Heterostructures of hematite-sensitized W18O49 hollow spheres for improved acetone detection with ultralow detection limit

Heterostructures of metal oxide semiconductors present great potential for chemical sensor devices due to the fascinating properties endowed by the multiple materials and the heterointerface. In the present work, W18O49/alpha-Fe2O3 hollow heterostructures with different alpha-Fe2O3 contents are prepared by a hydrothermal method. The chemical composition and structure properties are characterized by multiple techniques. The gas sensing study demonstrates that the W18O49/alpha-Fe2O3 hollow heterostructures exhibit superior sensing performances toward acetone against pure W18O49. The composite containing 6.3 wt% alpha-Fe2O3 delivers the best sensor response and fast response-recovery speed (10 and 31 s), good selectivity, and low limit of detection (86 ppb). The superior gas sensing performance is interpreted by the functions of porous hollow structure and heterojunctions when introducing alpha-Fe2O3. This work provides a novel structure design for synthesis of high performances gas sensing materials for ppb-level acetone detection.