Constructing stable NiO/N-doped TiO2 nanotubes photocatalyst with enhanced visible-light photocatalytic activity

N-doped TiO2 nanotube arrays modified with NiO (denoted NiO/N-TNTs) were successfully prepared by a facile impregnation-calcinations-cycle technique. As-prepared nanocomposites were characterized by field emission scanning electron microscopy, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, UV-vis diffuse reflectance spectroscopy and photocurrent tests. The photocatalytic activities of the as-prepared samples were measured by the degradation of Rhodamine B aqueous solutions under visible-light irradiation (lambda > 420 nm). The results indicated the nitrogen was doped into the lattice and the NiO nanoparticles were deposited into the pore of the photocatalysts. N-doping narrows the band gap and NiO modification accelerates the separation of photo-induced electron-hole pairs. Consequently, NiO/N-TNTs photocatalyst exhibited a higher photocatalytic activity than pure TNTs, NiO/TNTs and N-doped TNTs photocatalysts. Interestingly, the NiO/N-TNTs photocatalyst possesses good stability. A possible mechanism on the NiO/N-TNTs photocatalytic activities was suggested. Such a photocatalyst should be potential for organic pollutant removal in photocatalytic system.