N-/S- dual doped C@ZnO: An excellent material for highly selective and responsive NO2 sensing at ambient temperatures

Nitrogen dioxide (NO2) is an extremely toxic gas and harmful to human health and the environment. Inhalation of NO2 reduces immunity to lung infections and causes respiratory problems such as wheezing, coughing, colds, flu, and bronchitis. To date, several sensors have been developed for the detection of NO2. Indeed, the development of highly sensitive and selective room temperature sensor with rapid response and recovery time could be called an “innovation” for metal oxide-based gas sensors for environmental remedy applications. Herein, we prepared ZnO nanospheres (ZNS), nitrogen-doped carbon-coated ZnO spheres ([email protected]), sulfur-doped carbon-coated ZnO spheres ([email protected]), and nitrogen-sulfur dual doped carbon-coated ZnO spheres ([email protected]) for NO2 sensing. Among them, the [email protected] exhibits excellent NO2 sensing characteristics with the sensor response (SR = Rg/Ra) of 730.4 and 31.2 at 100 and 25 °C, respectively. The limit of detection (LOD) of the [email protected] sensor is ~21 ppb at ambient temperature. The [email protected] hybrid nanocomposite sensor exhibits ultrafast response and recovery times of ~88 s and 305 s to 500 ppb of NO2 at 25 °C. Besides, the [email protected] sensor shows excellent selectivity to NO2, which is ~31 times higher than other interfering gases. The enhanced sensing characteristics of the [email protected] sensor is attributed to the synergy between the nitrogen-sulfur dual doped carbon and hierarchical mesoporous ZnO. The selective detection of NO2 with significantly rapid response and recovery time at 25 °C makes for intriguing the promising practical applications of our proposed [email protected] sensor.