Fig. 5.

DFT calculations of the optimized structure and the corresponding binding energies for Cu²⁺ and Pb²⁺ in the MoS₂-COOH systems. (A–C) Cu²⁺ ion in the bulk solution, bound to monolayer and bilayer MoS₂-COOH, respectively. (D–F) Pb²⁺ ion in the bulk solution, bound to monolayer and bilayer MoS₂-COOH, respectively. BE: binding energy. Mo is represented in yellow, S in gray, C in cyan, O in red, H in white, Cl in green, Cu in orange, and Pb in ice blue.