Investigation of growth mechanism for highly oriented TiO2 nanorods: the role of reaction time and annealing temperature

Abstract

Titanium dioxide (TiO 2) is a versatile and inexpensive material for extended applicability in several scientific and technological fields including photo-catalysis for industrial waste treatment, energy harvesting, and hydrogen production. In this work, we report the synthesis of TiO 2 thin film using hydrothermal method and investigations on the influence of reaction time and annealing temperature on growth mechanism of the TiO 2 nanorods. The synthesized TiO 2 films were studied by using UV-visible spectroscopy, Raman spectroscopy, X-ray diffraction (XRD), scanning electron microscope and energy-dispersive X-ray spectroscopy (EDS). The XRD and Raman measurements revealed the formation of defect free and pure tetragonal TiO 2 rutile phase. The TiO 2 thin films show absorption band edge at around 420 nm in the UVvisible spectrum and exhibit direct band gap value of 2.9 eV. The TiO 2 nanorods are demonstrated to grow randomly on the FTO substrate with changing reaction times but grow uniformly in a flower-like pattern with increasing annealing temperature. Investigation of the field emission properties of TiO 2 thin films (tested as field-emitter array) estimates the turn-on and threshold field at 4.06 and 7.06 V/µm at 10 and 100 µA/cm 2 , respectively.

Hydrothermal Growth of ZnO Nanorods for Use in Dye-Sensitized Solar Cells

“…The optical absorption spectra of all the samples synthesized by the hydrothermal route at different reaction times were found in the range of 375–395 nm and are evident in Figure a. The shift in the band edge toward a longer wavelength (red-shift) with increasing reaction times was attributed to the electronic transition from the valence band to the conduction band. , The direct optical band gap of the ZNR samples was estimated by the Tauc-plot relation: (α h ν) 2 = B ( h ν – E g ), where α is the absorption coefficient, h is Planck’s constant (6.626 × 10 –34 m 2 ·kg/s), ν is the photon frequency, and E g is the optical band gap energy. The value of E g was estimated from the plot between h ν at the abscissa and (α h ν) 2 at the ordinate (Figure b).…”

Role of pH in the Hydrothermal Synthesis of TiO2 Nanorod Photocatalysts

“…So the initial stage of the growth process was limited by the premature termination of the growth surface, but with equal ratio of HCl : H 2 O, the regularly shaped particles were transformed to the onset of nano‐rod bunch morphology in one direction and further to a bunch of nanorods anchoring on the substrate. In fact, the TiO2 nanorods clearly look like a bunch of flowers in all directions which from a point on the substrate [26c,27] …”

Interfacial band offset engineering with barium-doping towards enhanced performance of all inorganic CsPbI2Br perovskite solar cells

“…TiCl 4 treatment was carried from an aqueous TiCl 4 solution followed by sintering at 450 1C for 30 min. 35,36…”