Chromium-Doped ZnFe₂O₄ Nanostructures for Detection and Accurate Classification of Acetone

Abstract

The sensing properties of semiconducting metal oxides are influenced by dopants, which introduce point defects and tune their band structure. As a dopant ion, Cr is expected to disrupt the cation distribution in zinc ferrite (ZnFe2O4), influencing the electron transfer between cations and conductivity. Thus, the use of Cr dopant should overcome the high operating temperatures and selectivity issues that have hindered the practical application of ZnFe2O4-based nanosensors, effectively increasing the response variance for accurate gas classification using principal component analysis. Herein, a combustion method was used to synthesize fiber-like Cr-doped ZnFe2O4 nanostructures with different concentration levels of 0.0, 0.5, 1.0, and 1.5 mol %. Microstructural and morphological analyses were conducted using X-ray diffraction and electron microscopy. X-ray photoelectron spectroscopy and photoluminescence were used to analyze the electronic structure and identify the defects. The gas sensing results showed that the sensor based on 1.0 mol % Cr-doped ZnFe2O4 nanostructures had fast response/recovery (45 s/179 s) times and enhanced response of 283 to 90 ppm acetone at a low operating temperature of 90 °C. Moreover, the sensor based on 1.0 mol % Cr-doped ZnFe2O4 can be used as a single array sensor for gas classification. The improved sensing properties were attributed to structural defects and proper gas diffusion.