Effects of Pre-annealing Atmosphere on Microstructure and Photocatalytic Activities of Fe-doped Titania Nanotubes

Abstract

The nanotubes with an anatase structure were hydrothermally synthesized using the Fe-doped anatase nanopowder precursors that were annealed in air and reductive atmospheres. The microstructure and physicochemical properties of the nanotubes were comparably investigated. Results show that the reductive pre-annealing yields more surface-chemisorbed oxygen by introducing lower valance Fe 2+ and Ti 3+ ions. The specific surface area, methylene blue adsorption and photoabsorption threshold of the nanotubes are greatly enhanced by the reductive annealing when comparing with annealing in air. 1 mol% Fe doping and reductive annealing yield the highest adsorption, photocatalytic efficiency and durability for degradation of MB solution; extreme Fe doping decreases the photocatalytic efficiency. The Fe content of the nanotubes is decreased by the hydrothermal synthesis, especially in the case of annealing in air. Moreover, the action mechanism of the Fe doping and reductive annealing was discussed.