A Layered Cationic Aluminum Oxyhydroxide as a Highly Efficient and Selective Trap for Heavy Metal Oxyanions

Cationic framework materials, especially pure inorganic cationic frameworks that can efficiently and selectively capture harmful heavy metal oxyanions from aqueous solution are highly desired yet scarcely reported. Herein, we report the discovery of a 2D cationic aluminum oxyhydroxide, JU‐111, which sets a new benchmark for heavy metal oxyanion sorbents, especially for CrVI. Its structure was solved based on 3D electron diffraction tomography data. JU‐111 shows fast sorption kinetics (ca. 20 min), high capture capacity (105.4 mg g−1), and broad working pH range (3–10) toward CrVI oxyanions. Unlike layered double hydroxides (LDHs), which are poorly selective in the presence of CO32−, JU‐111 retains excellent selectivity for CrVI even under a large excess of CO32−. These superior features coupled with the ultra‐low cost and environmentally benign nature make JU‐111 a promising candidate for toxic metal oxyanion remediation as well as other potential applications.