Highly Sensitive LaFeO₃-Based Sensor for Efficient Isoamyl Alcohol Detection

The nuanced response patterns of electronic noses to a diverse array of gases, coupled with the intricate composition of emissions from wheat during mildew infestation, render them a highly efficient tool for the swift identification of wheat mildew. Isoamyl alcohol is one of the early wheat mildew biomarkers, and LaFeO3 exhibited excellent sensing behavior toward it. LaFeO3 microspheres were synthesized by hydrothermal reaction with the precursor of the lanthanum-iron nitrate-citric acid system. The roles of temperature and citric acid content on the particle size, grain size, and chemical activity of the products were examined. Correspondingly, the sensitivity of the products to isoamyl alcohol under different hydrothermal parameters was investigated to determine the optimal hydrothermal parameter and various sensing properties of the optimal product were systematically studied. Due to the synergistic effect of specific surface area and chemical activity, the product performed superior sensitivity, repeatability, long-term stability ( $258.6 \pm 11.7$ @ 50 ppm for 15 days), and acceptable selectivity to isoamyl alcohol when the atomic ratio of citric acid, La, and Fe is 6:1:1 while the hydrothermal temperature is 180 °C. LaFeO3-based sensors exhibited outstanding sensitivity and detection capability (LOD = 136 ppb) at low concentrations, illustrating that this work may shed light on the sensing material design for the efficient detection of isoamyl alcohol. The capability of the LaFeO3-based gas sensor to detect complex volatile organic chemicals was verified, allowing it to be employed in wheat mildew monitoring.