Efficient mercury chloride capture by ultrathin 2D metal-organic framework nanosheets

Abstract The retrieval of toxic heavy metals ions from aqueous resources effectively and facilely, by using low-cost, robust, and efficient technologies, is imperative and of significant environmental and societal importance. Adding on, the comprehensive utilization of the captured heavy metals remains a huge challenge. Herein, we demonstrate that the single-layered sulfur-rich two-dimensional (2D) metal-organic frameworks (MOFs) nanosheets 2D-NCS ({[Co(NCS)2(pyz)2]}n) (pyz = pyrazine), which featured with the merits of ultrahigh sulfur content (19.1%), tremendous affinity of thiocyanate group, and fully accessible chelating sites arrayed on the double surfaces of the nanosheets, serving as an ideal adsorbent materials for mercury chloride capture from aqueous solution, with considerable capacity, efficiency, effectivity and recycling ability. The maximum uptake capacity is found to be 1698 mg g−1, accompanied by high affinity (Kd value of 2.26 × 106 mL g−1) and extremely fast kinetics (reduce the mercury concentration from 10 ppm to 1 ppb within 15 min). More importantly, 2D-NCS can act as versatile building blocks for the construction of solid three-dimensional porous architecture 2D-NCS@Hg, achieving the challenging goal of “turning waste into treasure”. These results have demonstrated the enormous potential of ultrathin 2D MOFs nanosheets for high-performance environmental remediation.