Photocatalytic degradation of an azo dye using N-doped NaTaO3 synthesized by one-step hydrothermal process.

N-doped NaTaO(3) compounds (NaTaO(3-)(x)N(x)) with nano-cubic morphology were successfully synthesized by one-step hydrothermal method and Methyl Orange (MO) was used as a model dye to evaluate their photocatalytic efficiency under visible-light irradiation. The as-prepared NaTaO(3-)(x)N(x) samples were characterized by various techniques, such as X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and UV-vis diffuse reflectance spectra and GC-MS. The results indicate that NaTaO(3-)(x)N(x) displays a pure perovskite structure when the synthesis temperature is higher than 180°C. Moreover, as observed by SEM images, the particles of resultant NaTaO(3-)(x)N(x) show cubic morphology with the edge length of 200-500nm, which can be easily removed by filtration after photocatalytic reaction. Doping of N increases the photocatalytic activity of NaTaO(3), and NaTaO(2.953)N(0.047) shows the highest visible-light photocatalytic activity for the degradation of MO. Based on the experiment results, a possible mechanism of the photocatalysis over NaTaO(3-)(x)N(x) and the photodegradation pathway of MO were proposed.

Synthesis and photocatalytic activity of N-doped NaTaO3 compounds calcined at low temperature.

N-doped NaTaO(3) compounds (NaTaO(3-x)N(x)) were successfully synthesized using NaTaO(3) prepared at low calcination temperature as starting material and melamine (C(3)H(6)N(6)) as nitrogen source. The as-prepared NaTaO(3-x)N(x) samples were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and UV-vis diffuse reflectance spectra. The XRD results indicate that the crystallization temperature of NaTaO(3) is up to 700 degrees C and the doping of N does not lead to significant structural changes. Moreover, as observed by SEM images, the particle sizes of resultant NaTaO(3-x)N(x) are in the range of 100-150 nm, which are much smaller than NaTaO(3) particles synthesized by traditional solid state reaction method. The photocatalytic activities of NaTaO(3-x)N(x) were examined by methylene blue (MB) aqueous solution under UV light. It is found that the photocatalytic activity of NaTaO(3-x)N(x) depend strongly on the doping content of N, and sample NaTaO(2.961)N(0.039) shows the highest photocatalytic activity for the degradation of MB. Furthermore, it is also found that NaTaO(3-x)N(x) catalysts display super structural stabilities during photocatalytic degradation, and could recover their photocatalytic activity after calcination at 500 degrees C, suggesting a promising utilization of such photocatalyst.