Facile synthesis of SnO2 nanopowders on laser-patterned ITO electrodes for fast response NO2 gas sensors

This research focused on the synthesis of tin oxide (SnO2) by a facile sol-gel method because its advantage had a low-cost process. SnO2 was then annealed from 300degree celsius to 700degree celsius to obtain crystal nanopowders with different surface morphologies and grain sizes. In addition, ultraviolet laser processing equipment was used to fabricate an interdigitated structure on indium tin oxide (ITO) films coated on glass plates as an electrode layer of gas sensors. The annealed SnO2 nanopowder was drop-cast on the interdigitated ITO electrode as a gas detection layer. The developed gas sensors were used to detect air pollution. Moreover, a SEM, an XRD, and a four-point probe were applied to measure the morphologies, structural characteristics, and electrical properties of ITO thin films and SnO2 nanopowders, respectively. After gas detection tests, the gas sensor based on SnO2 nanopowders annealed at 600 degree celsius demonstrated a relatively large response of 9.7% and fast response and recovery times of 12 s and 16 s. Furthermore, the SnO2 nanopowder-based gas sensor at a NO2 concentration of 5 ppm had better repeatability with an average response of 9.57 +/- 0.22% after the 11-cycle test and an excellent sensitivity to NO2 compared to the gases CO2, H-2, NO, CO, and NH3.