Highly permeable WO3/CuWO4 heterostructure with 3D hierarchical porous structure for high-sensitive room-temperature visible-light driven gas sensor

Light-driven gas sensors that featured with simple device structure, intrinsic safety and room-temperature sensing characteristic have received increasing attention in recent years. However, it is still a great challenge for light-driven gas sensors to achieve high sensitivity due to the low utility of photo-generated carriers caused by the undesired recombination of carriers in the sensitive layer. Herein, a visible-light driven gas sensor based on hierarchical porous (HPS) WO3/CuWO4 heterostructure with unique interconnected framework is developed. The gas sensor exhibits high sensitivity (Rg/Ra=82) to NO2 (1 ppm) under visible-light illumination at room-temperature, which is 8.2, 12.6 and 3.5 times higher than the sensors based on pure HPS WO3, HPS CuWO4 and WO3/CuWO4 nanoparticles. On one hand, this exceptional high sensitivity is mainly derived from the low recombination of photo-generated carriers mediated by interfacial electric field effect of heterojunction, and on the other hand, the excellent sensing performance is related to the enhanced gas adsorption that endowed by the light irradiation and the rich reactive sites of the unique HPS structure of WO3/CuWO4. This study is expected to provide an important reference for designing other high-sensitive room-temperature light-driven gas sensors.