Selectivity enhancement of SnO2 nanofiber gas sensors by functionalization with Pt nanocatalysts and manipulation of the operation temperature

We report on facile synthesis of SnO2 nanofibers (NFs) functionalized by Pt nanoparticles (NPs) with various loading contents (0.05-0.4 wt%) and their gas response toward H2, NO2, NH3, CO, and SO2 gases as a function of the operation temperature (100-450 °C) and gas concentration (0.125-2.5 ppm). Mesoporous SnO2 NFs with large surface-to-volume ratio, which facilitates sensitive gas response, were synthesized by electrospinning followed by subsequent calcination at 500 °C for 2 h. Colloidal Pt NPs synthesized by simple polyol method were immobilized on SnO2 NFs as a catalytic sensitizer to H2 oxidation. The gas sensing properties and response kinetics were significantly affected by the Pt NPs and the operation temperature. It was found that 0.1 wt% Pt-loaded SnO2 sensor showed the highest H2 response (Igas/Iair = 16.6 at 2.5 ppm) at 300 °C. A remarkably high NO2 response (Iair/Igas = 57.0 at 2.5 ppm) was achieved in the case of pristine SnO2 sensor at 150 °C. This work demonstrates that sensitive and selective detection of H2 and NO2 gases with negligible cross-response to interfering gases such as NH3, CO, and SO2 can be obtained by decoration with Pt NPs on metal oxide NFs in conjunction with manipulation of the operation temperature.