Cu/N co-doped TiO 2 nanopowder was prepared with a facile sol–gel method. In the absence of stabilizing agents, the co-doped nanopowder with nanoscaled particle sizes was obtained. Doping didn’t change the anatase crystal structure of TiO 2 . Cuprite Cu 2 Cl(OH) 3 formed in the co-doped nanopowder. Based on ultraviolet–visible (UV–vis) spectroscopy and X-ray photoelectron spectroscopy (XPS) data, the mechanisms of significantly improved photocatalytic activity of the co-doped nanopowder were discussed. The antibacterial evaluation and cytotoxicity test suggested the nanopowder inhibited bacteria significantly under visible light and had ultralow cytotoxicity. This work provided a promising antibacterial agent with potential biomedical applications.
Graphical abstract
Photocatalytic degradation performance of oxytetracycline (OTC) was investigated in aqueous solution using Fe2O3–TiO2 nanopowders under UV and visible light, respectively. Compare with pure TiO2, the Fe2O3–TiO2
nanopowder had improved photocatalytic activity under visible light, while had a bit decrease under UV light. Photoluminescence (PL) spectrum measurement, ·OH radical test and trapping experiments were carried out to investigate the photocatalytic mechanism. Under UV light, photogenerated
electrons–holes can transfer from TiO2 to the conduction band and valence band of Fe2O3, respectively, and further participated in the degradation of OTC, thus both O2·− and holes are the main active species in this case. Under
visible light, Fe2O3 was activated and yield charge carriers, then the photogenerated electrons immigrated to the trapping site of TiO2, the photogenerated holes accumulate in the valence band (VB) of Fe2O3 was the major active species
reacted with OTC.
Wenlan Wang,Qingkun Shang,Wei Zheng,Hui Yu,Xuejiao Feng,Zhidan Wang,Yabin Zhang,Guoqiang Li
A novel near-infrared antibacterial material, Er3+-Yb3+-Fe3+ tridoped TiO2 nanopowder, was synthesized and applied to kill Aeromonas hydrophia with a maximal bactericidal rate of 65% in 90 min under 980 nm laser irradiation. However, Fe3+-TiO2 or Er3+-Yb3+-TiO2 nanopowders obtained under the same conditions barely could kill Aeromonas hydrophia. The initial energy applied in the photocatalysis antibacterial process is supplied by the upconversion emission of Er3+ and Yb3+ and the codoping of Fe3+, which has intensified the light absorption intensity and enlarged the absorption range. The analyses of phase structure and the optical properties including XRD, UV−vis diffuse reflectance spectra, and upconversion photoluminescence spectra of Er3+-Yb3+-Fe3+ tridoped TiO2 nanopowder have been performed in detail to reveal the complex energy transfer and change mechanism. According to our experimental results, the mechanism has been demonstrated involving the upconversion emission, multistep excitation by means of intermediate energy level, capture and transfer electrons of Fe3+, and so on. The photocatalystic antibacterial function of Er3+-Yb3+-Fe3+-TiO2 under near-infrared instead of ultraviolet light is also reported. Because of the strong penetrability of near-infrared, this kind of material may be used in photodynamic therapy (PDT) to kill bacteria or tumors directly.
The degradation behavior of oxytetracycline (OTC) in aqueous solution using Fe2O3–TiO2 nanopowders (Fe2O3–TiO2 NPs) as photocatalysts under UV/visible light was investigated in this paper. Fe2O3–TiO2 NPs photocatalysts synthesized using co-precipitation were characterized by XRD, TEM, FT-IR and UV-vis DRS. Fe2O3–TiO2 NPs with 45 wt% Fe2O3 exhibited higher photocatalytic activity than others. The photocatalytic degradation of OTC shows a maximum efficiency at pH = 5.5 under both UV/visible light due to the surface adsorption. The intermediate products during the photocatalytic degradation of OTC were detected by LC-MS/TOF. Seven main intermediates were formed, and their evolution was discussed. On the basis of the evidence oxidative intermediate formation and a detailed degradation path way of OTC by 45 Fe2O3–TiO2 NPs are proposed.
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