Effect of fuel type on solution combustion synthesis and photocatalytic activity of NiFe$_2$O$_4$ nanopowders

Nickel ferrite nanopowders were obtained under conditions of solution combustion with the addition of various types of organic fuels (glycine, ascorbic acid, oxalic acid, and malic acid) and studied as photocatalysts in the photodegradation of methylene blue. Photocatalytic measurements were carried out under the action of visible light in model dye solutions. The highest photocatalytic activity was found in the case of a sample synthesized using malic acid as a fuel and in which the largest specific surface area (128.1 m$^2$/g) and the smallest particle size (18 nm) were observed. The obtained dependences of the photocatalytic activity of the synthesized samples demonstrate its strong dependence on morphological and structural parameters. Thus, with an increase in the particle size and a decrease in the specific surface area, a decrease in the efficiency of a photocatalyst based on nickel ferrite is observed. In addition, the use of various types of fuels made it possible to obtain aggregates of various shapes and sizes up to several tens of micrometers. The resulting rate constants were established to vary from 0.00756 to 0.00867 min$^{-1}$.