Ta3N5 nanoparticles with enhanced photocatalytic efficiency under visible light irradiation

Nanocrystalline Ta3N5 particles with a surface area of more than 33 m(2)/g were synthesized by nitridation of nanosized Ta2O5 particles using NH3 as the reactant gas. It was found that nanocrystalline Ta2O5 was converted into Ta3N5 completely (by X-ray diffraction, XRD) at 700 degreesC within 5.0 h, which was much lower than the temperature 900 degreesC for the complete nitridation of micrometer-sized Ta2O5 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 Ta3N5 powders were quantitatively determined with a CHN elemental analyzer. Nanocrystalline Ta3N5 showed an absorption edge of around 600 nm, and Ta3N5 in the size of about 26 nm exhibited a blue shift of 15 nm in the adsorption edge. The photocatalytic activity of the prepared Ta3N5 under UV-vis and visible light irradiation was compared to that of nanocrystalline TiO2-xNx using the photocatalytic degradation of methylene blue (MB) as a model reaction. The Ta3N5 nanoparticles showed the significantly enhanced photocatalytic activity for the degradation of MB in comparison with the larger-sized Ta3N5. Moreover, the nanocrystalline Ta3N5 showed much higher photocatalytic activity under visible light irradiation compared with TiO2-xNx in the same size.