Nitrogen-doped mesoporous nanohybrids of TiO2nanoparticles and HTiNbO5nanosheets with a high visible-light photocatalytic activity and a good biocompatibility

Abstract

Nitrogen-doped mesoporous nanohybrids of TiO₂ nanoparticles and HTiNbO₅ nanosheets have been successfully synthesized by first exfoliating layered HTiNbO₅ in tetrabutylammonium hydroxide (TBAOH) to obtain HTiNbO₅ nanosheets, then reassembling with TiO₂ colloids and finally heating with urea in air at 450 °C. The resulting samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED), X-ray photoelectron spectroscopy (XPS), UV-vis spectroscopy, laser Raman spectroscopy (LRS) and N₂ adsorption–desorption measurements. It was found that the TiO₂ nanoparticles existed in the anatase phase and the titanoniobate nanosheets were still maintained after nitrogen doping. The obtained nitrogen-doped nanohybrids showed a greatly expanded surface area with a mesoporous structure and the doped nitrogen atoms were located in the interstitial sites of TiO₂, giving rise to the visible light response. The catalytic activities of the obtained samples were evaluated by the photodegradation of rhodamine B (RhB) solution under visible light irradiation. The obtained N-doped nanohybrid had a higher activity than N-doped HTiNbO₅ nanosheets and N-doped TiO₂, indicating the synergetic effect of TiO₂ nanoparticles and HTiNbO₅ nanosheets. The dye molecules were mainly degraded to aliphatic organic compounds and mostly further mineralized to CO₂ and/or CO, rather than being simply decolorized. In addition, the cell viability results of the HepG2 cells showed that the as-prepared sample had a good biocompatibility.