Electrospun SnO2 nanofiber mats with thermo-compression step for gas sensing applications

SnO2 nanofiber mats fabricated through electrospinning followed by thermo-compression and subsequent calcination steps exhibited unique morphologies facilitating efficient gas transport into the layers combined with high surface area (similar to 73.5 m(2)/g, measured by BET) and small grain size (similar to 5-15 nm), which are well suited for ultrasensitive gas detection. Single SnO2 nanofibers were found to have a belt-like structure of closely packed nanocrystallites, facilitating excellent adhesion to the substrate and good electrical contact to the electrodes. I-V measurements of single SnO2 nanofibers displayed ohmic behavior with electrical conductivity of 1.5 S/cm. Gas sensor prototypes comprising a random network of SnO2 fibers exhibited high sensitivity when exposed to NO2 at 225A degrees C and CO at 300A degrees C. A detection limit of 150 ppb NO2 at 185A degrees C was estimated by extrapolating the sensitivity results obtained on exposure to higher gas concentrations, demonstrating potential of achieving ultra-sensitive gas detection at low operating temperatures enabled by the present synthesis method.The authors gratefully appreciate Dr. Kathy Sahner's support for sensing characterization and helpful discussion. This work was supported by KIST research program of one of the authors (I.-D. K) under Grant No. 2E21760. The work at MIT was supported, in part, by the National Science Foundation under Grant No. ECS-0428696