Synthesis of high photocatalytic TiO2 by titanium-oxo-cluster for degradation of tetracycline in water

Tetracycline (TC) is a widely used antibiotic known for its significant antibacterial effects. However, its insufficient metabolism in living organisms and the accumulation of its residues have caused serious impacts on water sources and ecosystems. Photocatalytic technology, favored for its environmentally friendly, efficient, and non-polluting properties, has been applied to degrade TC. In this study, titanium dioxide nanoparticles (T6 and T32) were synthesized using titanium-oxo-clusters (Ti₆O₆ and Ti₃₂O₁₆) as the titanium source via a simple solvothermal method. Visible light degradation experiments revealed that the degradation rates of TC exceeded 92%, significantly outperforming commercial P25 (70%) and pure anatase TiO₂ (68%). Characterization by BET and XRD showed that the synthesized materials exhibited high specific surface areas (T6: 218 m²/g, T32: 207 m²/g) and good crystallinity. The surface complexes formed between the materials and TC enhanced the materials’ responsiveness to visible light (by broadening the absorption edge to 420 nm), playing a key role in the degradation process. Free radical trapping experiments and electron paramagnetic resonance (EPR) results indicated that ·O₂⁻, ¹O₂, and h⁺ were the primary reactive species involved in the degradation mechanism. Based on these findings, we propose a plausible degradation mechanism for the material. This study demonstrates that using titanium-oxo-clusters as a novel titanium source for TiO₂ synthesis can achieve highly efficient degradation of TC under visible light, offering innovative prospects for the development of future photocatalytic materials.