Rapid reaction of MoS₂ nanosheets with Pb²⁺ and Pb⁴⁺ ions in solution

Abstract

Understanding the chemical changes happening to nanostructures during a process is vital in selecting them for applications. Here, we investigated the difference in the reactivity of the bulk and nanoscale forms of molybdenum disulfide (MoS) in solution with lead ions (Pb and Pb) as probes, at room temperature. While the bulk form did not show any reactivity in the experimental timescale, the two-dimensional (2D) nanoscale form showed not only reactivity but also quite rapid kinetics that resulted in the formation of distinct products, principally PbMoO with anion substitution, in a few seconds. Depending on the charge state of the cation, and the pH of the reaction mixture, two different kinds of morphologies of the same reaction product were formed. Furthermore, we demonstrate that this unusual reactivity of the MoS nanosheets (NSs) was retained in its supported form and hence, such supported materials can be effective for the abstraction of toxic lead from water, with fast kinetics.

Interaction of Pb2+ ions in water with two-dimensional molybdenum disulfide

“…Based on our XPS results, we do not observe any Pb(0). The reaction here is more similar to the interaction of chemically exfoliated 1T-MoS 2 with higher concentrations of Pb 2+ and Pb 4+ , which led to the formation of PbMoO 4 [21]. These results are all consistent with the water and oxygen induced dissolution of MoS 2 that has previously been reported, with the 1T phase degrading much more quickly than the 2H phase [45].…”

“…The broadness of these peaks is likely due to contributions from multiple compounds and from very small particles. Because the earlier XPS results indicated the presence of only Pb, Mo, O, and S, we have identified possible contributions from PbMoO 4 [21,56] and PbSO 4 [57], whose reference XRD patterns are shown in figure 5. The Pb-containing compounds are consistent with the XPS results described earlier.…”

“…Meanwhile, some recent papers have presented some possible mechanisms of the interaction between MoS 2 chemically exfoliated with n-butyllithium, which forms the metallic 1T-MoS 2 phase and metal ions. These works include a reductive adsorption pathway for Ag + ions to form Ag metal by Wang et al [11], and a reactive pathway between Pb 2+ and Pb 4+ ions to form PbMoO 4 by Mondal et al [21]. In the past couple of years, there have been various methods applied to modified MoS 2 to remove Pb from water including phase engineering [22], defect engineering [23], control of interlaying spacing [24,25], and vertical alignment of nanosheets [26].…”

Ultrathin WO3 Nanosheets Converted from Metallic WS2 Sheets by Spontaneous Formation and Deposition of PdO Nanoclusters for Visible Light-Driven C–C Coupling Reactions

“…As Pd­(OAc) 2 was added in the metallic WS 2 solution instead of K 2 PdCl 4 , the same nanostructure of PdO@WO 3 was obtained. According to previous studies, metallic MoS 2 nanosheets were not converted into MoO 3 when they reacted with other metal ions such as gold, silver, platinum, and lead. − …”

‘Template-free’ hierarchical MoS2foam as a sustainable ‘green’ scavenger of heavy metals and bacteria in point of use water purification

“…35,36 Recently, exfoliated MoS 2 nanosheets have been shown to rapidly interact with the Pb(II) and Pb(IV) species in water and yield a PbMoO 4Àx S x product. 37 This work portrays the potential of using 2D MoS 2 nanosheets in water purication applications. However, in this study, the removal of Pb ions could only be achieved by surface adsorbing these 2D nanosheets on alumina or silica substrates.…”