The impact of carbon nanotubes on the optical, electrical, and magnetic parameters of Ni2+ and Co2+ based spinel ferrites

Surfactant-assisted co-precipitation method was used to synthesize Ni2+ and Co2+ based spinel ferrite nanoparticles. These ferrites are NiFe2O4, CoFe2O4, and Ni0.4Co0.6Fe2O4. The structural elucidation of the synthesized nanoparticles was carried by X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR). Both XRD and FTIR confirmed the spinel structure of prepared ferrite nanoparticles. The Debye-Scherrer equation showed the crystallite size in the range 6-15 nm. This range of particles size is an excellent range for a good signal to noise ratio. XRD result showed that the lattice constant value in Ni0.4Co0.6Fe2O4 decreased with increase in nickel ion concentration. FTIR revealed vibrational frequencies due to the presence of certain functional groups and octahedral and tetrahedral sites of ferrites nanoparticles. Nanocomposites of carbon nanotubes (CNTs) with spinel ferrite nanoparticles were prepared. CNTs influenced the various properties of spinel ferrite nanoparticles. The most affected properties are optical band gap, magnetic properties, dielectric properties, and photocatalytic applications. Ultraviolet-visible spectroscopy was used to study optical properties and photocatalysis. A Tauc plot showed a decrease in nanocomposite band gap values, due to the lower band gap of CNTs. Heterostructures of Ni0.4Co0.6Fe2O4 with carbon nanotubes showed enhanced magnetic behavior and low values of dielectric constant at high-frequency regions due to an increase in cobalt ion concentration. Photocatalytic activity was measured by the degradation of typical organic dye methylene blue (MB). UV-visible spectra of MB in presence of ferrite nanoparticles and their composites showed degradation of MB in visible light irradiation.