An Acad Bras Cienc. 2023 Aug 11;95(2):e20201164. doi: 10.1590/0001-3765202320201164. eCollection 2023.
The TiO2 nanotube arrays were prepared by anodization, and the crystal structure was changed by calcination at different temperatures. The photocatalytic performance of the samples was measured by the degradation of rhodamine B under visible light. The TiO2 nanotubes calcined at 600 °C showed higher photocatalytic activity than other samples. The prepared catalyst is characterized by a variety of techniques, including X-ray diffraction, scanning electron microscopy, ultraviolet-visible diffuse reflectance spectroscopy, Raman, photoluminescence spectroscopy and electrochemical testing. The reasons for improving the catalytic activity were studied from the aspects of crystal structure, surface morphology, and photoelectric properties, and the catalytic mechanism was studied. The results show that the TiO2 nanotubes calcined at 600°C contain two phases of anatase and rutile. Compared with pure phase TiO2, the charge transfer resistance is reduced and the electron-hole reorganization is well suppressed. In addition, it affects the band structure and improves the absorption of visible light. At the same time, studies have found that the main active substances in the catalytic process are h+ and •OH.