Released Defective Nb2O5 with Optimized Solar Photocatalytic Activity

Released niobium pentoxide (Nb2O5) nanostructured powders were firstly prepared by a continuous electrochemical anodization under mild reaction conditions. The powders show mainly tube morphology, with the crystalline phase (amorphous, hexagonal, or orthorhombic), crystallinity, surface area (42.3-132.9 m(2) g(-1)), and bandgap (3.1-3.7 eV) strongly dependent on the crystallization condition. The photocatalytic (PC) activity of the powder photocatalyst was investigated by photodegradation of methylene blue under UV light and full-spectrum solar light illuminations. The powder annealed at a low temperature of 350 degrees C shows visible-lightresponse photoactivity and also the highest PC efficiencies. The kinetic rate constant under solar light illumination is 0.135 min(-1) for the 350 degrees C annealed powder, which is nearly 2.4, 5.9, 15, and 45 times of the 550 degrees C-annealed, as-formed, 750 degrees C-annealed, and commercial ones, respectively. The excellent PC performance is mainly attributed to the high surface area and enhanced surface oxygen vacancies that allow a high and broad light absorption in the visible region. The synthesis method provides low-cost, efficient, continuous, and mass production of nanoporous Nb2O5 for broad applications. (c) 2017 The Electrochemical Society. All rights reserved.