Perovskite-Structured BiFeO₃ Nanoparticles with Abundant Oxygen Vacancies for Selective n-Butanol Gas Sensing

N -butanol, a standard volatile organic compound (VOC) gas with toxicity and flammability, seriously endangers human life and health. It is imperative to achieve rapid and trace detection of n-butanol. Oxygen vacancies have been proven to be an essential factor for VOC gas adsorption at the surface of metal oxide semiconductor (MOS) gas sensors. In view of the above, BiFeO 3 (BFO) nanoparticles with abundant oxygen vacancies were prepared via simple sol–gel and annealing. Crystal structure, morphology, and compositions were systematically analyzed by a series of characterizations (XRD, SEM, HRTEM, EPR, and XPS). The response of the synthesized BFO-2 sensor reached 19.37 to 100 ppm n -butanol with a detection limit of 0.28 ppm at an optimal operating temperature of 280 °C. In addition, BFO-2 also has a fast response time, good stability and repeatability, and favorable selectivity to n -butanol. It is crucial to systematically explore the excellent selectivity of BFO sensors due to their abundant oxygen vacancies and large intrinsic crystal defects. Herein, adjusting the calcination temperature is one constructive strategy to tune the oxygen vacancy, which would prompt the gas sensing performance of BFO sensors to n -butanol.