A Lacunary Polyoxometalate Anion Tightly Sealed in a ZIF‐8 Polyhedron with Ultrafast Cationic Dye Adsorption

Abstract Finding efficient materials for treatment of dye wastewater is a hot research topic in the field of environmental science. In this paper, the mono‐lacunary polyoxometalate anion (SiW 11 ) is completely sealed in a zeolitic imidazolate (ZIF‐8) polyhedron, forming a new polyhedral absorbent, SiW 11 @ZIF‐8, with an intact surface and a negative charge center. Unlike saturated Keggin type polyoxoanions, SiW 11 is only stable under neutral conditions and does not release any protons in solutions. Therefore, SiW 11 @ZIF‐8 does not display the usually observed acid‐induced etching and shows effective and ultrafast adsorption for the cationic dye methylene blue. This work not only indicates that the neutral polyoxoanion is a more suitable candidate to be sealed in ZIF‐8 to form a stable unpunched composite, but also provides a new concept for the design of stable polyoxometalate@ZIF adsorbents to be potentially used in the treatment of cationic dyes in wastewater.