Fluoride-assisted highly-active tungsten oxide with modulating exposed facets and defect sites for efficient ppb-level acetone detection

Defect engineering is currently one of the most effective strategies to improve material sensing performance, which always need to be processed under harsh and complicated experimental conditions. Herein, a simple fluoride-assisted hydrothermal method is reported for preparing highly defective and active WO3. The obtained WO3 shows an urchin-like morphology and a mixed crystal structure. The optimized sensor based on the WO3 exhibits a high response, excellent selectivity, and good reproducibility to acetone at 200 °C. More precisely, the response to 0.5 ppm acetone attains 3.3 and the detection limit reaches the ppb-level, showing a potential application in noninvasive diagnosis of diabetes. The unique sensing performance can be attributed to the dominated h-WO3 with preferential exposed (0 0 2) facets and the increased structural defects in the synthesized WO3, resulting in an extent of local electric polarization on the surface and an easier and selective chemical adsorption to acetone molecules. The abundant oxygen vacancies act as preferential adsorption sites for absorbing oxygen species that can react with acetone molecules. The sensing mechanism for the unique sensing performance was further proved by a semi-in-situ controlled experiment. It is believed that the present work provides a simple and controllable approach to prepare highly active nanomaterials for application in various fields.