Initial reactant controlled synthesis of double layered TiO2 nanostructures and characterization of its spectra of absorption and photoluminescence

•Double layered TiO2 nanostructures were synthesized by a hydrothermal method.•The process of synthesizing only at different initial reactant concentrations.•The synthesized TiO2 nanostructures exhibit good crystal quality.•The double layered TiO2 nanostructures showed excellent optical properties.

Double layered titanium dioxide (TiO2) nanostructures were synthesized on fluorine-doped tin oxide (FTO) substrates using a low-cost and convenient hydrothermal method. The prepared TiO2 nanostructures were characterized by scanning electron microscope (SEM) and X-ray diffraction (XRD). The SEM images showed that the double layered TiO2 nanostructure composed of one layer of TiO2 nanorods film on FTO and one layer of TiO2 nanoflowers on the TiO2 nanorods film. The results of XRD indicated that the prepared TiO2 nanostructures were rutile TiO2. The band gap of the prepared TiO2 nanostructures was calculated by ultraviolet–visible (UV–vis) absorption spectrum. Optical properties of the samples were investigated by photoluminescence (PL) spectroscopy. The results indicated that all of the prepared samples had the same luminescence center. And the luminescence intensity of double layered TiO2 increased with increasing the excitation wavelength.