Sensing mechanisms of hierarchical bismuth-doped antimony tungstate microspheres for CO2 detection at ambient temperatures

Bismuth-doped antimony tungstate (Bi-doped Sb 2 WO 6 ) microspheres were synthesized via a novel hydrothermal synthesis approach. These microspheres were then used as active layers in gas sensors for the detection of carbon dioxide (CO 2 ), a significant greenhouse gas and a critical parameter for evaluating air quality. The incorporation of bismuth significantly enhances the gas-sensing performance of the Sb 2 WO 6 microspheres, with the 4% Bi-doped sensing active layer achieving a remarkable response value of 15 when exposed to 200 ppm of CO 2 , outperforming the undoped Sb 2 WO 6 . Furthermore, the selectivity of the 4%Bi-Sb 2 WO 6 sensor toward CO 2 gas was enhanced relative to the Sb 2 WO 6 sensor. The fundamental mechanisms of gas sensing and the factors contributing to the improved CO 2 response of 4%Bi-Sb 2 WO 6 microspheres were investigated using density functional theory. Bi-doped Sb 2 WO 6 materials exhibit significant advantages in gas-sensing applications, including improved conductivity, enhanced gas adsorption capacity, increased reaction rates, good chemical stability, excellent selectivity, and the ability to adjust electron density. These characteristics enable Bi-doped Sb 2 WO 6 to demonstrate higher sensitivity and rapid response capabilities in gas sensors, making it suitable for practical applications. Graphical abstract