Interface modulation of Mn-N4-C with optimized oxygen-containing functional groups for highly efficient mercury adsorption

To achieve enhanced capture performance of industrial gaseous mercury pollution in heterogeneous reactions, the directed construction of an active reaction interface is particularly critical. Here, we developed atomically dispersed manganese confined within a carbon framework doped with heteroatoms (Mn-N4-C) for strengthening the adsorption of elemental mercury at the interface. The results demonstrate that the adsorption performance of Mn-N4-C is primarily determined by the surrounding coordination environment of individual metal sites. Due to the unique axial-coordination microenvironment, Mn-N4-C with abundant oxygen-containing functional groups (Mn-N4-C(EDA)) exhibits excellent affinity towards elemental mercury, with an adsorption capacity of up to 29.5 mg/g surpassing the most carbon-based materials. Furthermore, it also exhibits excellent tolerance towards various industrial flue gas conditions, performing an adsorption capacity of 16.4 +/- 0.2 mg/g within the wide temperature range of 20-200 degrees C and being promoted by the NO, HCl and H2O, which facilitates practical industrial applications. Theoretical simulations further indicate that the bonding between individual Mn and oxygen sites significantly enhances the mercury adsorption capability of Mn-O-N4 sites, benefiting from the optimization of manganese's electronic structure by oxygen-containing species. Therefore, this study presents a multitude of opportunities for enhancing the adsorption of elemental mercury at interfaces through the directed modulation of metal-oxygen bonds(M-O).

Automated summary

This study developed atomically dispersed manganese confined within a carbon framework doped with heteroatoms (Mn-N4-C) to enhance the adsorption of elemental mercury at interfaces. The surrounding coordination environment of individual metal sites primarily determined the adsorption performance of Mn-N4-C. Mn-N4-C with abundant oxygen-containing functional groups (Mn-N4-C(EDA)) exhibited excellent affinity towards elemental mercury, surpassing most carbon-based materials. It also showed tolerance towards various industrial flue gas conditions and was promoted by NO, HCl, and H2O, making it suitable for practical industrial applications.