Titanium dioxide nanotubes (TiO2) have many applications and are considered as the most important optical catalysts due to their properties such as optimal stability in different environments as well as special photocatalytic properties. Due to the wide band gap of TiO2, which is active in the ultraviolet range, it has not yet been used as a high-performance nanocatalyst, so one of the goals of improving the performance of TiO2 nanocatalyst is transmit it from the ultraviolet to visible wavelength range. To achieve such a goal, it is possible to dope the structure of TiO2 with other elements or modify the surface of TiO2 nanocatalyst with semiconductors. In this study, titanium dioxide nanotubes containing sulfur (STiO2) were prepared by single step anodizing method (in 12 mM K2S2O5 solution and DMSO solvent at room temperature for 8 hours at 40 volts) and then at different times (1 to 4 hours) by immersion method. (In 0.01 M tris buffer solution and 0.26 M dopamine solution at pH = 8.6) Dopamine was polymerized on STiO2 nanotubes. Using FE-SEM, XRD, EDX and UV-Vis methods, surface morphology, structure, dispersion of elements on the surface of nanotubes and optical properties were investigated. These studies confirmed the formation of nanotubes, the presence of sulfur and polydopamine on the nanotubes, as well as the reduction of the TiO2 band gap from 3.25 to 2.59 electron volts. Photocatalytic activity was eva‎luated using LSV, CA and OCP methods. Examination of the photocatalytic properties of these STiO2 nanotubes showed that the photocatalytic properties were improved by coating with polydopamine and samples S1 and S3 (during 1 and 3 hours of polydopamine immersion polymerization) was selected as the sample and optimal time due to better response to most of the mentioned tests. By modifying the surface of STiO2 nanotubes at 600 mV, the current density increased from 28.71 µA/cm2 to 174.83 µA/cm2.

محمد ديناري، محمد محسن مومني هامانه

غلامحسين محمدنژاد

اسماعيل حيدري، عليرضا نجفي