MoS2-Nanosheet-Assisted Coordination of Metal Ions with Porphyrin for Rapid Detection and Removal of Cadmium Ions in Aqueous Media.

Molybdenum disulfide (MoS2) is a two-dimensional (2D) graphene-like material that is gaining great attention because of its potential application in various fields. Here, we reported a self-assembled nanocomposite consisted of MoS2 nanosheets and 5,10,15,20-tetrakis(1-methyl-4-pyridinio)porphyrintetra(p-toluenesulfonate) (TMPyP), named MoS2@TMPyP. This nanocomposite can be used as a sensing probe for low cost, rapid, selective detection of cadmium (Cd2+) ions. It is found that a new Soret band at 442 nm in UV-vis absorption spectra represented the coordination of Cd2+ ions into TMPyP of the MoS2@TMPyP. The coordination rates between TMPyP and Cd2+ ions is greatly accelerated from 72 h to 20 min with the assistance of MoS2, which is 200 times faster than in the absence of MoS2. The limit of detection (LOD) of the Cd2+ is as low as 7.2 × 10-8 mol/L. The binding behavior between the cationic TMPyP and MoS2 nanosheets was corroborated by molecular dynamics simulation and various control experiments. The results demonstrated that electrostatic interaction was the main force for driving TMPyP enriching around the MoS2 surface, resulting in an accelerated complexation of Cd2+ and TMPyP. Moreover, MoS2@TMPyP nanocomposite can also be used for removing of Cd2+ in water. The removal efficiency (RF) of the MoS2@TMPyP can reach to 91% for high concentrations of Cd2+. This work provides a new insight into detection and removal of Cd2+ ions in water.