fig16

Figure 16. Structures of Mo₂CrC₂ supercell (2 × 2 × 1): (A) top view; (B) side view; (C) considered adsorption sites on the surface of Mo₂CrC₂ monolayer (top view). (D) Schematic diagram of top-view Mo₂CrC₂ with three high-symmetry sites. (C) Adsorption energy of metal ions in the first layer is located at Mo, Cr and C atom sites on both sides for Mo₂CrC₂ monolayer surface. (E) To test the energy stability of metal ions on the monolayer Mo₂CrC₂ MXene, the average calculated adsorption energy of Li⁺, Na⁺, K⁺ and Mg²⁺ in different states has similar adsorption sites. Reproduced with permission from Ref.^[209] (Copyright 2020, Applied Surface Science, Elsevier).