Cr doped WO3 nanofibers enriched with surface oxygen vacancies for highly sensitive detection of the 3-hydroxy-2-butanone biomarker

Listeria monocytogenes, a virulent food pathogenic microbe exhaling the biomarker 3-hydroxy-2-butanone (3H-2B), can cause human illnesses and even deaths. Conventional techniques for the detection of Listeria monocytogenes suffer from requiring either sophisticated techniques or complicated facilities. Herein, we report an advanced gas sensor to sensitively and selectively detect the 3H-2B biomarker for the real-time monitoring of Listeria monocytogenes. The sensors are built with surface-oxygen-vacancy enriched chromium (Cr) doped WO3 nanofibers (NFs), obtained via an optimized electrospinning process. The 3H-2B biomarker sensors have an optimum working temperature of 140 degrees C. Remarkably, the WO3 NFs with 2% Cr dopant exhibit excellent sensitivity (R-a/R-g = 71.8; 5 ppm 3H-2B; 140 degrees C), showing five-fold improvement compared with pristine WO3 NFs (R-a/R-g = 14.1). Moreover, the sensors are able to detect concentrations as low as 0.05 ppm 3H-2B (R-a/R-g = 2.1), and show miraculous selectivity and long-term stability. We mainly attribute the excellent sensing performance towards 3H-2B to Cr dopants modulating the electron depletion layer (EDL) via enriching surface oxygen vacancies. The unique structure of the Cr doped WO3 NFs also benefits the sensing performance. Our synthetic strategy and building of sensors for the detection of the 3H-2B biomarker provide new insight into the future development of portable and inexpensive devices for food pathogenic microbes.