Bilayer Polyaniline-WO3 Thin-Film Sensors Sensitive to NO2

In this work, a novel bilayer polyaniline-WO3 (PANI-WO3) thin film on the fluorine-doped tin oxide (FTO) glass substrate was prepared by hydrothermal synthesis and in situ chemical oxidative polymerization methods. Until now, no one has ever made attempts to use the PANI-WO3 composite on the FTO glass substrate to detect NO2 gas. The composite showed excellent sensing performance for NO2 detection at an operation temperature of 50 degrees C and a detection limit of 2 ppm. With regard to the PANI-WO3 hybrid, the response value for NO2 at 30 ppm is 60.19 and is three times higher than that for pure WO3 at SO degrees C. Besides, the PANI-WO3 hybrid had excellent stability. The improvement of gas sensing was assigned to the creation of p-n heterojunctions between p-type PANI and n-type WO3, larger specific surface, increase of oxygen vacancies, and a wide conduction channel provided by PANI.