Fe3 + Activation of Metal Sulfides for High-Performance Mercury Removal from Nonferrous Smelting Gas: A Dual Mercury Adsorption Mechanism

Abstract Atmospheric elemental mercury (Hg0) emitted from the nonferrous metallurgy industry poses severe risks to ecosystems. Although metal sulfides are promising in Hg0 adsorption under high-concentration SO2 conditions, they typically suffer from poor performance at elevated temperatures due to weak binding affinity. Herein, a trivalent iron (Fe3+) activation strategy to boost Hg0 adsorption activity of metal sulfides was developed for the first time, which leverages electron-deficient Fe3+ to induce electronic reconstruction. This Fe3+ activation strategy is applicable to various metal sulfides, generating Fe sites with high activity and stability. Among the various candidates, the Fe3+-activated MoS2 delivers a record-theoretical saturated Hg0 adsorption capacity of 69.56 mg·g–1 at 150 °C, which is 4.35 times higher than that of pristine MoS2. The sulfur vacancies on MoS2 serve as the key anchoring sites for Fe3+, generating stable single-atom, dimer, and trimer Fe configurations. These new Fe centers, benefiting from charge modulation, can simultaneously adsorb two Hg atoms via charge transfer and orbital hybridization. The Fe3+-activated MoS2 exhibits strong resistance to SO2 and H2O, maintaining high Hg0 removal efficiency under a smelting gas atmosphere. This work reveals new configurations of Hg adsorption and provides a convenient route to design high-performance sorbents for heavy metal purification.