Comparative study of gas sensor performance of SnO2 nanowires and their hierarchical nanostructures

In this study, SnO2 nanowires (NWs) were synthesized by two different thermal evaporation processes and hierarchical SnO2 nanostructures were prepared through a combination of the two processes without reseeding of Au catalyst. Field emission scanning electron microscopy studies showed that the shape of the core NWs become distorted and attached to large quantities of quasi-one-dimensional nanostructures, mostly NWs and nanobelts. The crystal structure of these as-prepared hierarchical SnO2 nanostructures was identified to coincide to the normal rutile structure. Photoluminescence properties are similar among the samples with a strong peak emission band centered at 620 nm that is attributed to a defect-state-related emission. The gas sensing performance of SnO2 NWs and their hierarchical nanostructures were simultaneously investigated by testing with liquefied petroleum gas and NH3 gas at different concentrations and operating temperatures. Results reveal that hierarchical SnO2 nanostructures have enhanced gas sensing performance in comparison with SnO2 NWs materials. The gas sensing mechanism of SnO2 hierarchical nanostructures was also discussed. Results indicate that hierarchically porous SnO2 architectures are highly promising for gas sensor applications.