Enhancing humidity sensitivity properties through RE (Er, La, and Sm) dopants in TiO₂ nanofiber composites

Undoped and rare earth (RE) elements (Er, La, and Sm)-doped TiO₂ nanofiber composites were prepared by electrospinning, followed by calcination at 600 °C. X-ray diffraction (XRD), scanning electron microscopy (SEM), and BET surface area analysis were used for the microstructural characterization of RE-doped TiO₂ nanofibers. In the XRD analysis, both the pure TiO₂ and RE-doped TiO₂ nanofiber composites exhibited diffraction peaks corresponding to the anatase and rutile phases. SEM analysis revealed the presence of uniform and continuous nanofibers in both pure TiO₂ and RE-doped TiO₂ samples, highlighting their one-dimensional morphology. The addition of RE elements leads to slight increases in electrical permittivity and minor decreases in electrical resistivity, which are attributed to space charge polarization and variations in the crystallite size. The humidity-sensing performance of these materials was examined, revealing their responsiveness to changes in relative humidity levels. RE-doped TiO₂ nanofibers exhibited a more improved humidity response compared to pure TiO₂ nanofibers.