Controlled Synthesis of Hollow α-Fe2O3 Microspheres Assembled With Ionic Liquid for Enhanced Visible-Light Photocatalytic Activity

Abstract

Porous self-assembled α-Fe₂O₃ 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 [C₄Mim]BF₄) was found to play a crucial role in the control of these α-Fe₂O₃ hollow structures. Trace amounts ionic liquid was used as the soft template to synthesize α-Fe₂O₃ hollow spheres with a large specific surface (up to 220 m²/g). Based on time-dependent experiments, the proposed formation mechanisms were presented. Under UV light irradiation, the as-synthesized α-Fe₂O₃ hollow spheres exhibited excellent photocatalysis in Rhodamine B (RhB) photodegradation and the rate constant was 2-3 times higher than α-Fe₂O₃ particles. The magnetic properties of α-Fe₂O₃ hollow structures were found to be closely associated with the shape anisotropy.