Development of clean and renewable energy sources is very important issue to tackle the environmental problems. The process of photocatalytic water splitting for producing hydrogen under sun light radiation is one of the most valuable techniques to create renewable energy sources. Among the various semiconductors, due to special properties such as high stability and environmental friendly, titanium dioxide has required properties for practical applications and its use in the industry. However, due to being active in the range of UV light and low mobility of electrons, it is limited for large-scale application. By doping titanium dioxide with various elements or combination with other semiconductors, this problem can be solved. In this project, using simple and easy methods this work was done. In the first step, by in-situ anodizing Cr doping of TiO 2 with concentration of (0.005M), CrTiO 2 nanotubes were prepared. In the next step by chemical bath deposition, coating of Fe 2 O 3 -WO 3 and CuO-WO 3 with different molar ratios was prepared on the surface of CrTiO 2 nanotubes. The morphology, structure and optical properties of prepared samples was investigated by FE-SEM, XRD, EDX and UV-visible techniques. The presence of chromium, iron, tungsten and copper in nanotubes and reduce the band gap using this techniques was confirmed. Then the effect of quantity and ratio of these compounds on the photoelectrocatalytic activity of prepared samples was evaluated by LSV and CA techniques. The results showed that the photoelectrocatalytic performance of CrTiO 2 nanotubes modified with both groups, compared with pure TiO 2 and bare CrTiO 2 , increased considerably. In iron-tungsten group CT 6 photoanode revealed highest photocurrent, maximum hydrogen production, excellent stability and reusability and it was selected as the optimum sample. In copper-tungsten group results indicated lower photoelectrocatalytic performance that because of more coated nanotubes with copper particles for 30 minutes, but this performance has been improved with decreasing deposition time. In this group CT 12 photoanode was chosen optimum samples with the highest photocurrent, maximum hydrogen production, good stability. In general, CrTiO 2 nanotubes modified with Fe 2 O 3 -WO 3 revealed more photoelectrocatalytic performance compared to CrTiO 2 nanotubes modified with CuO-WO 3 . This project provided a facile way with high efficiency for the synthesis of modified titanium dioxide nanotubes for application in solar energy conversion. New photoanodes have more potential for implementation on the large scale and industry to generate hydrogen as a clean energy due to the excellent photocatalytic activity and stability.
