Preparation and Gas-Sensitive Properties of SnO₂@Bi₂O₃ Core-Shell Heterojunction Structure

The SnO₂@Bi₂O₃ core-shell heterojunction structure was designed and synthesized via a hydrothermal method, and the structure and morphology of the synthesized samples were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). Based on the conclusions from XRD and SEM, it can be observed that as the hydrothermal temperature increases, the content of Bi₂O₃ coated on the surface of SnO₂ spheres gradually increases, and the diameter of Bi₂O₃ nanoparticles also increases. At a hydrothermal temperature of 160 °C, the SnO₂ spheres are fully coated with Bi₂O₃ nanoparticles. This paper investigated the gas-sensitive performance of the SnO₂@Bi₂O₃ sensor towards ethanol gas. Gas sensitivity tests at the optimal operating temperature of 300 °C showed that the composite prepared at 160 °C achieved a response value of 19.7 for 100 ppm ethanol. Additionally, the composite exhibited excellent response to 100 ppm ethanol, with a response time of only 4 s, as well as good repeatability. The excellent gas-sensitive performance of the SnO₂@Bi₂O₃ core-shell heterojunction towards ethanol gas is attributed to its p-n heterojunction material properties. Its successful preparation contributes to the realization of high-performance heterostructure ethanol gas sensors.