Unlocking the Potential of Metal Sulfides and Edge Plane Engineering for High-Capacity Thallium Adsorption from Non-ferrous Smelting Gas

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 S22– 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.