Black pepper assisted sol-gel auto-combustion synthesis of yttrium doped cobalt ferrite and characterizations for enhancement of photocatalytic dye degradation efficiency

Yttrium doped cobalt ferrite nanoparticles (CoFe_2-xYₓO₄, x = 0.00, 0.01, 0.02, 0.03, 0.04, 0.05) were prepared by green synthesis approach. Piper nigrum (black pepper) was used as a biogenic fuel. TGA-DTA studies indicate that CoFe_2-xYₓO₄ nanoparticles were formed at 600 °C. The single phase cubic spinel structure was verified through X-ray diffraction analysis. The crystallite size obtained to be 23 nm - 15 nm. The lattice constant decreases with yttrium ion doping (x ≤ 0.05). The two absorption bands below 1000 cm⁻¹ were observed in FTIR spectra characterizes the spinel ferrite structure. FE-SEM images reflect spherical symmetry with grain sizes between 26 nm and 21 nm. The EDS analysis confirms the presence of all the elements in stoichiometric proportion. The elemental composition was further validated using XPS analysis. The Tauc plot suggest the increase in band gap values from 1.94 eV and 2.12 eV. The M-H curve exhibits the ferrimagnetic behaviour at 300 K. The blocking temperature suggest the superparamagnetic nature above 360 K from ZFC-FC curve. The MB dye degradation efficiency increases with increasing Y doping. The rate constant also increases with yttrium doping. The presence of H₂O₂ as an oxidizing agent in the solution increases the degradation efficiency as well as rate constant of the reaction.