The "screening behavior" of lithium: Boosting HS selectivity of WO nanofibers.

An ideal way to boost the selectivity of sensing materials is that improving the sensitivity of the target gas while suppressing that of other interfering ones. Here, the "screening behavior" of the Li doped WO nanofibers (Li/WO NFs) have been discovered in suppressing the response from interfering gases, while elevating the HS sensing response. Beneficially, the HS response of Li/WO NFs sensor prototype is three times (R / R = 64@10 ppm) as high as that of the pristine WO ones (R / R = 21@10 ppm) at ~75% relative humidity and 260 °C. Moreover, Li/WO NFs sensor prototype presents the detection limit as low as 100 ppb. Particularly, the Li/WO NFs sensors detect simulated halitosis breath, of which the accuracy is comparable with gas chromatography. Theoretically, the decrease of the responses of Li/WO NFs to interfering gases is ascribed to the enhancement of the adsorption of water molecules by Li dopant. While the improved response to HS is attributed to stronger adsorption of HS and WO and to the increased defect oxygen. The "screening behavior" of Li doped into WO NFs provides a new strategy that might improve the selectivity of other gas sensing.