Multi-functional nanohybrid of ultrathin molybdenum disulfide nanosheets decorated with cerium oxide nanoparticles for preferential uptake of lead (II) ions

Molybdenum disulfide-based 2D nanomaterials have become an attractive target for investigations in various fields. However, their potential application in the important area of environmental science has not yet been effectively explored. In this work, ultrathin molybdenum disulfide nanosheets decorated with cerium oxide nanoparticles (MoS 2 /CeO 2 ) nanohybrids were synthesized using a two-step hydrothermal reaction and used to remove Pb 2+ as a representative heavy metal ion. A detailed characterization, including transmission electron microscopy (TEM), Fourier transform infrared (FT-IR) spectrum, X-ray photoelectron spectroscopy (XPS), and thermogravimetric analysis (TGA), confirmed the formation of the MoS 2 /CeO 2 nanohybrids. Furthermore, different factors affecting the sorption process, such as pH, adsorbent amount, contact time, ion strength, and reusability, were studied in detail. The adsorption kinetic data were described well with the pseudo-second-order model, and the equilibrium data were fitted well to Langmuir isotherms. The as-prepared nanohybrids exhibited a high uptake ability (333 mg g −1 at pH 2.0) and excellent reusability. More importantly, hybrid materials showed preferential Pb 2+ uptake behaviour compared to other heavy metal ions such as Cd 2+ (3.24 mg g −1 ), Cu 2+ (5.3 mg g −1 ), Zn 2+ (3 mg g −1 ), Co 2+ (1.8 mg g −1 ), Ni 2+ (1.3 mg g −1 ), Mn 2+ (2.1 mg g −1 ), and Cr 3+ (1.76 mg g −1 ). The adsorption mechanism may be attributed to the intrinsically sulfur-rich characteristic, the strong soft-soft interactions between S atoms and Pb atoms, the interlayer spacing capture, and weak ion-exchange interaction. These findings open the possibility of expanding the applications of transition metal dichalcogenide-based materials in the environmental sciences.