Hematite with the Urchinlike Structure: Its Shape-Selective Synthesis, Magnetism, and Enhanced Photocatalytic Performance after TiO2 Encapsulation

In this work, a facile route using simple a hydrothermal reaction and sequential calcinations for the selective synthesis of 3D alpha-Fe2O3 Urchinlike nanostructures without employing templates or matrixes is presented. By hydrolyzing FeCl3 in the solution containing different anions (SO42-, Cl-, NO3-, ClO3-, ClO4-, C2O4-, Br-), product with certain morphology can be selectively synthesized. The effect of inorganic anions on the morphologies and sizes of the products was systematically investigated. A probable formation mechanism for the urchinlike nanostructure was proposed. Magnetic hysteresis measurements of the as-obtained products reveal that magnetic properties of products were shape-dependent. The as-obtained alpha-Fe2O3 nanostructures show photocatalytic activity on the decomposition of RhB upon irradiation by the UV light. The photocatalytic performance can be further enhanced by TiO2 coating,