ZnFe2O4/ZnO:Ga/Glass Heterostructure as Peroxidase Enzyme Mimetics for Hydrogen Peroxide Sensing

We report here a method for synthesizing ZnO:Ga and ZnFe2O4 films and ZnFe2O4/ZnO:Ga heterostructure and studying them as peroxidase enzyme mimetics for hydrogen peroxide determination and simulation-based detection has been proposed. A method for forming ZnO:Ga films by the DC magnetron sputtering method and ZnFe2O4 films and ZnFe2O4/ZnO:Ga heterostructures by the RF-sputtering method using a target consisting of ZnFe2O4 nanoparticles has been described. Thus, the procedure for synthesizing a heterostructure, which is based on the principle of self-assembly in a glow discharge plasma generated by a magnetron sputtering source, the cathode of which is a target consisting of zinc ferrite nanoparticles, has been optimized. Using the SEM and AFM methods, it has been revealed that with an increase in the argon pressure to 8.1 Pa, intergranular voids are formed in the resulting films due to the occurrence of the shading effect. These conditions provide the formation of a structure with a developed surface. This in turn typically leads to an increase in the valence electron concentration due to a large number of broken interatomic bonds and the formation of a large number of free oxygen sites on the film surface, which are donor centers involved in the redox process. Experimental results showed that the ZnFe2O4/ZnO:Ga film heterostructure exhibits peroxidase-like activity in a linear range of 0.017–0.240 μM. In addition, the color change dependent on hydrogen peroxide concentration can offer a convenient approach to detecting H2O2 both with the naked eye and spectrophotometrically. Therefore, the ZnFe2O4/ZnO:Ga film heterostructure is a promising candidate for the colorimetric detection of H2O2, ascorbic acid, and similar oxidizers.