Metallic 1T/1T' phase TMD nanosheets with enhanced chemisorption sites for ultrahigh-efficiency lead removal.

Two-dimensional (2D) materials, as adsorbents, have garnered great attention in removing heavy metal ions (HMIs) from drinking water due to their extensive exposed adsorption sites. Nevertheless, there remains a paucity of experimental research to remarkably unlock their adsorption capabilities and fully elucidate their adsorption mechanisms. In this work, exceptional lead ion (Pb) (a common HMI) removal capacity (up to 758 mg g) is achieved using our synthesized metallic 1T/1T' phase 2D transition metal dichalcogenide (TMD, including MoS, WS, TaS, and TiS) nanosheets, which hold tremendous activated S chemisorption sites. The residual Pb concentration can be reduced from 2 mg L to 2 μg L within 0.5 min, meeting the drinking water standards following World Health Organization guideline (Pb concentrations <10 μg L). Atomic-scale characterizations and calculations based on density functional theory unveil that Pb bond to the top positions of transition metal atoms in a single-atom form through the formation of S-Pb bonds. Point-of-use (POU) devices fabricated by our reported metallic phase MoS nanosheets exhibit treatment capacity of 55 L-water g-adsorbent for feed Pb concentration of 1 mg L, which is 1-3 orders of magnitude higher than other 2D materials and commercial activated carbon.