TiO2 nanotube like structures on FTO substrate by dip coating method

TiO2 nanostructures have engrossed much attraction because of their exclusive properties such as low cost, non-toxicity, good stability and excellent optical and electrical properties. Many group has reported different synthesis techniques for different TiO2 nanostructures [1]. The building blocks of TiO2 nanomaterials such as nanotubes, nanowires, and nanorods have been reported for many applications in photocatalytic activities, water splitting, pigments, dye synthesized solar cells and even in third generation perovskite solar cells [2–4]. Here, we report TiO2 nanotube like structure prepared on FTO substrate. Earlier, researchers have fabricated TiO2 on glass substrate. However, the adhesion with glass is not well reported. FTO has been reportedly shows good adhesion with TiO2. Synthesis process plays crucial role in controlling structure and physical properties of materials. Among many physical and chemical routes, in this report we have synthesized sample using a simple and low temperature dip coating technique. It is well-known technique for growing nanorods and –tubes. The key advantage of this process is, it can be adapted for large volume and thickness of the films can be controlled with withdrawal time. The structure of the sample is characterized using X-ray diffraction (XRD) and atomic force microscopy (AFM). The X-ray diffraction of prepared sample shows dominating anatase phase in mixed anatase-rutile structure with P42/mnm space group. The average crystallite size calculated from Debye – Scherrer method is 58 nm. Atomic force microscopy is carried out for surface morphology of the sample and it shows the nanotubes like structures. The calculated average roughness is around 17 nm. For the optical study, sample is characterized with UV-Visible spectroscopy. The transmittance of the sample is ~70% at 900 nm incidence and optical energy band gap is calculated using tauc-plot. The calculated value of TiO2 is found to be ~2.8. TiO2 shows wide band gap which has potential applications in photocatalytic activity, photo electrochemical applications [5]. However, the key issue is wide band gap of TiO2 is highly sensitive to UV light, which is <5% of overall Energy spectrum. Tuning the band gap with ionic substitution and making composites accommodating it in nanostructures can open new energy application possibilities such as super capacitors and RRAM devices [6,7].