Urchin-like Bi2S3 nanostructures with rich sulfur vacancies for ppb-level NO2 sensing

The unique features of Bi2S3 enable it to be a promising candidate for preparing high-performance NO2 gas sensors. However, pristine Bi2S3 is usually inert for effective detection of ppb-level NO2 at room temperature owing to the lack of active sites. Herein, urchin-like Bi2S3 nanostructures with rich-defects were designed and prepared by a one-step hydrothermal method to realize ppb-level NO2 detection at room temperature. The optimal sensor based on urchin-like Bi2S3 with sulfur defects demonstrated an ultrahigh sensing response of 21.7 (almost 13 times higher than that of pristine Bi2S3) and a short response/recovery time of 42/36 s to 1 ppm NO2. In addition, an ultralow theoretical detection limit of 3 ppb was achieved for the sensor. The improved sensing performance could be ascribed to the numerous sulfur vacancies and the distinctive hierarchical structures, which promote the adsorption of NO2 molecules and boost charge transfer between NO2 and Bi2S3. This study would provide a new perspective on nanostructured materials for NO2 sensing at room temperature.