High-performance hydrogen sulfide gas sensor based on ZnFe2O4/MoO2 in chip

Hydrogen sulfide (H 2 S) is a highly toxic gas commonly encountered in industrial settings, posing substantial health risks to workers. Therefore, the development of sensors with optimized operating temperatures, rapid detection speeds, and broad measurement ranges is of paramount engineering significance. In this study, ZnFe 2 O 4 /MoO 2 nanocomposites were synthesized using a hydrothermal method, and, for the first time, MEMS-based gas sensors utilizing ZnFe 2 O 4 /MoO 2 nanocomposite films were employed for hydrogen sulfide detection. The structural composition and morphology of the ZnFe 2 O 4 /MoO 2 (2:1) samples were characterized through X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). The gas sensitivity of ZnFe 2 O 4 /MoO 2 toward H₂S was systematically investigated. Gas sensitivity tests demonstrated that the ZnFe 2 O 4 /MoO 2 composite sensor exhibited a response value of 19.177 at 5 ppm hydrogen sulfide, which is 5.2 times greater than that of ZnFe 2 O 4 , the current dominant material for H₂S detection. Furthermore, the ZnFe 2 O 4 /MoO 2 composite sensor demonstrated a detection limit as low as 1 ppm and exhibited significantly faster response and recovery times (13 s and 11 s, respectively, for 5 ppm H₂S). The ZnFe 2 O 4 /MoO 2 (2:1) nanocomposite sensor exhibited excellent stability, sensitivity, and remarkable selectivity. This enhanced gas-sensing performance is attributed to the formation of n-n heterojunctions between ZnFe 2 O 4 and MoO 2 , as well as the optimized nanomorphology of the composite. Therefore, the ZnFe 2 O 4 /MoO 2 sensor presents a promising solution for hydrogen sulfide detection in industrial applications.