Synthesis of three-dimensional (3D) hierarchical hollow spheres with exposed {0 0 1} active facets are of huge significance in the field of semiconductor photocatalysis. Herein, we demonstrate a facile ionic liquid-in-water (IL/W) microemulsion approach for the fabrication of Bi-rich Bi3O4Br hierarchical hollow spheres assembled with {0 0 1}-facets exposed nanosheets. The size and {0 0 1}-facets exposure ratio of Bi3O4Br hierarchical hollow spheres can be fine-tuned by adjusting the concentration of surfactant TX-100. A possible formation mechanism of Bi3O4Br hierarchical hollow spheres assembled with {0 0 1}-facets exposed nanosheets by microemulsion template and dissolution-recrystallization was proposed based on SEM and XRD results. The actual photocatalytic activity was extensively investigated by degrading multiform phenol derivatives with different substituents and substitution positions, including acetaminophen (APAP), 4-tert-butylphenol (PTBP), o-nitrophenol (ONP), methylparaben (MPB). The Bi3O4Br hierarchical hollow spheres assembled with {0 0 1}-facets exposed nanosheets not only exhibit significantly promoted visible-light photocatalytic activity, but also have robust and nonselective photooxidation ability. The photocurrent and impedance results indicated that significantly strengthened charge separation and transfer efficiency that derived from the advantages of Bi3O4Br {0 0 1} active facets and hollow structures were responsible for the high photo-activity. The study may provide some new hints on designing and developing novel 3D hierarchical hollow structures with exposing {0 0 1} active facets for heterogeneous photocatalysis. (C) 2018 Published by Elsevier Inc.