UV-enhanced room temperature NO_2 sensor using ZnO nanorods modified with SnO_2 nanoparticles

摘要

ZnO/SnO_2 composite materials are synthesized by hydrolyzing SnO_2 on ZnO nanorods via the wet chem ical method. The gas sensing studies revealed that ZnO/SnO_2 exhibits a high response to NO_2 at room temperature under UV light emitting diode illumination. The highest response to NO2 was achieved by the Zn0/SnO_2 composite with Zn and Sn molar ratio of 1:1 (ZS3). The resistance of sensor based on ZS3 with UV light stimulation changed 1266-fold to 500 ppb NO_2 gas at room temperature. Furthermore, the selectivity, as well as response and recovery properties, of the sensor was improved remarkably by UV light irradiation. The ZnO/SnO_2 heterojunction model and the increased photo-generated electrons are proposed to elucidate the gas sensing mechanism.