Preparation of porous nitrogen-doped titanium dioxide microspheres and a study of their photocatalytic, antibacterial and electrochemical activities

Porous N-doped TiO2 microspheres were prepared for the first time via plasma technique. The sample exhibited better photocatalytic activity, photoinduced inactivation activity and better electrochemical activity than those of TiO2 microspheres and P25. [Display omitted] ► Porous N-doped TiO2 microspheres were prepared via nitrogen plasma technique. ► Plasma treatment did not affect the porous structure of the TiO2 microspheres. ► With the plasma treatment, the N contents in the samples increased. ► Their photocatalytic, antibacterial and electrochemical activities were studied. Nitrogen-doped titanium dioxide (N-doped TiO2) microspheres with porous structure were prepared via the nitrogen-assisted glow discharge plasma technique at room temperature for the first time. The samples were characterized by X-ray diffraction, scanning electron microscopy, nitrogen adsorption–desorption measurement, UV–Vis diffuse reflectance spectra, photoluminescence spectroscopy and X-ray photoelectron spectroscopy. The results indicated that the plasma treatment did not affect the porous structure of the TiO2 microspheres. With the plasma treatment, the N contents in the samples increased. During the photocatalytic degradation of methylene blue under simulative sunlight irradiation, the sample after plasma treatment for 60min (N-TiO2-60) exhibited higher photocatalytic activity than those of the TiO2 microspheres, P25 and other N-doped TiO2 microspheres. Furthermore, the N-TiO2-60 showed excellent antibacterial activities towards Escherichia coli under visible irradiation. These should be attributed to the enhancement of the visible light region absorption for TiO2 after N-doping. Electrochemical data demonstrated that the N-doping not only enhanced the electrochemical activity of TiO2, but also improved the reversibility of Li insertion/extraction reactions and the rate behavior of TiO2 during charge–discharge cycles.