**4.4 Electrodeposition method**

Electrodeposition (**Figure 9**) is a flexible low-cost method of fabrication of films. The principles of the electrodeposition process are based on principles of electrochemical phenomena associated with the reduction or deposition of electroactive and accompanying species on the cathode surface. H. Wang et al. [11] have elaborated TiO2 nanotube arrays by the combination of the electrodeposition method and the anodic aluminum oxide (AAO) templating method. A three-electrode potentiostatic system with a saturated calomel electrode (SCE) as a reference electrode and a platinum plate as a counter electrode was used for the electrodeposition method at room temperature. The potential used for the deposition is −0.8, −1.0 V in the electrolyte solution of 0.1 M TiCl3. The pH was maintained at 2.0 by adding a few drops of 2 M Na2CO3. After the deposition, the nanotubes in the AAO template were rinsed with double distilled water (DDW), then dried in air at room temperature and finally the samples were heated at 500°C for 2 h under N2 atmosphere.

## **4.5 Sol-gel method**

The sol–gel technique (**Figure 10**) is a wet low-temperature method that involves the formation of an inorganic colloidal suspension (sol) and gelation of the sol in a continuous liquid phase (gel) to form a three-dimensional network structure. J. Ben Naceur et al. [12] have elaborated TiO2 on ITO by sol–gel technique. To obtain stable solution, J. Ben Naceur have used 1 mol tetrabutyl-orthotitanate [Ti(OCH2CH2CH2CH3)4], 1 mol H2O, 4 mol butanol [CH3-(CH2)3-OH], and 3 mol acetic acid [CH3COOH]. The solution was stirred for 1 h at room temperature, and then a gel film was formed on ITO glass substrate.

**Figure 9.** *Schematic of the electrodeposition method.*

*Titanium Dioxide Thin Films for Environmental Applications DOI: http://dx.doi.org/10.5772/intechopen.99726*

**Figure 10.** *Schematic of the sol–gel method.*
