Highly sensitive near room temperature operable NO2 gas-sensor for enhanced selectivity via nanoporous CuO@ZnO heterostructures

In the combustion of fossil fuels, various noxious gases are released. Therefore, it is revered to design gas sensors with excellent performance and low power consumption. In this work, we account the superior nitrogen dioxide (NO2) sensing characteristics of pristine CuO and CuO/ZnO heterostructures at room temperature (RT -30 ℃). The fabricated CuO/ZnO sensor manifested a maximum sensitivity of 337% for 5 ppm of NO2 gas, relatively rapid response/recovery time of 18/32 s and detection limit is to be 155 ppb at RT (30 ℃). The CuO/ZnO heterostructures reveals the outstanding response against NO2 and imperceptible cross-response to other gases. Furthermore, the fabricated gas sensor has good repeatability and excellent stability of 92%. The increased sensitivity was ascribed owing to the synergistic effect of CuO and ZnO. Especially, the nanoporous heterostructure may promote NO2 gas adsorption and providing a large number of reaction center between chemisorbed oxygen species and NO2 molecules. In particular, the heterostructures provide to make interface and charge transfer at the interaction between CuO and ZnO to chemisorbed oxygen species. Simultaneously, the heterostructure helps to offer a large number of active sites for NO2 molecules. These studies will offer a new pathway of heterostructured metal oxide semiconductor for gas sensor application at RT (30 ℃).