Theoretical Study of Carbon K‐Edge Energy‐Loss Near‐Edge Structure Spectra in the Ordered Mo₂TiAlC₂ MAX and Mo₂TiC₂ MXene

By means of density functional theory, the energy‐loss near‐edge structure (ELNES) of carbon K‐edge of Mo2TiAlC 2 and corresponding MoTiC 2 Mxene at orientational‐independent condition is dealt with. Compared to the MAX (M is transition metal, A is an elment from group 13–16, X is C or N) phase, the energy separations increase between the main spectral features at the C K edge of Mo 2 TiC 2 MXene owing to the structural change and decreased bond length. The dispersions of the C K edge in both systems are similar to p‐symmetry densities of states. It is indicated that the source of the first fine structure at the C 1 s edge in both phases mainly comes from the electron transfer to p x + p y ‐like character. The other fine structures result from the transition to hybridization of p z and p x + p y states with the prominent contribution of p x + p y ‐like character. Moreover, the comparison of C K‐edge ELNES spectra in three Mo‐based compounds reveals that, ongoing from Mo 2 TiAlC 2 to Mo 2 TiC 2 and then to Mo 2 C, the energy position of the fine structures is shifted to higher energies (blueshifted), due to the quantum confinement effects and the change of the chemical environment around the excited carbon.