WO3 nanotubes SnO2 nanoparticles heterointerfaces for ultrasensitive and selective NO2 detections

In this work, the Sn-O2 nanoparticles WO3 nanotubes heterostructures are reported for the first time and systematically investigated for NO2 detection. The hybrid SnO2 WO3 sensing films were fabricated by thermal decomposition of WS2 nanotubes loaded flame-spray-made SnO2 nanoparticles with varying WS2 contents (0.5-10 wt%). Characterizations by X-ray diffraction, electron microscopy, thermogravimetric, differential thermal analysis and X-ray photoelectron spectroscopy indicated that hexagonal WS2 nanotubes were completely converted to orthorhombic W-O3 nanotubes and well-dispersed within polycrystalline tetragonal SnO2 nanoparticles. The gas-sensing results revealed that the addition of WO3 nanotubes to SnO2 nanoparticles led to the substantial enhancement of sensor response towards NO2. Specifically, the 5 wt% WO3 loaded SnO2 sensor exhibited an ultra-high response of similar to 12,800 to 5ppm NO2 with good recovery stabilization at a low optimal operating temperature of 150 degrees C. In addition, the WO3-loaded SnO2 sensor presented high NO2 selectivity against CH4, NO, C2H5OH, C3H6O, H2S and H-2. The enhanced NO2 sensing properties may be ascribed to the formation of WO3 nanotubes/SnO2 nanoparticles n-n hetero interfaces and the enhanced accessible surface areas of highly active sites for chemisorbed NO2 species. Therefore, SnO2 nanoparticles WO3 nanotubes composite structure prepared by flame spray pyrolysis and thermal decomposition is highly promising for highly sensitive and selective NO2-sensing applications.