Optimisation of nickel ferrite production conditions for the preparation of magnetic composite photocatalysts

Ferrites of non-ferrous metals are promising magnetic catalysts that can be easily separated from the reaction mixture after use by applying a magnetic field. However, these materials have a fast electron-hole relaxation time, which reduces their activity in photoreactions. This problem is overcome by creating hybrid nanostructures based on ferrites, for example with zinc oxides. The catalytic activity of such structures depends highly on the method of their synthesis. In this work, the alkaline co-precipitation of Fe2+ and Ni2+ ions, which have similar values for hydroxides, was used to obtain stoichiometric and homogeneous nickel ferrite precursors. The influence of the reaction parameters on the purity of the nickel ferrite phase and the size of the particles was studied using the experimental design technique. Spherical nanoparticles 15.9 ± 1.1 nm in diameter were produced under the optimal conditions identified. Based on the obtained material, NiFe2O4/ZnO magnetic composites of different quantitative compositions were prepared. The photocatalytic activity of the hybrid structures was demonstrated by photodegradation of crystal violet dye.