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Environmentally benign zinc sulfide (ZnS), consisting entirely of “active” sites, has shown promising efficiency for capturing mercury from flue gas in recent experimental studies. In this work, the binding mechanism of Hg⁰ on the ZnS(110) surface was investigated by the density functional theory (DFT) method. Meanwhile, the binding of two additional mercury forms, HgCl and HgCl₂, and three essential flue gas components, H₂O, SO₂, and HCl, and their further effects on the strength of Hg⁰ binding on the ZnS(110) surface were also evaluated. The results showed that, consistent with experimental observations, Hg⁰ can be chemisorbed on the ZnS(110) surface with binding energies (BEs) as high as −87.80 kJ/mol. The enhanced electrostatic characteristics on the activated surface, especially the Zn sites, are beneficial to exciting the outer-shell electrons of Hg⁰ and thereby enhancing the binding strength of the …