Ta_3N_5 Nanoparticles with Enhanced Photocatalytic Efficiency under Visible Light Irradiation

摘要

Nanocrystalline Ta_3N_5 particles with a surface area of more than 33 m~2/g were synthesized by nitridation of nanosized Ta_2O_5 particles using NH_3 as the reactant gas.It was found that nanocrystalline Ta_2O_5 was converted into Ta_3N_5 completely(by X-ray diffraction,XRD)at 700 deg C within 5.0 h,which was much lower than the temperature 900 deg C for the complete nitridation of micrometer-sized Ta_2O_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_3N_5 powders were quantitatively determined with a CHN elemental analyzer.Nanocrystalline Ta_3N_5 showed an absorption edge of around 600 nm,and Ta_3N_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_3N_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_3N_5 nanoparticles showed the significantly enhanced photocatalytic activity for the degradation of MB in comparison with the larger-sized Ta_3N_5.Moreover,the nanocrystalline Ta_3N_5 showed much higher photocatalytic activity under visible light irradiation compared with TiO_(2-x)N_x in the same size.