Hierarchical magnetic BiFeO3 microcages: Controlling synthesis and visible-light photocatalytic activity

Abstract Hierarchical BiFeO3 microcages were prepared from a Bi3+-modified Fe-MOF using a feasible and controllable strategy, which involved the doping of Bi3+ into Fe-MOF and subsequent annealing of the precursors. The as-formed BiFeO3 microcages calcined at 600 °C were hierarchically composed of numerous aggregated nanoflakes. The characteristics of the ordered stacked structure and high purity of the BiFeO3 architecture are attributable to the slow self-sacrificing template effect. The obtained BiFeO3 microcages exhibited remarkable visible-light-driven photocatalytic activity for the use in decomposing methylene blue (MB) dye molecules as well as excellent reusability due to their superior magnetic separability. Photocatalytic mechanism studies demonstrated the dominant roles of O2•- and •OH intermediate species involved in MB degradation. The presented surface modification and self-sacrifice templating strategy provide possibilities for precise design and control of other novel semiconductors with intriguing morphologies, compositions, and tunable functions.