Characteristics of N-doped TiO2 nanotube arrays by N2-plasma for visible light-driven photocatalysis

N-doped TiO2 nanotube arrays were prepared by electrochemical anode oxidation of Ti foil followed by treatment with N2-plasma and subsequent annealed under Ar atmosphere. The morphologies, composition and optical properties of N-doped TiO2 nanotube arrays were characterized using field-emission scanning electron microscope (FE-SEM), transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction spectrometer (XRD), Photoluminescence (PL) and UV–vis diffusion reflection spectroscopy (UV–vis DRS). Methylene blue (MB) solution was utilized as the degradation model to evaluate the photocatalytic activity of the samples under visible light irradiation. The results suggested N2-plasma treatment created doping of nitrogen onto the surface of photoelectrodes successfully and the N-doped TiO2 nanotube arrays display a significantly enhancement of the photocatalytic activity comparing with the pure TiO2 nanotube arrays under the visible light irradiation.

► A new pathway is provided to prepare N-doped TiO2 nanotube arrays using N2-plasma treatment.
► N2-plasma treatment did not wreck the structure of nanotube arrays.
► Nitrogen doping promoted the phase transition to rutile phase at low annealing temperatures
► Nitrogen doping narrow band gap of TiO2 and improve the photocatalytic activity of samples.