Highly sensitive SnO2 hollow nanofiber-based NO2 gas sensors

SnO2 hollow nanofibers (HNFs) with diameters of 300–500 nm were fabricated via electrospinning of templating nanofibers and RF-sputtering of SnO2 thin overlayers (15–20 nm thick and comparable grain size) followed by heat-treatment at 450 °C. Gas sensors using these HNFs exhibited n-type gas sensing characteristics and an enhanced gas response to 2 ppm NO2 (Rgas/Rair = 81.4) as compared to that (Rgas/Rair = 19.9) of planar SnO2 thin films. The enhanced response to NO2 is attributed to the greater accessible active area and the greater space charge modulation depth associated with the hollow thin walled structures.