One-step solvothermal preparation of visible light-driven N-modified Nb2O5 photocatalyst using nitric acid as the nitrogen source

This letter reports the preparation of visible light-driven N-modified Nb2O5 photocatalyst by an alternative one-step solvothermal route, which employs nitric acid as the nitrogen source. N-modified Nb2O5 nanoparticles (which were abbreviated as Nb2O5-HNO3) were prepared directly through the solvothermal reactions of NbCI5, nitric acid (14.36-15.16 mol/L) and absolute ethanol at 200 degrees C for 15 h. The composition, structure and photoabsorption feature of Nb2O5-HNO3 were characterized by X-ray photoelectron spectroscopy, transmission electron microscopy, N-2 adsorption/desorption isotherms and UV-vis diffuse reflectance spectroscopy. The photocatalytic activity of Nb2O5-HNO3 was examined in the reduction of aqueous Cr(VI) under visible light (lambda >420 nm) irradiation, and compared with that of Nb2O5-NH3 (which denoted the sample prepared when 13.32-14.44 mol/L ammonia water replaced nitric acid). It was observed that Nb2O5-HNO3 displayed distinct absorption of visible light and high photocatalytic activity in the reduction of aqueous Cr(VI) under visible light (lambda >420 nm) irradiation, whereas Nb2O5-NH3 exhibited no visible light-absorbing ability and no visible light-driven photocatalytic activity. This work suggests that nitric acid is an alternative nitrogen source for one-step solvothermal preparation of visible light-driven N-modified Nb2O5 photocatalyst. (C) 2015 Elsevier B.V. All rights reserved.