Perovskite-structured LaCoO3 modified ZnO gas sensor and investigation on its gas sensing mechanism by first principle

In this work, LaCoO3 (LCO) nanoparticles were synthesized by sol-gel method and modified on the surface of ZnO. The LaCoO3-modified ZnO (LCO/ZnO) nanometer flake materials were successfully prepared, the microstructure, surface properties and internal composition of which were analyzed by various characterization tools. Compared with the traditional ZnO sensor, LCO/ZnO sensor has been greatly improved in terms of gas-sensitive response, response time and recovery time. At the optimal operating temperature of 320 °C, the maximum response of LCO/ZnO sensor to 100 ppm ethanol gas can reach 55, which is 6 times higher than that of pure ZnO sensor. Meanwhile, the response time and recovery time of LCO/ZnO sensor were reduced to 2.8 and 9.7 s, respectively. All the results demonstrate that LCO is an excellent catalyst for improving the gas-sensitive performance of metal oxide semiconductor sensors. The first principle was used to analyze the surface properties, and study the sensitization mechanism of LCO in detail from the adsorption process of surface oxygen, heterojunction action and LCO catalytic oxidation process for ethanol sensing. The improvement of the sensing performance of LCO/ZnO sensor was attributed to the increase of surface adsorbed oxygen content and the strong catalytic oxidation activity of LCO.