Photocatalytic Activity of Composites Based on ZnO Tetrapods and Magnetite Nanoparticles

The research of zinc oxide tetrapods is a promising direction in the nano- and micro-materials field due to their unique properties. Firstly, the shape of tetrapods prevents their aggregation which is shortcomings of spherical and rod nanostructures. Secondly, zinc oxide is a non-toxic and biocompatible material. It makes zinc oxide structures are well suited for environmental, energy, and biomedical applications. Photocatalysis is one of zinc oxide's key applications because of the high efficiency of reactive oxygen species (ROS) generation, i.e. superoxide radicals and hydroxyl radicals. Surface passivation of zinc oxide tetrapods with magnetic nanoparticles can increase their photoactivity due to effective charge separation which is useful in photocatalysis. Moreover, induced magnetic properties can be used for magnetic separation. In this work, magnetite nanoparticles were chosen as the magnetic component since they have high magnetic susceptibility, demonstrate biocompatibility and low toxicity. Various approaches to a simple formation method of such structures are considered. The composites are obtained by mixing components in water in combination with: (i) ultrasound, (ii) magnetic stirring, (iii) vortex. The samples are studied using scanning electron microscopy, absorption and luminescence spectroscopy. The results confirm that magnetite nanoparticles bind to the zinc oxide tetrapods surface in all three approaches. The photocatalytic activity of the composites is investigated using methylene blue and methyl orange as ROS indicators under light irradiation and is compared with one of the pure zinc oxide tetrapods.