Ppb-Level NO₂ Sensor with High Selectivity Fabricated by Flower-like Au-Loaded In₂O₃

• Published in: Chemosensors
• Main Authors: Ji Zhang, Fangfang Zhang, Xu Li, Qingji Wang
• Format: Article
• Language: English
• Published: MDPI AG 2023-05-01
• Subjects: NO₂ sensor; <i>flower-like</i>; Au-loaded In₂O₃; low detection limit; high selectivity
• Online Access: https://www.mdpi.com/2227-9040/11/5/289

With increasingly serious environmental problems caused by the improvement in people’s living standards, the number of cars has increased sharply in recent years, which directly leads to the continuous increase in the concentration of NO₂ in the air. NO₂ is a common toxic and irritant gas, which is harmful to both the human body and the environment. Therefore, this research focuses on NO₂ detection and is committed to developing high-performance, low detection limit NO₂ sensors. In this study, flower-like Au-loaded In₂O₃ was successfully fabricated using the hydrothermal method and the wet impregnation method. The morphological features and chemical compositions of the as-prepared samples were characterized using SEM, TEM, XRD and XPS. A variety of sensors were fabricated and the gas-sensing properties of sensors were investigated. The results indicate that the sensor based on 0.5 mol% Au/In₂O₃ shows a response value of 1624 to 1 ppm NO₂ at 100 °C, which is 14 times that based on pure In₂O₃. Meanwhile, the detection limit of the sensor based on 0.5 mol% Au/In₂O₃ for NO₂ is 10 ppb, and the response value is 10.4. In addition, the sensor based on 0.5 mol% Au/In₂O₃ also has high selectivity to NO₂ among CO, CO₂, H₂, CH₄, NH₃, SO₂ and H₂S. Finally, the sensitization mechanism of Au/In₂O₃ was discussed, and the reasons for improving the performance of the sensor were analyzed. The above results and analysis demonstrate that the gas-sensing attributes of the sensor based on 0.5 mol% Au/In₂O₃ to NO₂ improved remarkably; at the same time, it has been proved that the composite material has extensive potential in practical applications.