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 (∼73.5 m²/g, measured by BET) and small grain size (∼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 225°C and CO at 300°C. A detection limit of 150 ppb NO₂ at 185°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.