Unlocking the Potential of Metal Sulfides and Edge Plane Engineering for High-Capacity Thallium Adsorption from...

As a highly toxic heavy metal, the atmospheric thallium (Tl) emission from non-ferrous smelting has gained increasing attention, yet it still lacks a sufficient understanding of gaseous thallium purification through adsorption. Herein, we demonstrate for the first time that metal sulfides, including MoS₂, CuS, and ZnS, are active in TlCl adsorption, wherein MoS₂ exhibits the best activity. A crystal plane engineering strategy was proposed to fabricate the edge plane of MoS₂, uncovering a critical law that the TlCl adsorption ability of MoS₂ highly depends on the formation of edge sites. Edge-enriched MoS₂ realizes a record TlCl adsorption capacity of 159.3 mg g^-1 at 250 °C under a pure N₂ atmosphere, which is two times higher than the current sorbents. Both Mo⁶⁺ and S₂^2- are active centers for getting electrons from Tl⁺ and achieving the chemisorption of TlCl. Electron density difference analyses verify the stronger activity of edge Mo sites in withdrawing electrons from Tl⁺ than the basal S sites. MoS₂ displays strong resistance to SO₂ and H₂O and can utilize O₂ to generate Mo⁶⁺ species, which ensures its stability for TlCl adsorption under smelting gas. This work establishes metal sulfides as promising sorbents for gaseous Tl removal and introduces new insights into the design of high-performance sorbents for heavy metal control.