Enhanced interfacial charge transfer in WO3-Bi2WO6 heterostructures: Toward trace detection of mustard gas simulant

Developing reliable and portable sensors for detection of highly toxic mustard gas is extremely important for public security. However, gas sensors based on pristine metal oxide semiconductors often suffer from high working temperature, inferior response, and inadequate detection limit owing to their poor intrinsic conductivity and weak adsorption toward target gases, thereby hindering their wide application. Herein, hierarchical WO 3 -Bi 2 WO 6 heterostructures were fabricated as sensing materials to comprehensively improve their sensing properties to 2-chloroethyl ethyl sulfide (2-CEES, a mustard gas simulant). The optimized sensor based on WO 3 -Bi 2 WO 6 -2 displayed short response time of 1.4 s and high sensing response (R a /R g  = 63) to 50 ppm 2-CEES at 133 °C, together with an ultra-low detection limit of 10 ppb. The improvement of WO 3 -Bi 2 WO 6 -2 in sensing properties are synergistically attributed to the amount of heterojunction and surface adsorption sites, which were proved by DFT calculations and a series of characterizations. This work might pave the way for further developing heterostructure-based sensors for 2-CEES detection with superior sensing properties.