Ultrasensitive Detection and In-Depth Chemical Mechanism Study Toward Ethanol Vapor for LaCoO3/SnO2 Nanoflower

LaCoO3 nanoparticles were synthesized using the sol-gel method, and LaCoO3/SnO2 nanoflower-like materials were successfully prepared by using the hydrothermal method. Various characterization techniques were employed to analyze their microstructures and elemental compositions. LaCoO3/SnO2 exhibited significant improvements in gas response, response time, and selectivity compared to SnO2 sensors. At the optimal operating temperature of 260 °C, LaCoO3/SnO2 demonstrated a maximum response of 219–100 ppm ethanol vapor, which was 8.4 times higher than that of pure SnO2. Additionally, the response time of LaCoO3/SnO2 was reduced to 17 s and showed good selectivity. The improved gas-sensitive performance of LaCoO3/SnO2 was probably due to the heterojunction generated by the introduction of LaCoO3 and the increase of specific surface area. The density of states, adsorption energy, and charge density of adsorbed ethanol gas before and after the modification of SnO2 by LaCoO3 were analyzed using the first principles to further explain the enhancement mechanism of LaCoO3/SnO2 heterojunctions.