Ultrasensitive triethylamine gas sensors with ZnSe nanospheres/nest-like Cr-doped MoO3

Developing high-sensitivity TEA sensors has extremely important significance for human health. Design of three-dimensional (3D) nanostructures assembled from one-dimensional nanomaterials can effectively improve sensing performance. In this work, a nest-like structure assembled by Cr-doped MoO3 (Cr-MoO3) nanorods with relatively higher specific surface area was prepared. In order to improve the sensing performance, Cr-MoO3 skeleton was combined with ZnSe nanospheres of different mass ratios as sensing materials (ZnSe/Cr-MoO3), and the successful construction of the heterojunction structure was supported by various spectroscopies and charge density calculation. The prepared composite with an optimal moiety ratio showed very high response values of 371 and 1301 for 10 ppm and 50 ppm for TEA at 200 °C, respectively. Simultaneously, the composite sensor also exhibited a low detection limit (1.7 ppb). The improvement of the sensing performance of ZnSe/Cr-MoO3 was attributed to the formation of oxygen vacancies induced by Cr doping, the 3D nest-like structure provided an efficient network for charge transport/collection and the n-n heterojunctions between Cr-MoO3 nanorods and ZnSe nanospheres. The simulation analysis based on density functional theory (DFT) calculations indicated that the heterojunctions could effectively enhance the adsorption energy of TEA and the more charges transferring from TEA to the Cr-MoO3 nanorods. Triethylamine (TEA) is an organic base and has strong alkalinity and water solubility. TEA has diverse applications in chemical, pharmaceutical and agricultural fields. In addition, TEA is also a naturally occurring substance released during the decomposition of fish and shellfish. It serves as an indicator for assessing the freshness of marine fish. However, TEA poses health risks to humans when there is prolonged exposure through contact or inhalation. The Occupational Safety and Health Administration (OSHA) established the exposure limit for TEA, which is set at 10 ppm. Therefore, developing efficient and sensitive TEA gas sensors has important significance and value.