NO2 gas sensing with SnO2–ZnO/PANI composite thick film fabricated from porous nanosolid

SnO2–ZnO/polyaniline (PANI) composite thick film for NO2 detection was fabricated from SnO2–ZnO porous nanosolid and PANI by a conventional coating method. The SnO2–ZnO composite porous nanosolid was prepared by a solvo-thermal hot-press (SHP) method. It was found that the composite sensor has high selectivity and response to low concentration NO2 gas. Furthermore, the composite sensor also showed high stability to NO2 over a long working period at low optimum working temperature (180 °C). The response and recovery times of SnO2/PANI composite sensor (SZ20-P) were as short as about 9 and 27 s to 35 ppm NO2 at 180 °C, respectively. The experiment results show that both the pore structures of SnO2 porous nanosolid and the content of ZnO had effects on the sensor response of SnO2–ZnO/PANI composites, and the optimum content of ZnO was 20 wt.%. The possible sensing mechanism was discussed.