Core-shell structured alpha-Fe2O3@TiO2 nanocomposites with improved photocatalytic activity in the visible light region

The core-shell structured Fe2O3@TiO2 nanocomposites prepared via a heteroepitaxial growth route using the Fe2O3 spindle as a hard template display improved photocatalytic degradation activity for Rhodamine B dye under visible light irradiation. The ratio of alpha-Fe2O3:TiO2 in the alpha-Fe2O3@TiO2 core-shell nanocomposites can be tuned by etching the alpha-Fe2O3 core via controlling the concentration of HCl and etching time. An appropriate concentration of the Fe2O3 core could effectively induce a transition of the optical response from the UV to the visible region and decrease the recombination rate of photogenerated electrons and the holes of the core-shell structured catalyst, greatly contributing to the enhancement of visible light response and visible light photocatalytic activity of the Fe2O3@TiO2 catalysts. It is revealed that the optical response and photocatalytic performance of the core-shell alpha-Fe2O3@TiO2 nanocomposites can be tuned by adjusting the molar ratio of Fe2O3:TiO2 of the alpha-Fe2O3@TiO2 nanocomposites. The alpha-Fe2O3@ TiO2 core-shell nanocomposite with an optimal molar ratio of 7% for Fe2O3:TiO2 exhibits the best photocatalytic performance under visible light irradiation. It is shown that the Fe2O3/TiO2 heterojunction structure is responsible for the efficient visible-light photocatalytic activity. As the concentration of Fe2O3 is high, Fe3+ ions will act as recombination centres of the photogenerated electrons and holes. The present core-shell Fe2O3@TiO2 nanoparticles displaying enhanced photodegradation activity could find potential applications as photocatalysts for the abatement of various organic pollutants.