Oxygen Vacancy-Mediated Acetone Sensing of p-Type BiFeO 3 Nanoparticles

Bismuth ferrite (BiFeO 3, BFO) is a p-type multiferroic oxide with tunable defect chemistry, offering significant potential for gas sensing applications. Here, we report a cost-effective synthesis procedure of BFO nanoparticles via a hydrazine-assisted sonochemical synthesis method, which yields predominantly phase-pure perovskite BFO (>90%) with minor Bi 2 Fe 4 O 9 impurities. TEM analysis revealed an average particle size distribution of ∼80 nm; however, acetone sensing was strong and reproducible, which indicates that the collective nanoparticle ensemble governs performance. XPS analysis confirmed that iron is exclusively present in the Fe 3+ oxidation state and revealed a high concentration of surface oxygen vacancies. These vacancies act as active adsorption sites and facilitate the formation of reactive oxygen ions, driving the p-type response to acetone at concentrations as low as 1 ppm. The sensors demonstrated high sensitivity, rapid response and recovery, excellent selectivity over different kinds of interfering gases, and stable operation. These results underscore the crucial role of defect engineering and cost-effective synthesis in enabling efficient BFO-based acetone sensors for breath analysis and environmental monitoring.