Ag drives electron transfer and the ZIF-8 modified surface accelerates the reaction of ZnO with ammonia gas

In order to solve the problems of insufficiently rapid response and recovery and poor moisture resistance when zinc oxide is used as a gas sensitive material, a flexible frame material with hydrophobicity, ZIF-8, was introduced to modify the surface of ZnO, and then doped Ag nanoparticles, which can be electron sensitized with ammonia, to obtain Ag modified ZnO@ZIF-8 nanoparticles. At room temperature (RT, ∼25 °C), the response time of ZnO, ZnO@ZIF-8, and Ag modified ZnO@ZIF-8 nanoparticles to 500 ppm ammonia is 74.3 s, 20.2 s, and 8.0 s, and the recovery time is 36.0 s, 23.1 s, and 16.8 s, respectively. The fitting detection limit of Ag modified ZnO@ZIF-8 nanoparticles for ammonia was 83 ppm. Compared with pure ZnO, the moisture resistance of ZnO@ZIF-8 and Ag modified ZnO@ZIF-8 was significantly improved after coating with ZIF-8.