Abstract
Abstract We prepared nano-zero-valent iron (nZVI) and N co-modified TiO2 (nZVI/N–TiO2) nanotube arrays as an enhanced visible-light photocatalyst. The TiO2 nanotube arrays were synthesized by electrochemical anodization of Ti foil in a two-electrode system. Amorphous TiO2 nanotube arrays were immersed in ammonia and then annealed to produce crystalline N-doped TiO2 (N–TiO2) nanotube arrays. nZVI spheres were directly deposited on the N–TiO2 nanotube arrays by borohydride reduction. The photocatalysts were characterized by field emission scanning electron microscopy (FESEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), UV–visible diffuse reflectance spectroscopy (UV–vis DRS), and electrochemical impedance spectroscopy (EIS). The environmental applicability and photocatalytic activity of the proposed nZVI/N–TiO2 nanotube arrays were tested by phenol degradation in an aqueous system under UV and visible light irradiation. The phenol degradation rate constants of each sample under visible light irradiation were in the following order: nZVI/N–TiO2 (kobs=0.006 min−1)>N–TiO2 (kobs=0.002 min−1) ⪢ nZVI/TiO2 (kobs=0.0003 min−1)>TiO2 (kobs=0.0001 min−1). This result can be attributed to the synergistic effect of the N–TiO2 nanotubes with lower energy band gap and the electron transfer from the conduction band (CB) of N–TiO2 to nZVI spheres highly-dispersed on the N–TiO2 for enhanced separation of photogenerated electrons and holes.
Published Version
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