Effect of Cu²⁺ Ions Substitution on Structure and Photocatalytic Activity of Cu_xNi_1−xFe₂O₄ Nanoparticles

Photocatalytic degradation is a promising emerging method for eliminating dye from contaminated water. The core of photocatalytic degradation lies in the design and preparation of high-performance catalysts that do not produce polluting secondary products. Here, we explore magnetic NiFe₂O₄ materials doped with varying amounts of Cu²⁺ ions (Cu_xNi_1−xFe₂O₄, where x = 0–0.5) via the combustion method to target rhodamine B (RhB) dye removal. To validate whether Cu²⁺ is incorporated, the structural characteristics of the catalysts were analyzed using physical techniques. The photocatalytic activity of Cu_xNi_1−xFe₂O₄ (x = 0–0.5) was evaluated based on the degradation of RhB, achieving 97.25% degradation efficiency under optimized conditions. The radical quenching results revealed that ^•OH played a pivotal factor in the photodegradation process. Additionally, chemical oxygen demand (COD) testing yielded a level of 24.67 mg L⁻¹, significantly lower than the World Health Organization (WHO) drinking water standards. Overall, our findings reached high photocatalytic activity of Cu_0.5Ni_0.5Fe₂O₄ in removing a harmful dye (RhB) from water.