Fabrication of 1T-MoS2 nanosheets and the high-efficiency removal of toxic metals in aquatic systems: Performance and mechanisms

Synthesized MoS2 nanosheets have disadvantages such as low purity (phase conversion), low stability (charge density), limited active sites and complex preparation procedures, severely hindering their applications, such as in water treatment. Herein, a facile method was designed to synthesize high-phase-purity and high-negativecharge-density solar-induced atomic-defect-rich 1T-MoS2 (S-ADR-MoS2) nanosheets. Sunlight irradiation drove the formation of atomic vacancies (diameters between approximately 0.4 and 0.9 nm; S and Mo were codeleted) in the 1T-MoS2 nanosheets by attacking center dot OH and center dot O2-. Consequently, S-ADR-MoS2 exhibited high selectivity and affinity for toxic metals, and 1 g S-ADR-MoS2 under 1 and 4 sun illuminations captured 638 mg and 902 mg Pb2+, respectively, which is better than the performance of most graphene-based and sulfur-functionalized nanomaterials. We demonstrated that the ionic capture of defect-rich features via strong Lewis soft - soft interactions and electrostatic attractions was the dominant mechanism for the improved Pb2+ removal capacity under sunlight irradiation. Furthermore, the layer-stacked S-ADR-MoS2 membrane achieved high water fluxes (181-345 L m(-2)h(-1) bar(-1)) and a high separation performance for Pb2+ (84.5-99.6%), resulting in a Pb2+ concentration in treated water that was below the U. S. Environmental Protection Agency limits for drinking water. S-ADR-MoS2 was also able to efficiently capture other toxic metals, such as Al3+ and Cd2+, thus exhibiting high potential for the treatment of contaminated drinking water.