Porous ZnO/rGO Nanosheet‐Based NO₂ Gas Sensor with High Sensitivity and ppb‐Level Detection Limit at Room Temperature

Abstract

Abstract High‐performance gas sensors are highly desirable for environmental monitoring, clinical medicine, and industrial production. Herein, a gas sensor with excellent sensing response at room temperature is presented based on zinc oxide/reduced graphene oxide (ZnO/rGO) composites. The ZnO/rGO composites with various contents of rGO and the pure ZnO are successfully fabricated by a facile hydrothermal method. Particularly, the ZnO/rGO sensor with 1.5 mL of the rGO exhibits highest sensing response in a wide range from 5 ppb to 10 ppm NO 2 concentration and its response arrives at 13.46 when exposed to 2 ppm NO 2 at room temperature. Furthermore, ZnO/rGO sensors show short response time (2 ppm, 26 s) and recovery time (2 ppm, 164 s) at room temperature. The proposed ZnO/rGO sensors present high sensitivity, excellent reproducibility, and stability. In addition, the density functional theory (DFT) calculations show that the increased electrical conductivity under exposure of NO 2 gas are attributed to the numerous reactive sites and carrier mobility of rGO. These results demonstrate that ZnO/rGO gas sensor has huge potential for applications in industrial and environmental monitoring.