Morphology-controlled synthesis of chromia–titania nanofibers via electrospinning followed by annealing

Titania (TiO2) fibers supporting chromia (Cr2O3) were prepared by forming TiO2 fibers via electrospinning, then immersing the as-prepared fibers in a chromium nitrate solution followed by annealing. The annealing process allowed for the formation of chromium oxide on the surface of the TiO2 fibers and for the development of porosity. The mean diameter of the prepared fiber samples ranged from 350 to 445 nm. Controlling the annealing temperature from 500 to 700 °C resulted in fiber morphologies ranging from partly to fully porous. Additionally, X-ray diffraction peak intensities corresponding to both TiO2 and Cr2O3, increased at higher annealing temperatures. Meanwhile, the Cr2O3 content of the TiO2 fibers was dependent on the concentration of the chromium nitrate solution. Elemental mapping was performed using scanning transmission electron microscopy (STEM) with energy-dispersive X-ray spectroscopy (EDS) to investigate the chemical composition inside the porous fibers. Chromium was relatively well distributed in the TiO2 fibers. The porous fibers produced using the method described in this paper have potential use in catalysts and gas sensors.