Disordered MoS2 Nanosheets with Widened Interlayer Spacing for Elemental Mercury Adsorption from Nonferrous Smelting Flue Gas

The development of a sorbent with a large elemental mercury (Hg-0) adsorption capacity under a high SO2 concentration atmosphere is the key point for mercury emission control from nonferrous smelting (NFS) flue gas. By controlling the degree of crystallization, oxygen incorporation and disorder engineering were simultaneously realized to improve the Hg-0 adsorption capacity of MoS2 nanosheets for the first time. The interlayer spacing of oxygen-incorporated MoS2 nanosheets reaches up to 9.4 A from 6.4 A of normal MoS2 nanosheets, which enhances the exposure of the active sites. Oxygen-incorporated MoS2 nanosheets display a disordered structure, indicating the declined crystallinity and increased active sites. Benefiting from the above synergistic advantages, oxygen incorporation and structure disorder increases significantly the equilibrium Hg-0 adsorption capacity of MoS2 nanosheets to 16.26 mg.g(-1) under 6% SO2 atmosphere, which is about 2.5 times larger than that of normal MoS2 nanosheets. Both external mass transfer and chemisorption control He adsorption on MoS2. Surface Mo5+ and S-2(2-) act as the main active sites generated by disorder engineering for capturing Hg-0, and HgS is the final product of Hg-0 adsorption. The simultaneous optimization of structural and chemical properties in this work provides an effective and convenient strategy to improve the He adsorption capacity of MoS2 nanosheets.