Ordered mesoporous WO3/ZnO nanocomposites with isotype heterojunctions for sensitive detection of NO2

Ordered mesoporous WO3 nanocrystals have been successfully synthesized by a hydrothermal method using mesoporous silica of KIT-6 as a template and phosphotungstic acid as a precursor of WO3. The structure, morphology, and specific surface of WO3 nanocrystals were systematically characterized by XRD, SAXS, HR-TEM, and BET. To improve the sensing properties of WO3 to NO2, a series of different ZnO amounts were loaded on the mesoporous WO3 to construct nanocomposites with n-n heterojunction for the fabrication of NO2 sensors. The gas-sensing behaviors show that the sensor based on WO3/5 wt% ZnO composite to 1 ppm of NO2 not only exhibits the high response, but also has good selectivity and stability at operating temperature of 150 degrees C, which can be contributed to the large specific surface and porous channels provided by mesoporous structures, and the formation of n-n heterojunctions at interface between both oxides.