Bionic molybdenum oxide tube rich in oxygen vacancies synthesized by wheat straw template for high response and selective detection of mustard gas analogue

The development of MoO 3 -based sensors for rapid and sensitive detection of chemical warfare agent analogues (2-chloroethyl ethyl sulfide, 2-CEES) remains a great challenging due to the lack of specific report. Herein, discarded wheat straw (WS) was selected as self-sacrificial template. Through simple impregnation with ammonium molybdate solution followed by pyrolysis at 550   o C in air atmosphere, the 550   o C calcined MoO 3 (labeled as MoO 3 -550) biomimetic tubes formed by nanosheet cross-linking were successfully obtained. It exhibits three-level mesoporous distribution, relatively narrow bandgap and large specific surface area. The presence of low valence Mo(V) facilitates the formation of abundant oxygen vacancy (V O ) defects. The synergistic effect of these structural advantages promotes the rapid gas molecule migration and increases the content of reactive oxygen species at the surface. Consequently, the as-prepared MoO 3 semiconductor achieves rapid and selective detection of 2-CEES vapor at relatively low power consumption for the first time. At a low operating temperature of 133   o C, the MoO 3 -550 sensor exhibits a response value of 72.5 to 50 ppm 2-CEES vapor, which is 3.5 times higher than 650   o C calcined MoO 3 (labeled as MoO 3 -650) and 2.5 times higher than template-free MoO 3 (labeled as MoO 3 -TF). This performance also surpasses all previously reported resistive 2-CEES sensors. It also exhibits fast response rate, ppb level detection limit, reversible reproducibility and good stability. Furthermore, multiple techniques were employed to analyze its sensing mechanism toward trace amounts of 2-CEES.