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. Experimental results show that the reductive pre-annealing yielded more surface-chemisorbed oxygen by introducing lower valance Fe₂₊ and Ti₃₊ ions. The specific surface area, methylene blue adsorption and photoabsorption threshold of the nanotubes were greatly enhanced by the reductive annealing when comparing with annealing in air. 1 mol% Fe doping and the reductive annealing yielded the highest adsorption, photocatalytic efficiency and durability for degradation of MB solution; extreme Fe doping decreased the photocatalytic efficiency. The Fe content of the nanotubes was 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.