Engineering unsaturated sulfur site in three-dimension MoS2@rGO nanohybrids with expanded interlayer spacing and disordered structure for gaseous elemental mercury trap

• A strategy of expanding interlayer spacing of MoS 2 was proposed. • The graphene oxide carrier facilitates the formation of unsaturated sulfur site. • The as-prepared W-D-MoS 2 @rGO exhibits an excellent Hg 0 capture performance. • Abundant and thermostable unsaturated sulfurs is vital for Hg 0 adsorption. • Edge sulfur vacancy site has the lowest adsorption energy for Hg 0 capture. Rapid and effective capture of gaseous elemental mercury (Hg 0 ) over a wide operating temperature range is significant for the green and sustainable development of nonferrous smelting industry. High mercury affinity and strong sulfur resistance of two-dimensional layered MoS 2 render it an outstanding adsorbent for Hg 0 trap. However, the relative lack of serviceable active sites greatly suppresses its extensive application. Herein, a feasible strategy to expand interlayer spacing, build disordered structure and engineer unsaturated sulfur adsorption sites was provided through the construction of three-dimension MoS 2 @rGO nanohybrids. As expected, compared with bulk and ordered MoS 2 , the prepared MoS 2 @rGO hybrid exhibits a remarkable performance improvement for Hg 0 adsorption. The average Hg 0 adsorption rate of MoS 2 @rGO is 2.28 μg/g/min and its saturated adsorption capacity reaches 20.91 mg/g. The typical components in nonferrous flue gas have almost no effect on Hg 0 adsorption performance. X-ray photoelectron spectroscopy confirms that the formation of abundant unsaturated coordination sulfurs sites with high thermostability is critical for Hg 0 adsorption performance improvement. Moreover, the density functional theory calculation results further demonstrate the high adsorption activity of unsaturated coordination sulfur sites for Hg 0 capture. Among these sulfur sites, edge sulfur vacancy site plays a dominant role for Hg 0 adsorption because of the lowest Hg 0 adsorption energy. The final adsorption production is HgS which has negligible environmental toxicity due to its extreme stability. This work not only provides a promising adsorbent for Hg 0 removal in industrial application, but also opens up an avenue to engineer unsaturated sulfur for other layered transition metal dichalcogenides.