Sensitive and selective evaluation of the 3-hydroxy-2-butanone biomarker via gas sensors based on WO3 nanomaterials with multiple morphologies

Listeria monocytogenes is a foodborne pathogenic bacterium that can survive under a wide range of temperature and pH conditions, with a mortality rate of up to 20% −30%. One emerging and validated method of indirectly assessing Listeria monocytogenes in food is detecting 3-hydroxy-2-butanone gas. In this study, WO3 nanoflowers (a diameter of 2.8 µm) and two different hierarchical structures of WO3 were successfully synthesized. XRD, BET, SEM, and TEM were applied to characterize their morphology, microstructure, catalytic structure, and specific surface area. For assessing their gas sensing performances toward 3-hydroxy-2-butanone, a series of gas sensitivity indicators were purposefully measured. The results indicated that WO3 nanoflowers had the best gas sensing performance including high sensitivity (81 @ 20 ppm), rapid response-recovery time (4 s/9 s), low LOD (1 ppm) and good stability. Moreover, by analysing the various characterization results of these materials, the sensitivity mechanism was explained in detail as well.