Strengthen the Affinity of Element Mercury on the Carbon-Based Material by Adjusting the Coordination Environment of Single-Site Manganese

Mercury, as a highly poisonous pollutant, poses a severe threat to the global population. However, the removal of Hg-0 can only be carried out at below 100 degrees C due to the weak binding of the adsorbent. Herein, 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 Hg-0 removal efficiency and over 13 mg/g Hg-0 adsorption capacity at 200 degrees C. And the SO2 resistance performance of single atoms (similar to 0.2 nm) is much better than clusters (similar to 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-N-4-C = O) is more active than other number nitrogen coordination materials. Moreover, the presence of carboxyl groups around manganese also promotes affinity for Hg-0. This work might shed new light on the enhancement of Hg-0 affinity in carbon-based materials and the rational design of the coordination structure of the tunable Hg-0 activities.

Automated summary

This study systematically investigated the elemental mercury removal performance of carbon-based materials with different coordination environments and single-site manganese dispersion. The research found that the coordination environment around manganese can affect its affinity with mercury, thus influencing the adsorption capacity. It was demonstrated that single-site manganese with an atom size near 0.2 nm achieves high Hg-0 removal efficiency at 200 degrees C.