Synthesis of enriched oxygen vacancy TiO₂ microsphere with rapid response to isopropylamine and its application in herbicide detection

Real-time detection of herbicides has been a challenge for the application of metal oxide gas sensors. In this paper, we report the application of TiO₂ sensors with oxygen vacancies for the detection of isopropylamine. Spherical structure with oxygen vacancies was successfully prepared by a simple one-step hydrothermal method combined with ionic liquid as morphology regulator. The morphology and structure of the materials were analyzed using XRD, SEM and TEM. Further studies reveal that the oxygen vacancies in this material play an important role in the detection of isopropylamine. The sensor exhibits excellent selectivity, moisture resistance and long-term stability. The response is 61.7–100 ppm isopropylamine, along with fast response time of 22 s. It is noteworthy that the lower limit of detection for isopropylamine can reach 0.2 ppm, which is very meaningful to practical application of detecting gas residues. The excellent performance can primarily be attributed to the formation of abundant oxygen vacancies into the material, which increases the adsorption capacity of gas molecules. This new sensing design strategy offers a vital reference to extend the application of non-metallic elements doped metal oxide semiconductors.