P-type Sb doping hierarchical WO3 microspheres for superior close to room temperature ammonia sensor

Nanosheet-assembled microspheres of tungsten oxide doped with antimony were synthesized via hydrothermal method. Sb doping changed the valency of W, promoted a partial crystal phase transition from orthorhombic to hexagonal, and modified the surface morphology. Further, WO 3 is an n-type semiconductor and is sensitive to gases above 100 °C. The Sb-WO 3 sensors in this work were p-type semiconductors from 25 °C to 65 °C, and exhibited excellent sensitivity, fast response and good recovery properties to NH 3 . At 35 °C, the detection limit of 1 at% Sb-WO 3 for ammonia was 200 ppb, and the sensor shows a good stability and selectivity toward several possible interferent. The substantially improved sensing performance of the Sb-WO 3 sensors at near room temperature could be mainly attributed to the change of the W valency promoted via Sb doping. • Microspheres composed of Sb doped WO 3 nanosheets were prepared by hydrothermal method. • The Sb-WO 3 sensor in this work was a p-type semiconductor at near RT, and exhibits excellent sensitivity to NH 3 . • The improved sensing performance of the Sb-WO 3 at near RT could be attributed to the change of the W valency by Sb doping.