A Humidity-Insensitive NO₂ Gas Sensor with High Selectivity

Gas sensors based on semiconductor-metal-oxide nanomaterial have recently emerged due to their advantages of offering large surface to volume ratio. Unfortunately, these sensors are vulnerable to environmental humidity and lack of selectivity when exposed to common gases in air. In this letter, a novel morphology of ZnO nanomaterial is proposed for fabricating NO₂ gas sensor through our customized vapor trapping chemical vapor deposition process. By operating the fabricated gas sensors at the room temperature, high sensing performance, including a large output response of 11.06 and a short response/recovery time of 107/124 s, is achieved for 20-ppm NO₂. Moreover, the sensor response remains stable under humid environment up to 76%RH. In addition, the extensive experimental results indicate that our fabricated NO₂ gas sensors exhibit high selectivities of 61.7, 42.8, and 54.4 dB for different target gases of H₂, CH₂O, and C₆H₆, respectively. These features will enable the mass fabrication of miniaturized, cost-effective, and highly robust gas sensor suitable for real-life application.