Novel Sm-doped FeTiO3/WO3 Z-scheme heterojunction for efficient photo-Fenton degradation of tetracycline hydrochloride.

As an iron-based photocatalytic material, FeTiO3 has become an important semiconductor material due to its excellent stability and visible light absorption capabilities. However, the catalytic activity of pure FeTiO3 is notably hindered by the fast recombination of photogenerated charges and its insufficient oxidation strength. To address this, in this study, a novel Sm-doped FeTiO3/WO3 (SF/W) composite was synthesized using the sol-gel method. The doping of Sm effectively regulates the band structure of FeTiO3, significantly promoting the separation of carriers. At the same time, the Z-scheme heterojunction formed with WO3 further optimizes the charge transfer path, not only greatly improving the charge carrier separation efficiency but also significantly enhancing the redox capability of the photocatalyst. The density functional theory (DFT) calculation results show that the strong internal electric field (IEF) formed by SF/W composite provides an efficient transfer channel for photogenerated electrons, promoting the cyclical transformation of Fe2+/Fe3+ in the photo-Fenton process, thereby continuously generating more reactive species. Therefore, at the optimal doping ratio, the photo-Fenton degradation efficiency of the SF/W for Tetracycline hydrochloride (TCH) reaches 95.6 % within 20 min. Moreover, through Liquid Chromatograph Mass Spectrometer (LC-MS) and Toxicity Estimation Software Tool (T.E.S.T.) analysis led to the proposal of potential degradation pathways and an evaluation of the toxicity of the resulting products.