Unveiling the synergistic effects of hydrogen annealing on CeO2 nanofibers for highly sensitive acetone gas detection: Role of Ce3+ ions and oxygen vacancies

Abstract

Acetone, a toxic and widespread gas, necessitates continuous monitoring. Cerium oxide (CeO2), an n-type rare earth semiconductor metal oxide with unique oxygen storage capabilities, has garnered significant interest in gas detection. In this study, hydrogenated CeO2 nanofibers were obtained by electrospinning and subsequent annealing in hydrogen gas. XRD results reveal that hydrogen annealing does not alter the original cubic fluorite phase structures of CeO2. SEM results also indicate that hydrogen annealing did not alter the nanofiber structures of CeO2. XPS analysis confirms the reduction of Ce4+ to Ce3+ ions, resulting in an increased concentration of Ce3+ ions and oxygen vacancies with increasing annealing temperature. The hydrogenated CeO2 sensor (CeO2-H-680) exhibits a response of 5.45 to 100 ppm acetone at 200 ℃, 4.2 times higher than that of the pure CeO2 sensor, as well as good selectivity, repeatability, and long-term stability. The improved gas-sensing performance achieved through hydrogen annealing is attributed to the increased concentration of Ce3+ ions and oxygen vacancies. Overall, hydrogen annealing of metal oxides effectively regulates oxygen vacancies for enhanced gas sensing performance.