Investigation of Hierarchical Gas-Sensing ZnFe2O4 Nanostructures

Nowadays a significant issue lies in developing approaches to diagnosing the surface composition and structure of mixed oxide materials, including in local areas. The possibilities of X-ray photoelectron spectroscopy, energy-dispersive X-ray spectroscopy, and electron backscatter diffraction in the local region to study the surface composition of a hierarchical ZnFe2O4 nanostructure are shown. This nanostructure is synthesized by the post-treatment of zinc oxide nanowires in an aqueous solution of an iron salt. The studies show that zinc, iron, and oxygen are uniformly distributed over the surface of the sample. It is found that the electron-backscatter-diffraction pattern corresponds to the ZnFe2O4 compound. Using X-ray photoelectron spectroscopy, iron on the surface of the sample is shown to exist in the Fe3+ and Fe2+ states, and oxygen is present both in the crystal lattice and in the adsorbed state. We make an assumption regarding the processes that occur in the synthesis of a hierarchical structure that cause these properties. It is shown that the sensor signal of the hierarchical structure during the detection of isopropyl-alcohol vapor with a concentration of 1000 ppm–1 exceeds the signal of zinc oxide nanowires.