The MOF+ Technique: A Significant Synergic Effect Enables High Performance Chromate Removal

A significant synergic effect between a metal–organic framework (MOF) and Fe₂SO₄, the so‐called MOF⁺ technique, is exploited for the first time to remove toxic chromate from aqueous solutions. The results show that relative to the pristine MOF samples (no detectable chromate removal), the MOF⁺ method enables super performance, giving a 796 Cr mg g⁻¹ adsorption capacity. The value is almost eight‐fold higher than the best value of established MOF adsorbents, and the highest value of all reported porous adsorbents for such use. The adsorption mechanism, unlike the anion‐exchange process that dominates chromate removal in all other MOF adsorbents, as unveiled by X‐ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and transmission electron microscopy (TEM), is due to the surface formation of Fe_0.75Cr_0.25(OH)₃ nanospheres on the MOF samples.