As a highly toxic pollutant, mercury poses a serious threat to humans worldwide. Among the many forms of mercury, elemental mercury (Hg⁰) is an important product in the metallurgy and recycling industries. Therefore, it is urgent to adopt low-cost prevention measures to control Hg⁰ pollution and store mercury resources. In this work, a series of carbon-based materials with different coordination environments and atomic dispersion of single-site manganese were prepared, and their elemental mercury removal performance was systematically investigated. It was demonstrated that the coordination environment around manganese determines its electronic structure and size, thus affecting its affinity with mercury. The obtained best adsorbents atomically dispersed Mn with atom size near 0.2 nm, achieves high Hg⁰ removal efficiency and over 13 mg/g Hg⁰ adsorption capacity at 200°C. And the SO₂ resistance performance of single atoms (∼0.2 nm) is much better than clusters (∼1−2 nm) because of its high selectivity, that the effect of SO₂ is only 3%. Density functional theory (DFT) reveals that Mn with four-nitrogen atoms (Mn−N₄-C-O) is more active than other number nitrogen coordination materials. Moreover, the presence of carboxyl groups around manganese also promotes affinity for Hg⁰. This work might shed new light on the enhancement of Hg⁰ affinity in carbon-based materials and the rational design of the coordination structure of the tunable Hg⁰ activities.

Jiaxing Li

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