Enhanced photocatalytic performance of Bi4O5Br2 with three-dimensionally ordered macroporous structure for phenol removal

Herein, a series of three-dimensionally ordered macroporous (3DOM) Bi4O5Br2 photocatalysts with different macropore sizes were successfully fabricated via a polymethyl methacrylate (PMMA) template method. The photocatalytic activity for phenol degradation over 3DOM Bi4O5Br2 first increased and then decreased with the rise in macropore size. Specifically, 3DOM Bi4O5Br2-255 (macropore diameter ca. 170 nm) exhibits the best photocatalytic activity in the static system, which is about 4.5, 7.3, and 11.9 times higher than those of bulk Bi4O5Br2, Bi2WO6, and g-C3N4, respectively. Meanwhile, high phenol conversion (75%) is also obtained over 3DOM Bi4O5Br2-255 in the flow system under full spectrum irradiation. Furthermore, 3DOM Bi4O5Br2-255 also shows strong mineralization capacity owing to the downward shift of valance band position (0.15 V) as compared with Bi4O5Br2. Total organic carbon (TOC) removal rate over 3DOM Bi4O5Br2-255 (62%) is much higher than that of Bi4O5Br2 (17%). The enhancement in photocatalytic performance of 3DOM Bi4O5Br2-255 is attributable to its better phenol adsorption, O2 activation, and charge separation and transfer abilities. This work combines the advantages of 3D structure and surface dangling bonds, providing new possibilities for designing highly efficient photocatalysts for pollutants removal.