Synthesis, multifunctional properties, and photocatalysis of cobalt ferrite (CoFe₂O₄) nanoparticles

This study focuses on synthesizing cobalt ferrite (CoFe₂O₄) nanoparticles via a sol-gel method using ethylene glycol (EG) and polyethylene glycol (PEG) as capping and stabilizing agents, and examines their effects on structural, optical, magnetic, dielectric, and photocatalytic properties. Various characterization techniques, including X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), and UV-Vis diffuse reflectance spectroscopy (DRS), were used to investigate the incorporation of CoFe₂O₄ and the stabilizers. Both EG- and PEG-capped nanoparticles exhibited a cubic spinel structure. PEG enhanced crystallinity and dispersion, whereas EG facilitated nucleation, yielding smaller, more agglomerated particles. Magnetic measurements revealed that PEG-capped nanoparticles had a higher saturation magnetization (70.1 emu·g⁻¹), whereas the EG-capped nanoparticles demonstrated greater coercivity (about 550 G). Dielectric studies indicated that PEG-derived samples exhibited higher permittivity and alternating current (AC) conductivity. In the photocatalytic degradation of Rhodamine B under UV light, EG-derived nanoparticles achieved 95.8% degradation in 115 min, while PEG-derived nanoparticles reached 96.2% degradation in 150 min. This study provides a clear comparative understanding of how the molecular weight and chain length of polyol stabilizers (EG and PEG) influence the structure-property relationships in CoFe₂O₄ nanoparticles.