Magnetic and photocatalytic properties of CoFe2O4/Ni nanocomposites

In this research, hard/soft CoFe₂O₄/Ni magnetic nanocomposite samples with different concentrations of Ni were successfully produced by a two-step mechanical alloying route. Single-phase CoFe₂O₄ (CFO), having the average particle size of 35 nm, saturation magnetization of 71 emu/g, and bandgap energy of 2.6 eV was synthesized via the mechanical alloying method. A mixture of as-synthesized CFO and 10, 30 and, 50 wt. % Ni powder has been severely milled to prepare magnetic nanocomposite samples. The effects of different Ni content on the characteristics of the nanocomposite samples have been investigated. FESEM images showed that the ductile nickel powder particles get flattened after 1 h milling, whereas the brittle CFO particles get fragmented by increasing milling time to 10 h. The single-phase-like hysteresis loop, and the switching field distribution curves alongside the simultaneous enhancements of maximum energy product and remanence reflect the presence of exchange spring phenomenon in the nanocomposite samples. Also, the diffuse reflectance spectroscopy (DRS) analysis evidence the reduction of bandgap energy for 10 wt.% Ni containing nanocomposite sample from 2.44 to 2.15 eV on increasing the milling time from 1 to 10 h. Under the optimum photocatalyst operating conditions, the CFO/10 wt% Ni sample exhibited the highest photocatalytic activity of 93.6% for methylene blue (MB) degradation in comparison with the cobalt ferrite sample. Eventually, the detailed kinetic and mechanism to describe the improvement of the photocatalytic performance were suggested.

Graphical abstract