High Response and Selectivity Ammonia Sensor Based on WO3/MoO3 Porous and Hollow Microsphere

In this paper, we synthesized a WO ₃ /MoO ₃ porous and hollow microsphere. Firstly, the WO ₃ nanorods were synthesized by one-step hydrothermal method. Secondly, the WO ₃ nanorods were added to the MoS ₂ precursor solution, and the mixture was further hydrothermally treated. Finally, the obtained samples were heated and oxidized in air to obtain WO ₃ /MoO ₃ hollow nanospheres. The morphology and microstructure of the composite were observed by SEM and TEM, and its crystal structure was characterized by XRD. The results showed that the gas response of WO ₃ /MoO ₃ is greatly improved by the addition of MoO ₃ . The response is up to 28000 to 100 ppm ammonia and the limit of detection is 100 ppb when the WO ₃ /MoO ₃ sensor is operated at the optimum operating temperature. It has basically no response to other volatile organic gases, which indicates that the sensor has an excellent selectivity. Furthermore, we also studied the gas sensing mechanism of WO ₃ /MoO ₃ porous and hollow sphere and the effect of different amount of WO ₃ on the gas response of the composite.