Low-cost high- performance NO2 sensor based on nanoporous indium tin oxide (ITO) film

Abstract The electrochemical corrosion of commercial indium tin oxide (ITO) glasses enabled the preparation of a low-cost nanoporous ITO film-based sensor exhibiting a high NO2 response. The NO2 sensing characteristics of the nanoporous ITO films were studied at different processing voltages and test temperatures. Under the optimal test condition (10 V, 100 °C), the response of the sensor was 3.1 to 0.1 ppm NO2 and 180–500 ppm NO2. Compared with previous literature, the as-obtained sensor has a low working temperature (100 °C), wide detection range (0.1–500 ppm NO2), and high response (12.34 1 ppm NO2). Moreover, the sensor exhibited excellent repeatability and a high selectivity toward NO2. X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, and Brunauer-Emmett-Teller was employed to study the structural changes of the ITO film due to electrochemical corrosion and revealed a nanoporous structure with abundant surface hydroxyl groups. The influences of the nanoporous structure and surface hydroxyl groups on the response are discussed in detail. Finally, it was found that the Langmuir model provided a good fit to the working curve of the sensor, and thus explains the mechanism of the enhanced response based on the nanoporous structure. Overall, this study demonstrates that an electrochemically corroded ITO film is suitable for detecting NO2.