Controlled Synthesis of Hollow α-Fe(2)O(3) Microspheres Assembled With Ionic Liquid for Enhanced Visible-Light Photocatalytic Activity

Porous self-assembled α-Fe(2)O(3) hollow microspheres were fabricated via an ionic liquid-assisted solvothermal reaction and sequential calcinations. The concentration of the ionic liquid (1-butyl-3-methylimidazolium tetrafluoroborate [C(4)Mim]BF(4)) was found to play a crucial role in the control of these α-Fe(2)O(3) hollow structures. Trace amounts ionic liquid was used as the soft template to synthesize α-Fe(2)O(3) hollow spheres with a large specific surface (up to 220 m(2)/g). Based on time-dependent experiments, the proposed formation mechanisms were presented. Under UV light irradiation, the as-synthesized α-Fe(2)O(3) hollow spheres exhibited excellent photocatalysis in Rhodamine B (RhB) photodegradation and the rate constant was 2–3 times higher than α-Fe(2)O(3) particles. The magnetic properties of α-Fe(2)O(3) hollow structures were found to be closely associated with the shape anisotropy.