Gas sensors based on Co3O4/TiO2 core-shell nanofibers prepared by coaxial electrospinning for breath marker acetone detection

Gas sensors play an important role in environmental detection and exhaled breath biomarker detection. In this paper, Co3O4/TiO2 core-shell NFs were synthesized by coaxial electrostatic spinning method. The morphology, structure and composition of the composites were analyzed by SEM, TEM, EDS, XRD and XPS. The results of conventional static gas sensitivity performance tests showed that the Co3O4/TiO2 sensors exhibited a P-type response with excellent sensing performance to acetone. The higher response values and better selectivity of Co3O4/TiO2 sensors for acetone were observed compared to Co3O4 NFS and TiO2 NFS sensors, and the shortcomings that cannot be recovered from TiO2 NFS have also been significantly improved. In addition, the breath simulation experiments showed that the Co3O4/TiO2 sensors have a lower acetone detection limit down to 500 ppb. The initial resistance of the Co3O4/TiO2 sensor does not change significantly with relative humidity increasing, and the response value fluctuates by 1.5% at 300 °C. The enhanced acetone sensing performance of Co3O4/TiO2 is ascribed to the heterojunction and porous structure which result in more adsorbed active sites on the material surface. With the advantages of low detection limit and high anti-humidity, Co3O4/TiO2 gas sensors are expected to become a potential candidate for the detection of acetone in exhaled gas of patients with diabetes in clinical non-invasive testing.