Co0.5Ni0.5Fe2O4 nanoparticles were prepared by the plasma arc discharge method under arc currents of 200, 300, and 400 A in an air atmosphere. The XRD patterns reveal the formation of a single-phase cubic spinel. According to FESEM results, the average particle size in all powders is less than 100 nm. X-ray elemental mapping data confirms the homogeneous composition of the as-synthesized powders. The magnetic and optical data demonstrate a primarily soft ferromagnetic semiconductor behavior, characterized by a saturation magnetization ranging from 62 to 83 emu/g and a band gap energy between 1.86 and 2.15 eV. The photocatalytic activity of the powders synthesized using a 200 A arc, which possesses the lowest band gap energy of 1.86 eV, was assessed by conducting photodegradation experiments on the dyes congo red, methylene blue, and malachite green under UV irradiation in the presence and absence of H2O2. After 105 min of irradiation, the photocatalytic efficiencies of the powders without H2O2 were determined to be 29 %, 57 %, and 83 % for congo red, methylene blue, and malachite green dyes, respectively. However, in the presence of H2O2, the efficiencies significantly increase to 91 %, 95 %, and 96 % for the respective dyes.
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