Sonochemical synthesis of hierarchical WO3 flower-like spheres for highly efficient triethylamine detection

Tungsten oxide (WO3) is an emerging sensitive material with high electronic mobility and excellent chemical stability. Herein, we synthesize hierarchical WO3 spheres assembled by sheet-like structures via a facile sonochemical strategy followed by the calcination process. The acidic environment and hydroxyl radicals released by hydrogen peroxide play crucial roles for the final formation of hierarchical WO3 flower-like spheres. The obtained hierarchical WO3 spheres are assembled by loosely connected sheet-like structures, which is convenient for the diffusion of gas molecules and the maximum utilization of sensing materials. The optimal WO3 sensor is endowed with an excellent response of 11.6 and an ultrafast response time of 3 s to 10 ppm triethylamine (TEA) at 205 °C. Furthermore, the WO3 sensor displays superior reusability, reliability in normal humidity conditions, and low theoretical limit of detection of 83 ppb. The excellent sensing properties are largely attributed to the unique nanostructures of hierarchical WO3 flower-like spheres, which promote the active surface reactions and facilitate TEA molecules diffusion into the sensing layers. Therefore, we provide a facile synthesis method for hierarchical WO3 flower-like spheres and their gas sensing applications.