Rational design bionic flower-like BiOBr0.5I0.5/WS2 Z-scheme heterojunction for efficient oxidation of Hg0: Synergistic effect of facets exposed and intrinsic defects

Gaseous zero-valent mercury (Hg0) emitted from coal-fired power plants results in serious environmental problems, therefore, it is important to remove Hg0 emitted from the power plants. Herein, a novel material with a flower-shaped spherical appearance was used for the removal of Hg0. A BiOBr0.5I0.5/WS2 solid solution with {1 1 0} exposed facets of BiOBr0.5I0.5 and {1 0 4} exposed WS2 facets was synthesised through a simple self-assembly method. BiOBr0.5I0.5/WS2 exhibited excellent photoactivity under visible light, which is attributed to the synergetic effects of the exposed low facets, high surface area, and optimized band structure. Particularly, a 40- wt%-WS2-coated BiOBr0.5I0.5 photocatalyst exhibited the highest Hg0 removal of 87.52% via photocatalytic oxidation. These Z-scheme heterojunction with facets exposed can efficient separate electron-hole pairs and improve the visible light absorption performance. Further analysis indicate that BiOBr0.5I0.5/WS2 is an effective photocatalyst for solar energy utilization and environmental remediation.