Cobalt ferrite (CoFe2O4) is an interesting material due to its rich physical properties. In order
to study the influence of synthetic methods on the crystalline and morphological structure, optical and
magnetic properties of the CoFe2O4, we synthesized here the CoFe2O4 by three different methods,
including the chemical co-precipitation method, sol-gel method, and ceramic method. The resulting
powders were characterized by different analyses: XRD, SEM, TEM, BET, FTIR, UV-Vis, PL, XPS,
and surface acidity. The characterization results showed a significant variation in the structural, particle
size, surface area, and optical properties of pure cobalt ferrite with changing the synthetic method. Both
XRD and FTIR analyses confirm the formation of the cubic spinel phase, where the crystallite size
changes from 21 to 36 nm. XPS analyses demonstrated the effect of the synthetic method on the cation
distribution at the tetrahedral and octahedral sites in the spinel ferrite lattice. The magnetic properties
of the prepared samples were studied at room temperature using the vibrating sample magnetometer
(VSM) and found to be strongly dependent on the synthetic method and showed either ferromagnetic
or super-paramagnetic character. The cobalt ferrite samples showed high photocatalytic activity against
Basic Red 18 (BR 18) dye under visible light irradiation. The effects of particle size, surface areas, and
morphology on the photocatalytic activity were discussed and the positive holes are suggested to be the
major active species of the dye dissociation.