies with increasing surface irregularity at higher dopant levels. VSM results demonstrated composition-dependent magnetic behavior, with saturation magnetization (M_s) magnitudes ranging from 41.50 to 48.77 emu/g. UV–Vis optical analysis revealed an increasing direct band gap energy from 1.11 to 1.18 eV. The efficiency of methylene blue photocatalytic degradation process by visible light irradiation was improved as the dopants contents were increased. This degradation had reached a maximum of 35.1 % after 120 min of interaction with the Ni_0.5Zn_0.5-xCu_xAl_yFe_2-yO₄ nanocomposite. Density Functional Theory (DFT) and Fukui function analysis identified key reactive oxygen sites and confirmed the favorable electronic structure for photocatalysis. These findings validate the engineered ferrites as effective, tunable photocatalyst for dye degradation and environmental remediation.