Preparation of Fe3+ Doped High-Ordered TiO2 Nanotubes Arrays with Visible Photocatalytic Activities

In this paper, the Fe3+ doped rutile phase TiO2 nanotubes arrays (NTAs) were prepared in a low temperature water-assistant crystallization method. It is noteworthy that the Fe3+ doping hardly hinders either the crystallization of rutile TiO2 NTAs or the highly-ordered nanotubular morphologies. Moreover, Fe3+ did not form other compound impurities, which indicated that Fe3+ substitute Ti4+ into the lattice of TiO2. With the introduction of Fe3+, the light absorption range of TiO2 NTAs extends from the ultraviolet band to the visible light range. Photocatalytic testing results indicate that Fe3+ doped TiO2 NTAs can effectively improve the degradation rate of methyl orange aqueous solution in visible light, and the TiO2 NTAs with 0.2 mol/L Fe3+ doping exhibits the highest photocatalytic degradation efficiency.

Effect of Deposition Time of Mn on Photoelectrochemical Properties of Mn/TiO2 Nanotubes

Coupling of TiO2 nanotube arrays (NTAs) with narrow band gap materials has been a promising strategy to extend the absorption of TiO2 into visible light region. In this work, the fabrication of manganese doped TiO2 nanotube arrays (Mn/TiO2 NTAs) was carried out by an electrodeposition method. The deposition time of Mn onto TiO2 NTAs which was varied in the range of 1-5 minutes was found to play an important role in controlling the formation and distribution of Mn nanoparticles onto TiO2 NTAs. The films were characterized by field emission scanning electron microscopy (FESEM), X-ray diffractometry (XRD), energy dispersive X-ray spectroscopy (EDX) and UV–vis diffuse reflectance spectroscopy to determine their morphology, crystalline structure, and optical properties of the samples. The results from FESEM showed that Mn nanoparticles were found to grow larger and cause blockage to the mouth of the nanotubes with prolongs deposition time. On the other hand, Mn/TiO2 NTAs synthesized with shorter deposition time exhibits significant enhancements in the optical absorption and photocurrent density. In particular, the Mn/TiO2 NTAs produced at 1minute deposition time exhibited the highest photocurrent density compared to the others. The uniform distribution and quantity of the Mn could be the reason for this performance, therefore, more light was absorbed and generating more electron-hole pairs then giving the highest photocurrent.

Study on the Photocathodic Protection of Q235 Steel by CdIn2S4 Sensitized TiO2 Composite in Splash Zone

In this work, the photo-catalytic activity of TiO2 is considerably enhanced via sensitization with CdIn2S4, and its application for protecting Q235 from corrosion in splash zones is examined. TiO2 nanotube arrays (NTAs) are prepared on a flat Ti substrate via two-step anodization. CdIn2S4 is deposited on the surface of TiO2 NTAs by hydrothermal reaction. TiO2 NTAs with enormous specific surface areas and large-diameter hollow nanostructures are found to benefit the immobilization of CdIn2S4. As a narrow band gap semiconductor, CdIn2S4 is able to extend the light absorption range of TiO2, and the construction of an n–n type hetero-junction accelerates the separation of carriers. Strong solar light, which accelerates the corrosion of Q235 in the splash zone area, is converted into the necessary condition for protecting Q235 from corrosion. In this work, TiO2 is sensitized with MoS2 microspheres (MoS2/TiO2 nanocomposites), which were prepared on a flat Ti substrate via a two-step anodization and hydrothermal method, sequentially.