Ta3N5 nanoparticles with enhanced photocatalytic efficiency under visible light irradiation.

Nanocrystalline Ta(3)N(5) particles with a surface area of more than 33 m(2)/g were synthesized by nitridation of nanosized Ta(2)O(5) particles using NH(3) as the reactant gas. It was found that nanocrystalline Ta(2)O(5) was converted into Ta(3)N(5) completely (by X-ray diffraction, XRD) at 700 degrees C within 5.0 h, which was much lower than the temperature 900 degrees C for the complete nitridation of micrometer-sized Ta(2)O(5) powder. The oxide precursor and the resulting nitride were characterized by XRD analysis, transmission electron microscopy, UV-vis diffuse reflectance spectra, and BET surface area techniques. The nitrogen contents in the prepared Ta(3)N(5) powders were quantitatively determined with a CHN elemental analyzer. Nanocrystalline Ta(3)N(5) showed an absorption edge of around 600 nm, and Ta(3)N(5) in the size of about 26 nm exhibited a blue shift of 15 nm in the adsorption edge. The photocatalytic activity of the prepared Ta(3)N(5) under UV-vis and visible light irradiation was compared to that of nanocrystalline TiO(2-x)N(x) using the photocatalytic degradation of methylene blue (MB) as a model reaction. The Ta(3)N(5) nanoparticles showed the significantly enhanced photocatalytic activity for the degradation of MB in comparison with the larger-sized Ta(3)N(5). Moreover, the nanocrystalline Ta(3)N(5) showed much higher photocatalytic activity under visible light irradiation compared with TiO(2-x)N(x) in the same size.