One-step synthesis of n-CdO/n-SnO2 heterojunction nanofibers for high-performance 3-hydroxy-2-butanone gas sensing

Listeria monocytogenes (LM) is a pathogenic bacterium which can release 3-hydroxy-2-butanone (3H-2B) as a biological indicator. We report a high-performance 3H-2B gas sensing strategy for the selective detection of LM. This strategy is realized by n-CdO/n-SnO2 hetero-nanofibers with controllable compositions, synthesized via a facile one-step electrospinning method. The tailored morphologies and microstructures of CdO/SnO2 nanofibers were systematically characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). With the introduction of CdO into SnO2 nanofibers, x-ray diffraction (XRD) and x-ray photoelectron spectroscopy (XPS) were performed to investigate the effects of crystal phases and elemental states on the 3H-2B sensing properties. According to the gas sensing results, the variation of Cd/Sn molar ratios has a great influence on the 3H-2B sensing properties of CdO/SnO2 nanofibers. The maximum response (45) to 5 ppm 3H-2B is found for 5 mol% CdO/SnO2 nanofibers at 260 degrees C. Meanwhile, 5 mol% CdO/SnO2 nanofibers exhibit a short response/recovery time (9 s/5 s), outstanding stability, and discriminative selectivity to 3H-2B. The enhanced sensing performance is mainly attributed to the synergy between the resistance modulation of n-CdO/n-SnO2 heterojunctions and the doping effect of Cd2+ ions.