Enhanced Photocatalytic Activity of Perovskite-Type NaTaO₃ by Effective Nitrogen Doping

N-doped perovskite-type NaTaO₃ with cubic shape was synthesized by a facile hydrothermal method and nitridation treatment in the presence of ambient NH₃. The well-crystalline N-doped NaTaO₃ (N–NaTaO₃) products were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), field-emission scanning electron microscopy (SEM) and ultraviolet-visible diffuse reflectance spectra (UV-Vis DRS). The photocatalytic activity of N–NaTaO₃ was evaluated by decomposing Rhodamine B (RhB) under UV-light irradiation. The results revealed that the as-treated NaTaO₃ possessed monoclinic lattice when the annealing temperature was below 650 °C, while the higher temperature distorted lattice structure resulting in the formation of Ta₃N₅ and poor photocatalytic performance. The photocatalytic activity of the N–NaTaO₃ confirmed that a proper N content was crucial to expand the adsorption region of light, as well as to enhance photocatalytic efficiency. Moreover, the N–NaTaO₃ products with doped-N/Ta ratio of about 0.06 exhibited the highest photocatalytic activity, having 10 times higher degradation rate constant than those of the as-prepared NaTaO₃, and possessed outstanding cycle stability.