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 2+ ) (a common HMI) removal capacity (up to 758 mg g −1 ) is achieved using our synthesized metallic 1T/1T′ phase 2D transition metal dichalcogenide (TMD, including MoS 2 , WS 2 , TaS 2 , and TiS 2 ) nanosheets, which hold tremendous activated S chemisorption sites. The residual Pb 2+ concentration can be reduced from 2 mg L −1 to 2 μg L −1 within 0.5 min, meeting the drinking water standards following World Health Organization guideline (Pb 2+ concentrations <10 μg L −1 ). Atomic-scale characterizations and calculations based on density functional theory unveil that Pb 2+ 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 2 nanosheets exhibit treatment capacity of 55 L-water g −1 -adsorbent for feed Pb 2+ concentration of 1 mg L −1 , which is 1-3 orders of magnitude higher than other 2D materials and commercial activated carbon.