Acetone gas sensor based on Nb2O5 @SnO2 hybrid structure with high selectivity and ppt-level sensitivity

For air quality monitoring and medical diagnosis, the development of sensors for low-concentration acetone gas is desirable but challenging. In this study, Nb2O5 nanoparticles were loaded onto SnO2 nanosheets to build a hybrid structure with a loose structure as sensor materials. The spiky Nb2O5 (s-Nb2O5) exhibited a higher response for acetone detection than the Nb2O5 nanorods (r-Nb2O5). Gas sensors based on the s-Nb2O5 @SnO2 composite exhibited a remarkable enhancement in the acetone sensing-performance, with high response, a low detection limit, and good selectivity at 250 celcius. The response of the s-Nb2O5 @SnO2 composites to 500 ppb acetone was nearly 37, which was superior to that of the pure SnO2 nanosheets, with a response of 12; the experimental and theoretical limits of detection (LODs) were 40 ppt and 4.77 ppt, respectively. The present experimental and theoretical LODs are the lowest among those reported for gas sensors based on metal oxide semiconductors. The high response likely originates from the n-n heterostructure, synergistic effect, and the existence of a large amount of chemisorbed oxygen. Additionally, the loose structure played significant roles in the enhanced sensing performance. Such favorable acetone sensing performance endows these s-Nb2O5 @SnO2 heterostructures with potential applicability in ppt-level acetone gas detection.