Probing the effect of molar concentration on TiO₂ nanorod/nanoflower films toward enhanced field electron emission properties

In this work, we report on the synthesis of rutile-TiO₂ nanostructures for field electron emission studies using a simple one-step hydrothermal method at various TiCl₄ molar concentrations. The formation of the pure and tetragonal rutile phase of TiO₂ films has been confirmed by X-ray diffraction and Raman spectroscopy. The scanning electron microscopy analysis shows TiO₂ has nanorods and nanoflower-like morphology with sharp petals. UV–Visible spectroscopy study exhibited broad absorption in the visible range with a band gap energy ranging from 2.32 to 3.01 eV over the entire range of TiCl₄ molar concentration varied. A possible crystal growth mechanism and electron emission properties of TiO₂ films are also discussed. At 0.6 M molar concentration of TiCl₄, rutile-TiO₂ film exhibited excellent field emission properties, including a low turn-on field of 1.11 V/µm for 10 µA/cm², a maximum current density of 331.91 µA/cm² at the applied bias of 3.44 V/μm, and superior current stability for three hours at a preset current of 1.08 µA. The results revealed that the rutile-TiO₂ nanostructures can be used for various practical applications such as optoelectronics, biomedical devices, and supercapacitors.