A comprehensive analysis of the impact of annealing temperature variation on the structural, optical, morphological, magnetic, and photocatalytic properties of CoFe2O4 nanoparticles

Spinel cobalt ferrite (CoFe₂O₄) nanoparticles have garnered significant interest due to their versatile properties and potential applications. Among the various factors influencing their properties, annealing temperature stands out as a crucial parameter. In this comprehensive analysis, we studied the effects of various annealing temperatures (400, 500, 600, and 700 °C) on the structural, optical, morphological, magnetic, and photocatalytic characteristics of CoFe₂O₄ nanoparticles. X-ray powder diffraction (XRD) studies reveal the crystalline structure of CoFe₂O₄ nanoparticles. The crystallite size was increased from 13.544 nm to 20.312 nm with the increasing annealing temperature from 400 to 700 °C. The effect of annealing temperature on cationic-anionic interaction of the nanomaterials is studied through Fourier transform infrared spectroscopy (FTIR). Morphological and elemental composition of the nanomaterials is evaluated through Field Effect Scanning electron microscopy (FESEM) and energy dispersive spectroscopy (EDS). Changes in annealing temperature lead to variations in particle size, morphology, and surface area, influencing their catalytic activity. UV–visible spectroscopy (UV–Vis) and photoluminiscene spectroscopy (PL) were employed to investigate the optical properties of CoFe₂O₄ nanoparticles. Annealing temperature variation influences the band gap energy, affecting the absorption and emission properties of the nanoparticles. Tauc’s plot was employed to obtain the band gap of the nanomaterials. The band gap was decreased from 2.33 eV to 1.92 eV with rise in annealing temperature. An emission peak at 465.80 nm was observed through PL spectroscopy. The magnetic properties of CoFe₂O₄ nanoparticles, including saturation magnetization and coercivity, are examined using a vibrating sample magnetometer (VSM). The sample annealed at 400 °C has shown highest magnetic parameters with saturation magnetization, coercivity, and remanent magnetization of 51.53 emu/g, 1860 Oe, and 17.5 emu/g respectively. Annealing temperature variation alters the magnetic behavior, affecting the nanoparticles' utility in magnetic and photocatalytic applications. The photocatalytic performance of CoFe₂O₄ nanoparticles is examined through degradation of methylene blue dye under UV–Visible irradiation. The sample annealed at 400 °C exhibited the highest photocatalytic efficiency, achieving 74.46% discoloration. The involvement of hydroxyl ion (OH⁻) and singlet oxygen ion (O₂⁻) was verified through a Scavenger test using Isopropyl Alcohol (IPA) and Disodium Ethylenediaminetetraacetic Acid (EDTA 2NA), respectively. The kinetics of dye removal was analyzed using various rate models. Additionally, the material's stability was evaluated by calculating its recycling efficiency over four successive cycles.