Modulated Preparation of ZnO@ZIF-8 Core-Shell Nanorods and Research on Their Gas-Sensitive Characteristics

Abstract Ammonia (NH3) is a commonly encountered yet potentially dangerous gas. Therefore, fabricating a sensor that exhibits a favorable response to ammonia gas at room temperature (RT, ~25°C) holds substantial practical significance. Here, the gas-sensitive response of ZnO to 1000 ppm NH3 was adjusted by modifying the ratios of the surfactant CTAB. Notably, ZnO responded best to NH3 when 50% CTAB was added (436). Based on this, we fabricated core-shell ZnO@ZIF-8 sensitive materials with selective response to NH3 by hydrothermally etching a certain amount of ZnO on the ZnO surface with 2-methylimidazole. The response value of ZnO@ZIF-8 to 1000 ppm NH3 gas (1485) was significantly higher than that of pure ZnO (436), with a threefold enhancement in the response value. Additionally, due to the contribution of the hydrophobic group (-CH3) in ZIF-8 to the hydrophobicity of the composite material, the average response value of ZnO@ZIF-8 was merely 6 at 96% humidity, which can effectively mitigate the interference of water molecules in the natural environment during gas detection. This work offers novel methods for the advancement of ZIF-8 materials within the domain of gas sensing.