Fabrication of a Z-Scheme Heterojunction Polyhedral-Shaped BiOIO3/MIL-53(Fe) Photocatalyst for Enhancing Gaseous Hg0 Removal

A Z-scheme heterojunction polyhedral-shaped BiOIO3/MIL-53(Fe) photocatalyst is prepared by a solvothermal method. The samples are characterized by XRD, XPS, SEM, TEM, FT-IR, UV–vis, PL, and other material characterization analysis methods. The photocatalytic performance of photocatalysts is studied for removal of vapor-phase mercury (Hg0) under visible-light irradiation. The results suggest that the Hg0 removal efficiency of the BiOIO3/MIL-53(Fe) composite is significantly improved compared with that of MIL-53(Fe). When the molar ratio of BiOIO3 and MIL-53(Fe) is 2:1, the BiOIO3/MIL-53(Fe) composite photocatalyst exhibits the best Hg0 removal efficiency, reaching 74.19%. BiOIO3 and MIL-53(Fe) form a Z-scheme heterojunction with a suitable energy band structure, which results in the effective separation of photoinduced electron–hole pairs and delays their recombination. Finally, the photocatalytic oxidation mechanism of Hg0 by the BiOIO3/MIL-53(Fe) composite is proposed, which paves the way for the study of the built-in electric field and electron transport channels between binary photocatalyst materials.