In Situ Growth of Oxygen Defect-Rich Ultrathin WO3 Nanosheets for Ultrafast Recovery NO2 Sensors

Ultrathin WO3 nanosheets (~10 nm) were successfully in situ grown on the surface of ceramic tubes by a facile method. Subsequently, abundant oxygen vacancies were purposely created on the surface of nanosheets through a direct annealing process. It was found that the increase of oxygen vacancies was the main reason for the great improvement of nitrogen dioxide (NO2) gas sensing performance. The gas sensor based on this oxygen defect-rich ultrathin WO3 nanosheet exhibited good selectivity and ultrafast response (6 s to 5 ppm) and recovery (about 5 s to 100 ppm) to NO2. The gas sensing response was about 234 to 100 ppm NO2 at 210 °C. Even at 30 °C, the gas sensor still presents a high response to NO2 (the response value of 10.48). Obviously, this work provides a viable strategy for the rapid detection of NO2 in daily life and industry.